rfc9915.original   rfc9915.txt 
Network Working Group T. Mrugalski Internet Engineering Task Force (IETF) T. Mrugalski
Internet-Draft ISC Request for Comments: 9915 ISC
Obsoletes: 8415 (if approved) B. Volz Obsoletes: 8415 B. Volz
Intended status: Standards Track Individual Contributor Category: Standards Track Individual Contributor
Expires: 6 December 2025 M. Richardson ISSN: 2070-1721 M. Richardson
SSW SSW
S. Jiang S. Jiang
BUPT BUPT
T. Winters T. Winters
QA Cafe QA Cafe
4 June 2025 November 2025
Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Dynamic Host Configuration Protocol for IPv6 (DHCPv6)
draft-ietf-dhc-rfc8415bis-12
Abstract Abstract
This document specifies the Dynamic Host Configuration Protocol for This document specifies the Dynamic Host Configuration Protocol for
IPv6 (DHCPv6): an extensible mechanism for configuring nodes with IPv6 (DHCPv6), an extensible mechanism for configuring nodes with
network configuration parameters, IP addresses, and prefixes. network configuration parameters, IP addresses, and prefixes.
Parameters can be provided statelessly, or in combination with Parameters can be provided statelessly or in combination with
stateful assignment of one or more IPv6 addresses and/or IPv6 stateful assignment of one or more IPv6 addresses and/or IPv6
prefixes. DHCPv6 can operate either in place of or in addition to prefixes. DHCPv6 can operate either in place of or in addition to
stateless address autoconfiguration (SLAAC). stateless address autoconfiguration (SLAAC).
This document obsoletes RFC8415 to incorporate reported errata and to This document obsoletes RFC 8415 to incorporate reported errata and
obsolete the assignment of temporary addresses (the IA_TA option) and to obsolete the assignment of temporary addresses (the IA_TA option)
the server unicast capability (the Server Unicast option and and the server unicast capability (the Server Unicast option and
UseMulticast status code). UseMulticast status code).
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Internet Standards is available in Section 2 of RFC 7841.
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and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9915.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction
1.1. Relationship to Previous DHCPv6 Standards . . . . . . . . 6 1.1. Relationship to Previous DHCPv6 Standards
1.2. Topics Out of Scope . . . . . . . . . . . . . . . . . . . 7 1.2. Topics Out of Scope
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 7 2. Requirements
3. Background . . . . . . . . . . . . . . . . . . . . . . . . . 7 3. Background
4. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 8 4. Terminology
4.1. IPv6 Terminology . . . . . . . . . . . . . . . . . . . . 8 4.1. IPv6 Terminology
4.2. DHCP Terminology . . . . . . . . . . . . . . . . . . . . 9 4.2. DHCP Terminology
5. Client/Server Exchanges . . . . . . . . . . . . . . . . . . . 13 5. Client/Server Exchanges
5.1. Client/Server Exchanges Involving Two Messages . . . . . 14 5.1. Client/Server Exchanges Involving Two Messages
5.2. Client/Server Exchanges Involving Four Messages . . . . . 15 5.2. Client/Server Exchanges Involving Four Messages
5.3. Server/Client Exchanges . . . . . . . . . . . . . . . . . 15 5.3. Server/Client Exchanges
6. Operational Models . . . . . . . . . . . . . . . . . . . . . 15 6. Operational Models
6.1. Stateless DHCP . . . . . . . . . . . . . . . . . . . . . 16 6.1. Stateless DHCP
6.2. DHCP for Non-temporary Address Assignment . . . . . . . . 16 6.2. DHCP for Non-Temporary Address Assignment
6.3. DHCP for Prefix Delegation . . . . . . . . . . . . . . . 17 6.3. DHCP for Prefix Delegation
6.4. DHCP for Customer Edge Routers . . . . . . . . . . . . . 20 6.4. DHCP for Customer Edge Routers
6.5. Multiple Addresses and Prefixes . . . . . . . . . . . . . 20 6.5. Multiple Addresses and Prefixes
6.6. Registering Self-generated Addresses . . . . . . . . . . 21 6.6. Registering Self-Generated Addresses
7. DHCP Constants . . . . . . . . . . . . . . . . . . . . . . . 21 7. DHCP Constants
7.1. Multicast Addresses . . . . . . . . . . . . . . . . . . . 21 7.1. Multicast Addresses
7.2. UDP Ports . . . . . . . . . . . . . . . . . . . . . . . . 21 7.2. UDP Ports
7.3. DHCP Message Types . . . . . . . . . . . . . . . . . . . 22 7.3. DHCP Message Types
7.4. DHCP Option Codes . . . . . . . . . . . . . . . . . . . . 24 7.4. DHCP Option Codes
7.5. Status Codes . . . . . . . . . . . . . . . . . . . . . . 24 7.5. Status Codes
7.6. Transmission and Retransmission Parameters . . . . . . . 24 7.6. Transmission and Retransmission Parameters
7.7. Representation of Time Values and "Infinity" as a Time 7.7. Representation of Time Values and "Infinity" as a Time
Value . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Value
8. Client/Server Message Formats . . . . . . . . . . . . . . . . 26 8. Client/Server Message Formats
9. Relay Agent/Server Message Formats . . . . . . . . . . . . . 27 9. Relay Agent/Server Message Formats
9.1. Relay-forward Message . . . . . . . . . . . . . . . . . . 28 9.1. Relay-forward Message
9.2. Relay-reply Message . . . . . . . . . . . . . . . . . . . 29 9.2. Relay-reply Message
10. Representation and Use of Domain Names . . . . . . . . . . . 29 10. Representation and Use of Domain Names
11. DHCP Unique Identifier (DUID) . . . . . . . . . . . . . . . . 29 11. DHCP Unique Identifier (DUID)
11.1. DUID Contents . . . . . . . . . . . . . . . . . . . . . 30 11.1. DUID Contents
11.2. DUID Based on Link-Layer Address Plus Time (DUID-LLT) . 31 11.2. DUID Based on Link-Layer Address Plus Time (DUID-LLT)
11.3. DUID Assigned by Vendor Based on Enterprise Number 11.3. DUID Assigned by Vendor Based on Enterprise Number
(DUID-EN) . . . . . . . . . . . . . . . . . . . . . . . 32 (DUID-EN)
11.4. DUID Based on Link-Layer Address (DUID-LL) . . . . . . . 33 11.4. DUID Based on Link-Layer Address (DUID-LL)
11.5. DUID Based on Universally Unique Identifier 11.5. DUID Based on Universally Unique Identifier (DUID-UUID)
(DUID-UUID) . . . . . . . . . . . . . . . . . . . . . . 34 12. Identity Association
12. Identity Association . . . . . . . . . . . . . . . . . . . . 35 12.1. Identity Associations for Address Assignment
12.1. Identity Associations for Address Assignment . . . . . . 35 12.2. Identity Associations for Prefix Delegation
12.2. Identity Associations for Prefix Delegation . . . . . . 36 13. Assignment to an IA
13. Assignment to an IA . . . . . . . . . . . . . . . . . . . . . 36 13.1. Selecting Addresses for Assignment to an IA_NA
13.1. Selecting Addresses for Assignment to an IA_NA . . . . . 36 13.2. Assignment of Prefixes for IA_PD
13.2. Assignment of Prefixes for IA_PD . . . . . . . . . . . . 37 14. Transmission of Messages by a Client
14. Transmission of Messages by a Client . . . . . . . . . . . . 37 14.1. Rate Limiting
14.1. Rate Limiting . . . . . . . . . . . . . . . . . . . . . 38 14.2. Client Behavior when T1 and/or T2 Are 0
14.2. Client Behavior when T1 and/or T2 Are 0 . . . . . . . . 38 15. Reliability of Client-Initiated Message Exchanges
15. Reliability of Client-Initiated Message Exchanges . . . . . . 39 16. Message Validation
16. Message Validation . . . . . . . . . . . . . . . . . . . . . 41 16.1. Use of Transaction IDs
16.1. Use of Transaction IDs . . . . . . . . . . . . . . . . . 42 16.2. Solicit Message
16.2. Solicit Message . . . . . . . . . . . . . . . . . . . . 42 16.3. Advertise Message
16.3. Advertise Message . . . . . . . . . . . . . . . . . . . 42 16.4. Request Message
16.4. Request Message . . . . . . . . . . . . . . . . . . . . 43 16.5. Confirm Message
16.5. Confirm Message . . . . . . . . . . . . . . . . . . . . 43 16.6. Renew Message
16.6. Renew Message . . . . . . . . . . . . . . . . . . . . . 43 16.7. Rebind Message
16.7. Rebind Message . . . . . . . . . . . . . . . . . . . . . 43 16.8. Decline Message
16.8. Decline Message . . . . . . . . . . . . . . . . . . . . 44 16.9. Release Message
16.9. Release Message . . . . . . . . . . . . . . . . . . . . 44 16.10. Reply Message
16.10. Reply Message . . . . . . . . . . . . . . . . . . . . . 44 16.11. Reconfigure Message
16.11. Reconfigure Message . . . . . . . . . . . . . . . . . . 45 16.12. Information-request Message
16.12. Information-request Message . . . . . . . . . . . . . . 45 16.13. Relay-forward Message
16.13. Relay-forward Message . . . . . . . . . . . . . . . . . 46 16.14. Relay-reply Message
16.14. Relay-reply Message . . . . . . . . . . . . . . . . . . 46 17. Client Source Address and Interface Selection
17. Client Source Address and Interface Selection . . . . . . . . 46
17.1. Source Address and Interface Selection for Address 17.1. Source Address and Interface Selection for Address
Assignment . . . . . . . . . . . . . . . . . . . . . . . 46 Assignment
17.2. Source Address and Interface Selection for Prefix 17.2. Source Address and Interface Selection for Prefix
Delegation . . . . . . . . . . . . . . . . . . . . . . . 46 Delegation
18. DHCP Configuration Exchanges . . . . . . . . . . . . . . . . 46 18. DHCP Configuration Exchanges
18.1. A Single Exchange for Multiple IA Options . . . . . . . 49 18.1. A Single Exchange for Multiple IA Options
18.2. Client Behavior . . . . . . . . . . . . . . . . . . . . 50 18.2. Client Behavior
18.2.1. Creation and Transmission of Solicit Messages . . . 50 18.2.1. Creation and Transmission of Solicit Messages
18.2.2. Creation and Transmission of Request Messages . . . 53 18.2.2. Creation and Transmission of Request Messages
18.2.3. Creation and Transmission of Confirm Messages . . . 54 18.2.3. Creation and Transmission of Confirm Messages
18.2.4. Creation and Transmission of Renew Messages . . . . 55 18.2.4. Creation and Transmission of Renew Messages
18.2.5. Creation and Transmission of Rebind Messages . . . . 57 18.2.5. Creation and Transmission of Rebind Messages
18.2.6. Creation and Transmission of Information-request 18.2.6. Creation and Transmission of Information-request
Messages . . . . . . . . . . . . . . . . . . . . . . 58 Messages
18.2.7. Creation and Transmission of Release Messages . . . 59 18.2.7. Creation and Transmission of Release Messages
18.2.8. Creation and Transmission of Decline Messages . . . 60 18.2.8. Creation and Transmission of Decline Messages
18.2.9. Receipt of Advertise Messages . . . . . . . . . . . 62 18.2.9. Receipt of Advertise Messages
18.2.10. Receipt of Reply Messages . . . . . . . . . . . . . 63 18.2.10. Receipt of Reply Messages
18.2.10.1. Reply for Solicit (with Rapid Commit), Request, 18.2.10.1. Reply for Solicit (with Rapid Commit), Request,
Renew, or Rebind . . . . . . . . . . . . . . . . . 64 Renew, or Rebind
18.2.10.2. Reply for Release and Decline . . . . . . . . . 66 18.2.10.2. Reply for Release and Decline
18.2.10.3. Reply for Confirm . . . . . . . . . . . . . . . 66 18.2.10.3. Reply for Confirm
18.2.10.4. Reply for Information-request . . . . . . . . . 66 18.2.10.4. Reply for Information-request
18.2.10.5. Revoking Previously Provided Options . . . . . 67 18.2.10.5. Revoking Previously Provided Options
18.2.11. Receipt of Reconfigure Messages . . . . . . . . . . 67 18.2.11. Receipt of Reconfigure Messages
18.2.12. Refreshing Configuration Information . . . . . . . . 68 18.2.12. Refreshing Configuration Information
18.2.13. Restarting Server Discovery Process . . . . . . . . 70 18.2.13. Restarting Server Discovery Process
18.3. Server Behavior . . . . . . . . . . . . . . . . . . . . 70 18.3. Server Behavior
18.3.1. Receipt of Solicit Messages . . . . . . . . . . . . 71 18.3.1. Receipt of Solicit Messages
18.3.2. Receipt of Request Messages . . . . . . . . . . . . 72 18.3.2. Receipt of Request Messages
18.3.3. Receipt of Confirm Messages . . . . . . . . . . . . 74 18.3.3. Receipt of Confirm Messages
18.3.4. Receipt of Renew Messages . . . . . . . . . . . . . 75 18.3.4. Receipt of Renew Messages
18.3.5. Receipt of Rebind Messages . . . . . . . . . . . . . 76 18.3.5. Receipt of Rebind Messages
18.3.6. Receipt of Information-request Messages . . . . . . 78 18.3.6. Receipt of Information-request Messages
18.3.7. Receipt of Release Messages . . . . . . . . . . . . 79 18.3.7. Receipt of Release Messages
18.3.8. Receipt of Decline Messages . . . . . . . . . . . . 80 18.3.8. Receipt of Decline Messages
18.3.9. Creation of Advertise Messages . . . . . . . . . . . 80 18.3.9. Creation of Advertise Messages
18.3.10. Transmission of Advertise and Reply Messages . . . . 82 18.3.10. Transmission of Advertise and Reply Messages
18.3.11. Creation and Transmission of Reconfigure Messages . 82 18.3.11. Creation and Transmission of Reconfigure Messages
19. Relay Agent Behavior . . . . . . . . . . . . . . . . . . . . 83 19. Relay Agent Behavior
19.1. Relaying a Client Message or a Relay-forward Message . . 84 19.1. Relaying a Client Message or a Relay-forward Message
19.1.1. Relaying a Message from a Client . . . . . . . . . . 84 19.1.1. Relaying a Message from a Client
19.1.2. Relaying a Message from a Relay Agent . . . . . . . 85 19.1.2. Relaying a Message from a Relay Agent
19.1.3. Relay Agent Behavior with Prefix Delegation . . . . 85 19.1.3. Relay Agent Behavior with Prefix Delegation
19.2. Relaying a Relay-reply Message . . . . . . . . . . . . . 85 19.2. Relaying a Relay-reply Message
19.3. Construction of Relay-reply Messages . . . . . . . . . . 86 19.3. Construction of Relay-reply Messages
19.4. Interaction between Relay Agents and Servers . . . . . . 87 19.4. Interaction Between Relay Agents and Servers
20. Authentication of DHCP Messages . . . . . . . . . . . . . . . 88 20. Authentication of DHCP Messages
20.1. Security of Messages Sent between Servers and Relay 20.1. Security of Messages Sent Between Servers and Relay Agents
Agents . . . . . . . . . . . . . . . . . . . . . . . . . 88 20.2. Summary of DHCP Authentication
20.2. Summary of DHCP Authentication . . . . . . . . . . . . . 88 20.3. Replay Detection
20.3. Replay Detection . . . . . . . . . . . . . . . . . . . . 89 20.4. Reconfiguration Key Authentication Protocol (RKAP)
20.4. Reconfiguration Key Authentication Protocol (RKAP) . . . 89 20.4.1. Use of the Authentication Option in RKAP
20.4.1. Use of the Authentication Option in RKAP . . . . . . 90 20.4.2. Server Considerations for RKAP
20.4.2. Server Considerations for RKAP . . . . . . . . . . . 91 20.4.3. Client Considerations for RKAP
20.4.3. Client Considerations for RKAP . . . . . . . . . . . 91 21. DHCP Options
21. DHCP Options . . . . . . . . . . . . . . . . . . . . . . . . 91 21.1. Format of DHCP Options
21.1. Format of DHCP Options . . . . . . . . . . . . . . . . . 92 21.2. Client Identifier Option
21.2. Client Identifier Option . . . . . . . . . . . . . . . . 93 21.3. Server Identifier Option
21.3. Server Identifier Option . . . . . . . . . . . . . . . . 93 21.4. Identity Association for Non-Temporary Addresses Option
21.4. Identity Association for Non-temporary Addresses 21.5. Identity Association for Temporary Addresses Option
Option . . . . . . . . . . . . . . . . . . . . . . . . 94 21.6. IA Address Option
21.5. Identity Association for Temporary Addresses Option . . 96 21.7. Option Request Option
21.6. IA Address Option . . . . . . . . . . . . . . . . . . . 96 21.8. Preference Option
21.7. Option Request Option . . . . . . . . . . . . . . . . . 98 21.9. Elapsed Time Option
21.8. Preference Option . . . . . . . . . . . . . . . . . . . 100 21.10. Relay Message Option
21.9. Elapsed Time Option . . . . . . . . . . . . . . . . . . 100 21.11. Authentication Option
21.10. Relay Message Option . . . . . . . . . . . . . . . . . . 101 21.12. Server Unicast Option
21.11. Authentication Option . . . . . . . . . . . . . . . . . 102 21.13. Status Code Option
21.12. Server Unicast Option . . . . . . . . . . . . . . . . . 103 21.14. Rapid Commit Option
21.13. Status Code Option . . . . . . . . . . . . . . . . . . . 104 21.15. User Class Option
21.14. Rapid Commit Option . . . . . . . . . . . . . . . . . . 105 21.16. Vendor Class Option
21.15. User Class Option . . . . . . . . . . . . . . . . . . . 106 21.17. Vendor-Specific Information Option
21.16. Vendor Class Option . . . . . . . . . . . . . . . . . . 108 21.18. Interface-Id Option
21.17. Vendor-specific Information Option . . . . . . . . . . . 109 21.19. Reconfigure Message Option
21.18. Interface-Id Option . . . . . . . . . . . . . . . . . . 111 21.20. Reconfigure Accept Option
21.19. Reconfigure Message Option . . . . . . . . . . . . . . . 112 21.21. Identity Association for Prefix Delegation Option
21.20. Reconfigure Accept Option . . . . . . . . . . . . . . . 113 21.22. IA Prefix Option
21.21. Identity Association for Prefix Delegation Option . . . 113 21.23. Information Refresh Time Option
21.22. IA Prefix Option . . . . . . . . . . . . . . . . . . . . 115 21.24. SOL_MAX_RT Option
21.23. Information Refresh Time Option . . . . . . . . . . . . 117 21.25. INF_MAX_RT Option
21.24. SOL_MAX_RT Option . . . . . . . . . . . . . . . . . . . 119 22. Security Considerations
21.25. INF_MAX_RT Option . . . . . . . . . . . . . . . . . . . 120 22.1. Client Security Considerations
22. Implementation status . . . . . . . . . . . . . . . . . . . . 121 22.2. Server Security Considerations
23. Security Considerations . . . . . . . . . . . . . . . . . . . 125 22.3. Reconfigure Security Considerations
23.1. Client Security Considerations . . . . . . . . . . . . . 125 22.4. Mitigation Considerations
23.2. Server Security Considerations . . . . . . . . . . . . . 126 23. Privacy Considerations
23.3. Reconfigure Security Considerations . . . . . . . . . . 126 24. IANA Considerations
23.4. Mitigation Considerations . . . . . . . . . . . . . . . 127 25. References
24. Privacy Considerations . . . . . . . . . . . . . . . . . . . 128 25.1. Normative References
25. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 128 25.2. Informative References
26. References . . . . . . . . . . . . . . . . . . . . . . . . . 129 Appendix A. Summary of Changes from RFC 8415
26.1. Normative References . . . . . . . . . . . . . . . . . . 129 Appendix B. Appearance of Options in Message Types
26.2. Informative References . . . . . . . . . . . . . . . . . 131
Appendix A. Summary of Changes . . . . . . . . . . . . . . . . . 136
Appendix B. Appearance of Options in Message Types . . . . . . . 137
Appendix C. Appearance of Options in the "options" Field of DHCP Appendix C. Appearance of Options in the "options" Field of DHCP
Options . . . . . . . . . . . . . . . . . . . . . . . . . 138 Options
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 139 Acknowledgments
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 140 Authors' Addresses
1. Introduction 1. Introduction
This document specifies DHCP for IPv6 (DHCPv6), a client/server This document specifies DHCP for IPv6 (DHCPv6), a client/server
protocol that provides managed configuration of devices. The basic protocol that provides managed configuration of devices. The basic
operation of DHCPv6 provides configuration for clients connected to operation of DHCPv6 provides configuration for clients connected to
the same link as the server. Relay agent functionality is also the same link as the server. Relay agent functionality is also
defined for enabling communication between clients and servers that defined for enabling communication between clients and servers that
are not on the same link. are not on the same link.
skipping to change at page 6, line 40 skipping to change at line 269
DHCP can also be used just to provide other configuration options DHCP can also be used just to provide other configuration options
(i.e., no addresses or prefixes). That implies that the server does (i.e., no addresses or prefixes). That implies that the server does
not have to track any state; thus, this mode is called "stateless not have to track any state; thus, this mode is called "stateless
DHCPv6". Mechanisms necessary to support stateless DHCPv6 are much DHCPv6". Mechanisms necessary to support stateless DHCPv6 are much
simpler than mechanisms needed to support stateful DHCPv6. simpler than mechanisms needed to support stateful DHCPv6.
1.1. Relationship to Previous DHCPv6 Standards 1.1. Relationship to Previous DHCPv6 Standards
[RFC8415] provided a unified, corrected, and cleaned-up definition of [RFC8415] provided a unified, corrected, and cleaned-up definition of
DHCPv6 that also covered all applicable errata filed against older DHCPv6 that also covered all applicable errata filed against older
RFCs. It also obsoleted a small number of mechanisms: delayed RFCs at the time of its writing. It also obsoleted a small number of
authentication, lifetime and timer hints sent by a client. mechanisms: delayed authentication, lifetime and timer hints sent by
a client.
This document obsoletes [RFC8415] by applying all applicable errata This document obsoletes [RFC8415] by applying all applicable errata
and obsoleting two features that have not been widely implemented - and obsoleting two features that have not been widely implemented:
the assignment of temporary addresses using the IA_TA option and the assignment of temporary addresses using the IA_TA option and
allowing clients to unicast some messages directly to the server if allowing clients to unicast some messages directly to the server if
the server sent the Server Unicast option to a client in an early the server sent the Server Unicast option to a client in an early
exchange. It also clarifies the UDP ports used by clients, servers, exchange. It also clarifies the UDP ports used by clients, servers,
and relay agents (Section 7.2). See Appendix A for a list of and relay agents (Section 7.2). See Appendix A for a list of
differences from [RFC8415]. differences from [RFC8415].
1.2. Topics Out of Scope 1.2. Topics Out of Scope
This document specifies the DHCPv6 protocol behavior. The server This document specifies DHCPv6 behavior. The server policy, such as
policy, such as what options to assign to which clients, which what options to assign to which clients, which subnets or pools of
subnets or pools of resources to use, which clients' requests should resources to use, which clients' requests should be denied, etc. are
be denied etc. are out of scope for this document. out of scope for this document.
Server configuration, operation and management are also out of scope. Server configuration, operation, and management are also out of
An approach to manage DHCPv6 relays and servers is specified in scope. An approach to manage DHCPv6 relays and servers is specified
[RFC9243]. in [RFC9243].
Merging DHCPv4 [RFC2131] and DHCPv6 configuration is out of scope for Merging DHCPv4 [RFC2131] and DHCPv6 configuration is out of scope for
this document. [RFC4477] discusses some issues and possible this document. [RFC4477] discusses some issues and possible
strategies for running DHCPv4 and DHCPv6 services together. While strategies for running DHCPv4 and DHCPv6 services together. While
[RFC4477] is a bit dated, it provides a good overview of the issues [RFC4477] is a bit dated, it provides a good overview of the issues
at hand. The current consensus of the IETF is that DHCPv4 should be at hand. The consensus of the IETF at the time of writing is that
used rather than DHCPv6 when conveying IPv4 configuration information DHCPv4 should be used rather than DHCPv6 when conveying IPv4
to nodes. For IPv6-only networks, [RFC7341] describes a transport configuration information to nodes. For IPv6-only networks,
mechanism to carry DHCPv4 messages using the DHCPv6 protocol for the [RFC7341] describes a transport mechanism to carry DHCPv4 messages
dynamic provisioning of IPv4 address and configuration information. using DHCPv6 for the dynamic provisioning of IPv4 address and
configuration information.
2. Requirements 2. Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in BCP
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
This document also makes use of internal conceptual variables to This document also makes use of internal conceptual variables to
describe protocol behavior and external variables that an describe protocol behavior and external variables that an
implementation must allow system administrators to change. The implementation must allow system administrators to change. The
specific variable names, how their values change, and how their specific variable names, how their values change, and how their
settings influence protocol behavior are provided to demonstrate settings influence protocol behavior are provided to demonstrate
protocol behavior. An implementation is not required to have them in protocol behavior. An implementation is not required to have them in
the exact form described here, as long as its external behavior is the exact form described here, as long as its external behavior is
consistent with that described in this document. consistent with that described in this document.
3. Background 3. Background
This section, which contained background on IPv6 specifications of In [RFC8415], the "Background" section contained background on IPv6
relevance to DHCPv6, has been removed; those interested should refer specifications of relevance to DHCPv6. That text has been removed
to [RFC8415]. However, this section is retained to keep the major from the current document; however, this section has been retained to
section numbering consistent with [RFC8415]. keep the major section numbering consistent with [RFC8415]. Those
interested can refer to [RFC8415] itself for more information on the
topic.
4. Terminology 4. Terminology
This section defines terminology specific to IPv6 and DHCP used in This section defines terminology specific to IPv6 and DHCP used in
this document. this document.
4.1. IPv6 Terminology 4.1. IPv6 Terminology
IPv6 terminology from [RFC8200], [RFC4291], and [RFC4862] relevant to IPv6 terminology from [RFC8200], [RFC4291], and [RFC4862] relevant to
this specification is included below. this specification is included below.
address An IP-layer identifier for an interface or address
a set of interfaces. An IP-layer identifier for an interface or a set of interfaces.
GUA Global unicast address (see [RFC4291]). GUA
Global unicast address (see [RFC4291]).
host Any node that is not a router. host
Any node that is not a router.
IP Internet Protocol Version 6 (IPv6). The IP
terms "IPv4" and "IPv6" are used only in Internet Protocol Version 6 (IPv6). The terms "IPv4" and "IPv6"
contexts where it is necessary to avoid are used only in contexts where it is necessary to avoid
ambiguity. ambiguity.
interface A node's attachment to a link. interface
A node's attachment to a link.
link A communication facility or medium over link
which nodes can communicate at the link A communication facility or medium over which nodes can
layer, i.e., the layer immediately below communicate at the link layer, i.e., the layer immediately below
IP. Examples are Ethernet (simple or IP. Examples are Ethernet (simple or bridged); Point-to-Point
bridged); Point-to-Point Protocol (PPP) and Protocol (PPP) and PPP over Ethernet (PPPoE) links; and Internet-
PPP over Ethernet (PPPoE) links; and layer (or higher) "tunnels", such as tunnels over IPv4 or IPv6
Internet-layer (or higher) "tunnels", such itself.
as tunnels over IPv4 or IPv6 itself.
link-layer identifier A link-layer identifier for an interface -- link-layer identifier
for example, IEEE 802 addresses for A link-layer identifier for an interface -- for example, IEEE 802
Ethernet or Token Ring network interfaces. addresses for Ethernet or Token Ring network interfaces.
link-local address An IPv6 address having a link-only scope, link-local address
indicated by having the prefix (fe80::/10), An IPv6 address having a link-only scope, indicated by having the
that can be used to reach neighboring nodes prefix (fe80::/10), that can be used to reach neighboring nodes
attached to the same link. Every IPv6 attached to the same link. Every IPv6 interface on which DHCPv6
interface on which DHCPv6 can reasonably be can reasonably be useful has a link-local address.
useful has a link-local address.
multicast address An identifier for a set of interfaces multicast address
(typically belonging to different nodes). An identifier for a set of interfaces (typically belonging to
A packet sent to a multicast address is different nodes). A packet sent to a multicast address is
delivered to all interfaces identified by delivered to all interfaces identified by that address.
that address.
neighbor A node attached to the same link. neighbor
A node attached to the same link.
node A device that implements IP. node
A device that implements IP.
packet An IP header plus payload. packet
An IP header plus payload.
prefix The initial bits of an address, or a set prefix
of IP addresses that share the same The initial bits of an address, or a set of IP addresses that
initial bits. share the same initial bits.
prefix length The number of bits in a prefix. prefix length
The number of bits in a prefix.
router A node that forwards IP packets not router
explicitly addressed to itself. A node that forwards IP packets not explicitly addressed to
itself.
ULA Unique local address (see [RFC4193]). ULA
Unique local address (see [RFC4193]).
unicast address An identifier for a single interface. A unicast address
packet sent to a unicast address is An identifier for a single interface. A packet sent to a unicast
delivered to the interface identified by address is delivered to the interface identified by that address.
that address.
4.2. DHCP Terminology 4.2. DHCP Terminology
Terminology specific to DHCP can be found below. Terminology specific to DHCP can be found below.
appropriate to the link An address is "appropriate to the link" appropriate to the link
when the address is consistent with the An address is "appropriate to the link" when the address is
DHCP server's knowledge of the network consistent with the DHCP server's knowledge of the network
topology, prefix assignment, and address topology, prefix assignment, and address assignment policies.
assignment policies.
binding A binding (or client binding) is a group of
server data records containing the
information the server has about the
addresses or delegated prefixes in an
Identity Association (IA) or configuration
information explicitly assigned to the
client. Configuration information that has
been returned to a client through a policy,
such as the information returned to all
clients on the same link, does not require
a binding. A binding containing
information about an IA is indexed by the
tuple <DUID, IA-type, IAID> (where IA-type
is the type of lease in the IA -- for
example, address or delegated prefix). A
binding containing configuration
information for a client is indexed by
<DUID>. See below for definitions of DUID,
IA, and IAID.
configuration parameter An element of the configuration information binding
set on the server and delivered to the A binding (or client binding) is a group of server data records
client using DHCP. Such parameters may be containing the information the server has about the addresses or
used to carry information to be used by a delegated prefixes in an Identity Association (IA) or
node to configure its network subsystem and configuration information explicitly assigned to the client.
enable communication on a link or Configuration information that has been returned to a client
internetwork, for example. through a policy, such as the information returned to all clients
on the same link, does not require a binding. A binding
containing information about an IA is indexed by the tuple <DUID,
IA-type, IAID> (where IA-type is the type of lease in the IA --
for example, address or delegated prefix). A binding containing
configuration information for a client is indexed by <DUID>. See
below for definitions of DUID, IA, and IAID.
container option An option that encapsulates other options configuration parameter
(for example, the IA_NA option (see An element of the configuration information set on the server and
Section 21.4) may contain IA Address delivered to the client using DHCP. Such parameters may be used
options (see Section 21.6)). to carry information to be used by a node to configure its network
subsystem and enable communication on a link or internetwork, for
example.
DHCP Dynamic Host Configuration Protocol for container option
IPv6. The terms "DHCPv4" and "DHCPv6" are An option that encapsulates other options (for example, the IA_NA
used only in contexts where it is necessary option (see Section 21.4) may contain IA Address options (see
to avoid ambiguity. Section 21.6)).
DHCP client Also referred to as "client". A node that DHCP
initiates requests on a link to obtain Dynamic Host Configuration Protocol for IPv6. The terms "DHCPv4"
configuration parameters from one or more and "DHCPv6" are used only in contexts where it is necessary to
DHCP servers. avoid ambiguity.
DHCP domain A set of links managed by DHCP and operated DHCP client
by a single administrative entity. Also referred to as "client". A node that initiates requests on a
link to obtain configuration parameters from one or more DHCP
servers.
DHCP relay agent Also referred to as "relay agent". A node DHCP domain
that acts as an intermediary to deliver A set of links managed by DHCP and operated by a single
DHCP messages between clients and servers. administrative entity.
In certain configurations, there may be
more than one relay agent between clients
and servers, so a relay agent may send DHCP
messages to another relay agent.
DHCP server This document condenses this term to DHCP relay agent
"server". A node that responds to requests Also referred to as "relay agent". A node that acts as an
from clients. It may or may not be on the intermediary to deliver DHCP messages between clients and servers.
same link as the client(s). In certain configurations, there may be more than one relay agent
between clients and servers, so a relay agent may send DHCP
messages to another relay agent.
DUID A DHCP Unique Identifier for a DHCP DHCP server
participant. Each DHCP client and server This document condenses this term to "server". A node that
has exactly one DUID. See Section 11 for responds to requests from clients. It may or may not be on the
details of the ways in which a DUID may be same link as the client(s).
constructed.
encapsulated option A DHCP option that is usually only DUID
contained in another option. For example, A DHCP Unique Identifier for a DHCP participant. Each DHCP client
the IA Address option is contained in IA_NA and server has exactly one DUID. See Section 11 for details of
options (see Section 21.5). See Section 9 the ways in which a DUID may be constructed.
of [RFC7227] for a more complete
definition.
IA Identity Association: a collection of encapsulated option
leases assigned to a client. Each IA has A DHCP option that is usually only contained in another option.
an associated IAID (see below). A client For example, the IA Address option is contained in IA_NA options
may have more than one IA assigned to it -- (see Section 21.5). See Section 9 of [RFC7227] for a more
for example, one for each of its complete definition.
interfaces. Each IA holds one type of
lease; for example, an identity association
for non-temporary addresses (IA_NA) holds
addresses, and an identity association for
prefix delegation (IA_PD) holds delegated
prefixes. Throughout this document, "IA"
is used to refer to an identity association
without identifying the type of a lease in
the IA. This document defines three IA
types: IA_NA, IA_TA (obsoleted), and IA_PD.
Another IA type (IA_LL) was defined in
[RFC8947] and more may be defined.
IA option(s) In this document, one or more IA_NA, IA_TA IA
(obsoleted), and/or IA_PD. Another IA type Identity Association: a collection of leases assigned to a client.
(IA_LL) was defined in [RFC8947] and more Each IA has an associated IAID (see below). A client may have
may be defined. more than one IA assigned to it -- for example, one for each of
its interfaces. Each IA holds one type of lease; for example, an
identity association for non-temporary addresses (IA_NA) holds
addresses, and an identity association for prefix delegation
(IA_PD) holds delegated prefixes. Throughout this document, "IA"
is used to refer to an identity association without identifying
the type of a lease in the IA. This document defines three IA
types: IA_NA, IA_TA (obsoleted), and IA_PD. Another IA type
(IA_LL) was defined in [RFC8947] and more may be defined.
IAID Identity Association Identifier: an IA option(s)
identifier for an IA, chosen by the client. In this document, one or more IA_NA, IA_TA (obsoleted), and/or
Each IA has an IAID, which is chosen to be IA_PD. Another IA type (IA_LL) was defined in [RFC8947] and more
unique among IAIDs for IAs of a specific may be defined.
type that belong to that client.
IA_NA Identity Association for Non-temporary IAID
Addresses: an IA that carries assigned Identity Association Identifier: an identifier for an IA, chosen
addresses. See Section 21.4 for details on by the client. Each IA has an IAID, which is chosen to be unique
the IA_NA option. among IAIDs for IAs of a specific type that belong to that client.
IA_PD Identity Association for Prefix Delegation: IA_NA
Identity Association for Non-temporary Addresses: an IA that
carries assigned addresses. See Section 21.4 for details on the
IA_NA option.
an IA that carries delegated prefixes. See IA_PD
Section 21.21 for details on the IA_PD Identity Association for Prefix Delegation: an IA that carries
option. delegated prefixes. See Section 21.21 for details on the IA_PD
option.
IA_TA Identity Association for Temporary IA_TA
Addresses: an IA that carries temporary Identity Association for Temporary Addresses: an IA that carries
addresses (see [RFC8981]). This option is temporary addresses (see [RFC8981]). This option is obsoleted by
obsoleted by this document. See [RFC8415] this document. See [RFC8415] for details.
for details.
lease A contract by which the server grants the lease
use of an address or delegated prefix to A contract by which the server grants the use of an address or
the client for a specified period of time. delegated prefix to the client for a specified period of time.
message A unit of data carried as the payload of a message
UDP datagram, exchanged among DHCP servers, A unit of data carried as the payload of a UDP datagram, exchanged
relay agents, and clients. among DHCP servers, relay agents, and clients.
Reconfigure key A key supplied to a client by a server. Reconfigure key
Used to provide security for Reconfigure A key supplied to a client by a server. Used to provide security
messages (see Section 7.3 for the list of for Reconfigure messages (see Section 7.3 for the list of
available message types). available message types).
relaying A DHCP relay agent relays DHCP messages relaying
between DHCP participants. A DHCP relay agent relays DHCP messages between DHCP participants.
retransmission Another attempt to send the same DHCP retransmission
message by a client or server, as a result Another attempt to send the same DHCP message by a client or
of not receiving a valid response to the server, as a result of not receiving a valid response to the
previously sent messages. The previously sent messages. The retransmitted message is typically
retransmitted message is typically modified modified prior to sending, as required by the DHCP specifications.
prior to sending, as required by the DHCP In particular, the client updates the value of the Elapsed Time
specifications. In particular, the client option in the retransmitted message.
updates the value of the Elapsed Time
option in the retransmitted message.
RKAP The Reconfiguration Key Authentication RKAP
Protocol (see Section 20.4). The Reconfiguration Key Authentication Protocol (see
Section 20.4).
singleton option An option that is allowed to appear only singleton option
once as a top-level option or at any An option that is allowed to appear only once as a top-level
encapsulation level. Most options are option or at any encapsulation level. Most options are
singletons. singletons.
T1 The time interval after which the client is T1
expected to contact the server that did the The time interval after which the client is expected to contact
assignment to extend (renew) the lifetimes the server that did the assignment to extend (renew) the lifetimes
of the addresses assigned (via IA_NA of the addresses assigned (via IA_NA option(s)) and/or prefixes
option(s)) and/or prefixes delegated (via delegated (via IA_PD option(s)) to the client. T1 is expressed as
IA_PD option(s)) to the client. T1 is an absolute value in messages (in seconds), is conveyed within IA
expressed as an absolute value in messages containers (currently the IA_NA and IA_PD options), and is
(in seconds), is conveyed within IA interpreted as a time interval since the message's reception. The
containers (currently the IA_NA and IA_PD value stored in the T1 field in IA options is referred to as the
options), and is interpreted as a time T1 value. The actual time when the timer expires is referred to
interval since the message's reception. as the T1 time.
The value stored in the T1 field in IA
options is referred to as the T1 value.
The actual time when the timer expires is
referred to as the T1 time.
T2 The time interval after which the client is T2
expected to contact any available server to The time interval after which the client is expected to contact
extend (rebind) the lifetimes of the any available server to extend (rebind) the lifetimes of the
addresses assigned (via IA_NA option(s)) addresses assigned (via IA_NA option(s)) and/or prefixes delegated
and/or prefixes delegated (via IA_PD (via IA_PD option(s)) to the client. T2 is expressed as an
option(s)) to the client. T2 is expressed absolute value in messages (in seconds), is conveyed within IA
as an absolute value in messages (in containers (currently the IA_NA and IA_PD options), and is
seconds), is conveyed within IA containers interpreted as a time interval since the message's reception. The
(currently the IA_NA and IA_PD options), value stored in the T2 field in IA options is referred to as the
and is interpreted as a time interval since T2 value. The actual time when the timer expires is referred to
the message's reception. The value stored as the T2 time.
in the T2 field in IA options is referred
to as the T2 value. The actual time when
the timer expires is referred to as the
T2 time.
top-level option An option conveyed in a DHCP message top-level option
directly, i.e., not encapsulated in any An option conveyed in a DHCP message directly, i.e., not
other option, as described in Section 9 of encapsulated in any other option, as described in Section 9 of
[RFC7227]. [RFC7227].
transaction ID An opaque value used to match responses transaction ID
with replies initiated by either a client An opaque value used to match responses with replies initiated by
or a server. either a client or a server.
5. Client/Server Exchanges 5. Client/Server Exchanges
Clients and servers exchange DHCP messages using UDP (see [RFC0768] Clients and servers exchange DHCP messages using UDP (see [RFC0768]
and [BCP145]). The client uses a link-local source address or and [BCP145]). The client uses a link-local source address or
addresses determined through other mechanisms for transmitting and addresses determined through other mechanisms for transmitting and
receiving DHCP messages. receiving DHCP messages.
A DHCP client sends all messages using a reserved, link-scoped A DHCP client sends all messages using a reserved, link-scoped
multicast destination address (All_DHCP_Relay_Agents_and_Servers - multicast destination address (All_DHCP_Relay_Agents_and_Servers -
skipping to change at page 16, line 21 skipping to change at line 708
interaction should be considered and documented as part of any future interaction should be considered and documented as part of any future
protocol extension. protocol extension.
6.1. Stateless DHCP 6.1. Stateless DHCP
Stateless DHCP can be used at any time, typically when a node Stateless DHCP can be used at any time, typically when a node
requires some missing or expired configuration information that is requires some missing or expired configuration information that is
available via DHCP. available via DHCP.
This is the simplest and most basic operation for DHCP and requires a This is the simplest and most basic operation for DHCP and requires a
client (and a server) to support only two messages -- client (and a server) to support only two messages -- Information-
Information-request and Reply. Note that DHCP servers and relay request and Reply. Note that DHCP servers and relay agents typically
agents typically also need to support the Relay-forward and also need to support the Relay-forward and Relay-reply messages to
Relay-reply messages to accommodate operation when clients and accommodate operation when clients and servers are not on the same
servers are not on the same link. link.
6.2. DHCP for Non-temporary Address Assignment 6.2. DHCP for Non-Temporary Address Assignment
This model of operation was the original motivation for DHCP. It is This model of operation was the original motivation for DHCP. It is
appropriate for situations where stateless address autoconfiguration appropriate for situations where stateless address autoconfiguration
alone is insufficient or impractical, e.g., because of network alone is insufficient or impractical, e.g., because of network
policy, additional requirements such as dynamic updates to the DNS, policy, additional requirements such as dynamic updates to the DNS,
or client-specific requirements. or client-specific requirements.
The model of operation for non-temporary address assignment is as The model of operation for non-temporary address assignment is as
follows: follows:
skipping to change at page 18, line 20 skipping to change at line 799
Each prefix has an associated preferred lifetime and valid lifetime Each prefix has an associated preferred lifetime and valid lifetime
(see Section 12.2), which constitute an agreement about the length of (see Section 12.2), which constitute an agreement about the length of
time over which the client is allowed to use the prefix. A client time over which the client is allowed to use the prefix. A client
can request an extension of the lifetimes on a delegated prefix and can request an extension of the lifetimes on a delegated prefix and
is required to terminate the use of a delegated prefix if the valid is required to terminate the use of a delegated prefix if the valid
lifetime of the prefix expires. lifetime of the prefix expires.
Figure 1 illustrates a network architecture in which prefix Figure 1 illustrates a network architecture in which prefix
delegation could be used. delegation could be used.
______________________ \ ______________________ \
/ \ \ / \ \
| ISP core network | \ | ISP core network | \
\__________ ___________/ | \__________ ___________/ |
| | | |
+-------+-------+ | +-------+-------+ |
| Aggregation | | ISP | Aggregation | | ISP
| device | | network | device | | network
+-------+-------+ | +-------+-------+ |
| / | /
|Network link to / |Network link to /
|subscriber premises / |subscriber premises /
| |
+-------+-------+ \ +------+--------+ \
| CPE | \ | CPE | \
| (DHCP client) | \ | (DHCP client) | \
+----+---+------+ | +----+---+------+ |
| | | Subscriber | | | Subscriber
---+-------------+-----+ +-----+------ | network ---+-------------+-----+ +-----+------ | network
| | | | | | | |
+----+-----+ +-----+----+ +----+-----+ | +----+-----+ +-----+----+ +----+-----+ |
|Subscriber| |Subscriber| |Subscriber| / |Subscriber| |Subscriber| |Subscriber| /
| PC | | PC | | PC | / | PC | | PC | | PC | /
+----------+ +----------+ +----------+ / +----------+ +----------+ +----------+ /
Figure 1: Prefix Delegation Network Figure 1: Prefix Delegation Network
In this example, the server (in the ISP core network or integrated in In this example, the server (in the ISP core network or integrated in
the aggregation device) is configured with a set of prefixes to be the aggregation device) is configured with a set of prefixes to be
used for assignment to customers at the time of each customer's first used for assignment to customers at the time of each customer's first
connection to the ISP service. The prefix delegation process begins connection to the ISP service. The prefix delegation process begins
when the client (CPE) requests configuration information through when the client (CPE) requests configuration information through
DHCP. The DHCP messages from the client are received by the server DHCP. The DHCP messages from the client are received by the server
via the aggregation device. When the server receives the request, it via the aggregation device. When the server receives the request, it
skipping to change at page 19, line 37 skipping to change at line 865
or a prefix derived from it is advertised for stateless address or a prefix derived from it is advertised for stateless address
autoconfiguration [RFC4862], the advertised preferred and valid autoconfiguration [RFC4862], the advertised preferred and valid
lifetimes MUST NOT exceed the corresponding remaining lifetimes of lifetimes MUST NOT exceed the corresponding remaining lifetimes of
the delegated prefix. the delegated prefix.
A client that has delegated any of the address space received through A client that has delegated any of the address space received through
DHCP Prefix Delegation MUST NOT issue a DHCP Release on the relevant DHCP Prefix Delegation MUST NOT issue a DHCP Release on the relevant
delegated prefix while any of the address space is outstanding. That delegated prefix while any of the address space is outstanding. That
includes addresses leased out by DHCPv6 (IA_NA), prefixes delegated includes addresses leased out by DHCPv6 (IA_NA), prefixes delegated
via DHCPv6-PD (IA_PD), and addresses autoconfigured by IPv6 Router via DHCPv6-PD (IA_PD), and addresses autoconfigured by IPv6 Router
Advertisements. Requirement WPD-9 in [RFC9096] makes this the Best Advertisements. Requirement WPD-9 in [RFC9096] makes this the best
Current Practice. current practice.
[RFC9096] section 3.3 further provides more guidance on coordination [RFC9096], Section 3.3 provides further guidance on coordination of
of lifetimes between WAN (DHCPv6-PD client) and LAN (DHCPv6-PD lifetimes between WAN (DHCPv6-PD client) and LAN (DHCPv6-PD server)
server) sides. sides.
Several problems related to Prefix Delegation and Relay Agents and a Several problems related to Prefix Delegation and Relay Agents and a
set of requirements to address them are defined in [RFC8987]. set of requirements to address them are defined in [RFC8987].
6.4. DHCP for Customer Edge Routers 6.4. DHCP for Customer Edge Routers
The DHCP requirements and network architecture for Customer Edge The DHCP requirements and network architecture for Customer Edge
Routers are described in [RFC7084], with improvements for renumbering Routers are described in [RFC7084], with improvements for renumbering
described in [RFC9096]. This model of operation combines address described in [RFC9096]. This model of operation combines address
assignment (see Section 6.2) and prefix delegation (see Section 6.3). assignment (see Section 6.2) and prefix delegation (see Section 6.3).
skipping to change at page 21, line 5 skipping to change at line 917
larger prefix in its initial transmissions rather than request larger prefix in its initial transmissions rather than request
additional prefixes later on. additional prefixes later on.
The exact behavior of the server (whether to grant additional The exact behavior of the server (whether to grant additional
addresses and prefixes or not) is up to the server policy and is out addresses and prefixes or not) is up to the server policy and is out
of scope for this document. of scope for this document.
For more information on how the server distinguishes between IA For more information on how the server distinguishes between IA
option instances, see Section 12. option instances, see Section 12.
6.6. Registering Self-generated Addresses 6.6. Registering Self-Generated Addresses
[RFC9686] introduces a method for devices to register their self- [RFC9686] introduces a method for devices to register their self-
generated or statically configured addresses in the DHCPv6 servers. generated or statically configured addresses in the DHCPv6 servers.
The general idea is that devices would notify the server about The general idea is that devices would notify the server about
addresses that they are using, so that the server can log or record addresses that they are using, so that the server can log or record
these addresses as required by local policy. these addresses as required by local policy.
The major specificity of this mechanism is that the address selection The major specificity of this mechanism is that the address selection
is not done by the DHCP server, but by the device itself. The most is not done by the DHCP server, but by the device itself. The
of the lifecycle remains the same in principle: a lease is created by majority of the lifecycle remains the same in principle: a lease is
the server, and the device performs periodic actions to get the lease created by the server, the device performs periodic actions to get
renewed, and eventually the lease can expire. However, this the lease renewed, and, eventually, the lease can expire. However,
mechanism uses different message types (ADDR-REG-INFORM and ADDR-REG- this mechanism uses different message types (ADDR-REG-INFORM and
REPLY) and has different source address requirements, as defined in ADDR-REG-REPLY) and has different source address requirements, as
[RFC9686]. defined in [RFC9686].
7. DHCP Constants 7. DHCP Constants
This section describes various program and networking constants used This section describes various program and networking constants used
by DHCP. by DHCP.
7.1. Multicast Addresses 7.1. Multicast Addresses
The following multicast addresses are used by DHCPv6: The following multicast addresses are used by DHCPv6:
skipping to change at page 22, line 27 skipping to change at line 985
of these rules for servers and relays agents. of these rules for servers and relays agents.
7.3. DHCP Message Types 7.3. DHCP Message Types
DHCP defines the following message types. The formats of these DHCP defines the following message types. The formats of these
messages are provided in Sections 8 and 9. Additional message types messages are provided in Sections 8 and 9. Additional message types
have been defined and may be defined in the future; see have been defined and may be defined in the future; see
<https://www.iana.org/assignments/dhcpv6-parameters>. The numeric <https://www.iana.org/assignments/dhcpv6-parameters>. The numeric
encoding for each message type is shown in parentheses. encoding for each message type is shown in parentheses.
SOLICIT (1) A client sends a Solicit message to locate SOLICIT (1)
servers. A client sends a Solicit message to locate servers.
ADVERTISE (2) A server sends an Advertise message to ADVERTISE (2)
indicate that it is available for DHCP A server sends an Advertise message to indicate that it is
service, in response to a Solicit message available for DHCP service, in response to a Solicit message
received from a client. received from a client.
REQUEST (3) A client sends a Request message to request REQUEST (3)
configuration parameters, including A client sends a Request message to request configuration
addresses and/or delegated prefixes, from a parameters, including addresses and/or delegated prefixes, from a
specific server. specific server.
CONFIRM (4) A client sends a Confirm message to any CONFIRM (4)
available server to determine whether the A client sends a Confirm message to any available server to
addresses it was assigned are still determine whether the addresses it was assigned are still
appropriate to the link to which the client appropriate to the link to which the client is connected.
is connected.
RENEW (5) A client sends a Renew message to the RENEW (5)
server that originally provided the A client sends a Renew message to the server that originally
client's leases and configuration provided the client's leases and configuration parameters to
parameters to extend the lifetimes on the extend the lifetimes on the leases assigned to the client and to
leases assigned to the client and to update update other configuration parameters.
other configuration parameters.
REBIND (6) A client sends a Rebind message to any REBIND (6)
available server to extend the lifetimes on A client sends a Rebind message to any available server to extend
the leases assigned to the client and to the lifetimes on the leases assigned to the client and to update
update other configuration parameters; this other configuration parameters; this message is sent after a
message is sent after a client receives no client receives no response to a Renew message.
response to a Renew message.
REPLY (7) A server sends a Reply message containing REPLY (7)
assigned leases and configuration A server sends a Reply message containing assigned leases and
parameters in response to a Solicit, configuration parameters in response to a Solicit, Request, Renew,
Request, Renew, or Rebind message received or Rebind message received from a client. A server sends a Reply
from a client. A server sends a Reply message containing configuration parameters in response to an
message containing configuration parameters Information-request message. A server sends a Reply message in
in response to an Information-request response to a Confirm message confirming or denying that the
message. A server sends a Reply message in addresses assigned to the client are appropriate to the link to
response to a Confirm message confirming or which the client is connected. A server sends a Reply message to
denying that the addresses assigned to the acknowledge receipt of a Release or Decline message.
client are appropriate to the link to which
the client is connected. A server sends a
Reply message to acknowledge receipt of a
Release or Decline message.
RELEASE (8) A client sends a Release message to the RELEASE (8)
server that assigned leases to the client A client sends a Release message to the server that assigned
to indicate that the client will no longer leases to the client to indicate that the client will no longer
use one or more of the assigned leases. use one or more of the assigned leases.
DECLINE (9) A client sends a Decline message to a DECLINE (9)
server to indicate that the client has A client sends a Decline message to a server to indicate that the
determined that one or more addresses client has determined that one or more addresses assigned by the
assigned by the server are already in use server are already in use on the link to which the client is
on the link to which the client is connected.
connected.
RECONFIGURE (10) A server sends a Reconfigure message to a RECONFIGURE (10)
client to inform the client that the server A server sends a Reconfigure message to a client to inform the
has new or updated configuration parameters client that the server has new or updated configuration parameters
and that the client is to initiate a and that the client is to initiate a Renew/Reply, Rebind/Reply, or
Renew/Reply, Rebind/Reply, or Information-request/Reply transaction with the server in order to
Information-request/Reply transaction with receive the updated information.
the server in order to receive the updated
information.
INFORMATION-REQUEST (11) A client sends an Information-request INFORMATION-REQUEST (11)
message to a server to request A client sends an Information-request message to a server to
configuration parameters without the request configuration parameters without the assignment of any
assignment of any leases to the client. leases to the client.
RELAY-FORW (12) A relay agent sends a Relay-forward message RELAY-FORW (12)
to relay messages to servers, either A relay agent sends a Relay-forward message to relay messages to
directly or through another relay agent. servers, either directly or through another relay agent. The
The received message -- either a client received message -- either a client message or a Relay-forward
message or a Relay-forward message from message from another relay agent -- is encapsulated in an option
another relay agent -- is encapsulated in in the Relay-forward message.
an option in the Relay-forward message.
RELAY-REPL (13) A server sends a Relay-reply message to a RELAY-REPL (13)
relay agent containing a message that the A server sends a Relay-reply message to a relay agent containing a
relay agent delivers to a client. The message that the relay agent delivers to a client. The Relay-
Relay-reply message may be relayed by other reply message may be relayed by other relay agents for delivery to
relay agents for delivery to the the destination relay agent.
destination relay agent.
The server encapsulates the client message The server encapsulates the client message as an option in the
as an option in the Relay-reply message, Relay-reply message, which the relay agent extracts and relays to
which the relay agent extracts and relays the client.
to the client.
7.4. DHCP Option Codes 7.4. DHCP Option Codes
DHCP makes extensive use of options in messages; some of these are DHCP makes extensive use of options in messages; some of these are
defined later, in Section 21. Additional options are defined in defined later, in Section 21. Additional options are defined in
other documents or may be defined in the future (see [RFC7227] for other documents or may be defined in the future (see [RFC7227] for
guidance on new option definitions). guidance on new option definitions).
7.5. Status Codes 7.5. Status Codes
skipping to change at page 27, line 12 skipping to change at line 1194
All values in the message header and in options are in network byte All values in the message header and in options are in network byte
order. order.
Options are stored serially in the "options" field, with no padding Options are stored serially in the "options" field, with no padding
between the options. Options are byte-aligned but are not aligned in between the options. Options are byte-aligned but are not aligned in
any other way (such as on 2-byte or 4-byte boundaries). any other way (such as on 2-byte or 4-byte boundaries).
The following diagram illustrates the format of DHCP messages sent The following diagram illustrates the format of DHCP messages sent
between clients and servers: between clients and servers:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| msg-type | transaction-id | | msg-type | transaction-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. options . . options .
. (variable number and length) . . (variable number and length) .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Client/Server Message Format Figure 2: Client/Server Message Format
msg-type Identifies the DHCP message type; the msg-type: Identifies the DHCP message type; the available message
available message types are listed in types are listed in Section 7.3. A 1-octet field.
Section 7.3. A 1-octet field.
transaction-id The transaction ID for this message exchange. transaction-id: The transaction ID for this message exchange. A
A 3-octet field. 3-octet field.
options Options carried in this message; options are options: Options carried in this message; options are described in
described in Section 21. A variable-length Section 21. A variable-length field (4 octets less than the size
field (4 octets less than the size of the of the message).
message).
9. Relay Agent/Server Message Formats 9. Relay Agent/Server Message Formats
Relay agents exchange messages with other relay agents and servers to Relay agents exchange messages with other relay agents and servers to
relay messages between clients and servers that are not connected to relay messages between clients and servers that are not connected to
the same link. the same link.
All values in the message header and in options are in network byte All values in the message header and in options are in network byte
order. order.
Options are stored serially in the "options" field, with no padding Options are stored serially in the "options" field, with no padding
between the options. Options are byte-aligned but are not aligned in between the options. Options are byte-aligned but are not aligned in
any other way (such as on 2-byte or 4-byte boundaries). any other way (such as on 2-byte or 4-byte boundaries).
There are two relay agent messages (Relay-forward and Relay-reply), There are two relay agent messages (Relay-forward and Relay-reply),
which share the following format: which share the following format:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| msg-type | hop-count | | | msg-type | hop-count | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | | |
| link-address | | link-address |
| | | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| | | | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | | |
| peer-address | | peer-address |
| | | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
| | | | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
. . . .
. options (variable number and length) .... . . options (variable number and length) .... .
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Relay Agent/Server Message Format Figure 3: Relay Agent/Server Message Format
The following sections describe the use of the relay agent message The following sections describe the use of the relay agent message
header. header.
9.1. Relay-forward Message 9.1. Relay-forward Message
The following table defines the use of message fields in a The following list defines the use of message fields in a Relay-
Relay-forward message. forward message.
msg-type RELAY-FORW (12). A 1-octet field. msg-type: RELAY-FORW (12). A 1-octet field.
hop-count Number of relay agents that have already hop-count: Number of relay agents that have already relayed this
relayed this message. A 1-octet field. message. A 1-octet field.
link-address An address that may be used by the server to link-address: An address that may be used by the server to identify
identify the link on which the client is the link on which the client is located. This is typically a
located. This is typically a globally scoped globally scoped unicast address (i.e., GUA or ULA), but see the
unicast address (i.e., GUA or ULA), but see discussion in Section 19.1.1. A 16-octet field.
the discussion in Section 19.1.1. A 16-octet
field.
peer-address The address of the client or relay agent from peer-address: The address of the client or relay agent from which
which the message to be relayed was received. the message to be relayed was received. A 16-octet field.
A 16-octet field.
options MUST include a Relay Message option (see options: MUST include a Relay Message option (see Section 21.10);
Section 21.10); MAY include other options, MAY include other options, such as the Interface-Id option (see
such as the Interface-Id option (see Section 21.18), added by the relay agent. A variable-length field
Section 21.18), added by the relay agent. A (34 octets less than the size of the message).
variable-length field (34 octets less than
the size of the message).
See Section 13.1 for an explanation of how the link-address field See Section 13.1 for an explanation of how the link-address field is
is used. used.
9.2. Relay-reply Message 9.2. Relay-reply Message
The following table defines the use of message fields in a The following list defines the use of message fields in a Relay-reply
Relay-reply message. message.
msg-type RELAY-REPL (13). A 1-octet field. msg-type: RELAY-REPL (13). A 1-octet field.
hop-count Copied from the Relay-forward message. hop-count: Copied from the Relay-forward message. A 1-octet field.
A 1-octet field.
link-address Copied from the Relay-forward message. link-address: Copied from the Relay-forward message. A 16-octet
A 16-octet field. field.
peer-address Copied from the Relay-forward message. peer-address: Copied from the Relay-forward message. A 16-octet
A 16-octet field. field.
options MUST include a Relay Message option (see options: MUST include a Relay Message option (see Section 21.10);
Section 21.10); MAY include other options, MAY include other options, such as the Interface-Id option (see
such as the Interface-Id option (see Section 21.18). A variable-length field (34 octets less than the
Section 21.18). A variable-length field size of the message).
(34 octets less than the size of the
message).
10. Representation and Use of Domain Names 10. Representation and Use of Domain Names
So that domain names may be encoded uniformly, a domain name or a So that domain names may be encoded uniformly, a domain name or a
list of domain names is encoded using the technique described in list of domain names is encoded using the technique described in
Section 3.1 of [RFC1035]. The message compression scheme in Section 3.1 of [RFC1035]. The message compression scheme in
Section 4.1.4 of [RFC1035] MUST NOT be used. Section 4.1.4 of [RFC1035] MUST NOT be used.
11. DHCP Unique Identifier (DUID) 11. DHCP Unique Identifier (DUID)
skipping to change at page 30, line 15 skipping to change at line 1332
Clients and servers MUST treat DUIDs as opaque values and MUST only Clients and servers MUST treat DUIDs as opaque values and MUST only
compare DUIDs for equality. Clients and servers SHOULD NOT in any compare DUIDs for equality. Clients and servers SHOULD NOT in any
other way interpret DUIDs. Clients and servers MUST NOT restrict other way interpret DUIDs. Clients and servers MUST NOT restrict
DUIDs to the types defined in this document, as additional DUID types DUIDs to the types defined in this document, as additional DUID types
may be defined in the future. It should be noted that an attempt to may be defined in the future. It should be noted that an attempt to
parse a DUID to obtain a client's link-layer address is unreliable, parse a DUID to obtain a client's link-layer address is unreliable,
as there is no guarantee that the client is still using the same as there is no guarantee that the client is still using the same
link-layer address as when it generated its DUID. Also, such an link-layer address as when it generated its DUID. Also, such an
attempt will be more and more unreliable as more clients adopt attempt will be more and more unreliable as more clients adopt
privacy measures such as those defined in [RFC7844]. If this privacy measures such as those defined in [RFC7844]. If this
capability is required, it is recommended to rely on the Client capability is required, it is recommended to rely on the Client Link-
Link-Layer Address option instead [RFC6939]. Layer Address option instead [RFC6939].
The DUID is carried in an option because it may be variable in length The DUID is carried in an option because it may be variable in length
and because it is not required in all DHCP messages. The DUID is and because it is not required in all DHCP messages. The DUID is
designed to be unique across all DHCP clients and servers, and stable designed to be unique across all DHCP clients and servers, and stable
for any specific client or server. That is, the DUID used by a for any specific client or server. That is, the DUID used by a
client or server SHOULD NOT change over time if at all possible; for client or server SHOULD NOT change over time if at all possible; for
example, a device's DUID should not change as a result of a change in example, a device's DUID should not change as a result of a change in
the device's network hardware or changes to virtual interfaces (e.g., the device's network hardware or changes to virtual interfaces (e.g.,
logical PPP (over Ethernet) interfaces that may come and go in logical PPP (over Ethernet) interfaces that may come and go in
Customer Premises Equipment routers). The client may change its DUID Customer Premises Equipment routers). The client may change its DUID
skipping to change at page 31, line 40 skipping to change at line 1396
DUID is generated. The time value is the time that the DUID is DUID is generated. The time value is the time that the DUID is
generated, represented in seconds since midnight (UTC), January 1, generated, represented in seconds since midnight (UTC), January 1,
2000, modulo 2^32. The hardware type MUST be a valid hardware type 2000, modulo 2^32. The hardware type MUST be a valid hardware type
assigned by IANA; see [IANA-HARDWARE-TYPES]. Both the time and the assigned by IANA; see [IANA-HARDWARE-TYPES]. Both the time and the
hardware type are stored in network byte order. For Ethernet hardware type are stored in network byte order. For Ethernet
hardware types, the link-layer address is stored in canonical form, hardware types, the link-layer address is stored in canonical form,
as described in [RFC2464]. as described in [RFC2464].
The following diagram illustrates the format of a DUID-LLT: The following diagram illustrates the format of a DUID-LLT:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DUID-Type (1) | hardware type (16 bits) | | DUID-Type (1) | hardware type (16 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| time (32 bits) | | time (32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. link-layer address (variable length) . . link-layer address (variable length) .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: DUID-LLT Format Figure 4: DUID-LLT Format
The choice of network interface can be completely arbitrary, as long The choice of network interface can be completely arbitrary, as long
as that interface provides a globally unique link-layer address for as that interface provides a globally unique link-layer address for
the link type; the same DUID-LLT SHOULD be used in configuring all the link type; the same DUID-LLT SHOULD be used in configuring all
network interfaces connected to the device, regardless of which network interfaces connected to the device, regardless of which
interface's link-layer address was used to generate the DUID-LLT. interface's link-layer address was used to generate the DUID-LLT.
Clients and servers using this type of DUID MUST store the DUID-LLT Clients and servers using this type of DUID MUST store the DUID-LLT
skipping to change at page 33, line 5 skipping to change at line 1452
DUID-LLT. DUID-LLT.
11.3. DUID Assigned by Vendor Based on Enterprise Number (DUID-EN) 11.3. DUID Assigned by Vendor Based on Enterprise Number (DUID-EN)
The vendor assigns this form of DUID to the device. This DUID The vendor assigns this form of DUID to the device. This DUID
consists of the 4-octet vendor's registered Private Enterprise Number consists of the 4-octet vendor's registered Private Enterprise Number
as maintained by IANA [IANA-PEN] followed by a unique identifier as maintained by IANA [IANA-PEN] followed by a unique identifier
assigned by the vendor. The following diagram summarizes the assigned by the vendor. The following diagram summarizes the
structure of a DUID-EN: structure of a DUID-EN:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DUID-Type (2) | enterprise-number | | DUID-Type (2) | enterprise-number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| enterprise-number (contd) | | | enterprise-number (contd) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
. identifier . . identifier .
. (variable length) . . (variable length) .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: DUID-EN Format Figure 5: DUID-EN Format
The source of the identifier is left up to the vendor defining it, The source of the identifier is left up to the vendor defining it,
but each identifier part of each DUID-EN MUST be unique to the device but each identifier part of each DUID-EN MUST be unique to the device
that is using it, and MUST be assigned to the device no later than at that is using it, and MUST be assigned to the device no later than at
the first usage and stored in some form of non-volatile storage. the first usage and stored in some form of non-volatile storage.
This typically means being assigned during the manufacturing process This typically means being assigned during the manufacturing process
in the case of physical devices or, in the case of virtual machines, in the case of physical devices or, in the case of virtual machines,
when the image is created or booted for the first time. The when the image is created or booted for the first time. The
generated DUID SHOULD be recorded in non-erasable storage. The generated DUID SHOULD be recorded in non-erasable storage. The
enterprise-number is the vendor's registered Private Enterprise enterprise-number is the vendor's registered Private Enterprise
Number as maintained by IANA [IANA-PEN]. The enterprise-number is Number as maintained by IANA [IANA-PEN]. The enterprise-number is
stored as an unsigned 32-bit number. stored as an unsigned 32-bit number.
An example DUID of this type might look like this: An example DUID of this type might look like this:
+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+
| 0 | 2 | 0 | 0 |126|217| 12|192| | 0 | 2 | 0 | 0 |126|217| 12|192|
+---+---+---+---+---+---+---+---+ +---+---+---+---+---+---+---+---+
|132|211| 3 | 0 | 9 | 18| |132|211| 3 | 0 | 9 | 18|
+---+---+---+---+---+---+ +---+---+---+---+---+---+
Figure 6: DUID-EN Example Figure 6: DUID-EN Example
This example includes the 2-octet type of 2 and the Enterprise Number This example includes the 2-octet type of 2 and the Enterprise Number
(32473) (from [RFC5612]), followed by 8 octets of identifier data (32473) (from [RFC5612]), followed by 8 octets of identifier data
(0x0CC084D303000912). (0x0CC084D303000912).
11.4. DUID Based on Link-Layer Address (DUID-LL) 11.4. DUID Based on Link-Layer Address (DUID-LL)
This type of DUID consists of 2 octets containing a DUID type of 3 This type of DUID consists of 2 octets containing a DUID type of 3
and a 2-octet network hardware type code, followed by the link-layer and a 2-octet network hardware type code, followed by the link-layer
address of any one network interface that is permanently connected to address of any one network interface that is permanently connected to
the client or server device. For example, a node that has a network the client or server device. For example, a node that has a network
interface implemented in a chip that is unlikely to be removed and interface implemented in a chip that is unlikely to be removed and
used elsewhere could use a DUID-LL. The hardware type MUST be a used elsewhere could use a DUID-LL. The hardware type MUST be a
valid hardware type assigned by IANA; see [IANA-HARDWARE-TYPES]. The valid hardware type assigned by IANA; see [IANA-HARDWARE-TYPES]. The
hardware type is stored in network byte order. The link-layer hardware type is stored in network byte order. The link-layer
address is stored in canonical form, as described in [RFC2464]. The address is stored in canonical form, as described in [RFC2464]. The
following diagram illustrates the format of a DUID-LL: following diagram illustrates the format of a DUID-LL:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DUID-Type (3) | hardware type (16 bits) | | DUID-Type (3) | hardware type (16 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. link-layer address (variable length) . . link-layer address (variable length) .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: DUID-LL Format Figure 7: DUID-LL Format
The choice of network interface can be completely arbitrary, as long The choice of network interface can be completely arbitrary, as long
as that interface provides a unique link-layer address and is as that interface provides a unique link-layer address and is
permanently attached to the device on which the DUID-LL is being permanently attached to the device on which the DUID-LL is being
generated. The same DUID-LL SHOULD be used in configuring all generated. The same DUID-LL SHOULD be used in configuring all
network interfaces connected to the device, regardless of which network interfaces connected to the device, regardless of which
interface's link-layer address was used to generate the DUID. interface's link-layer address was used to generate the DUID.
skipping to change at page 34, line 41 skipping to change at line 1537
by DHCP clients or servers that cannot tell whether or not a network by DHCP clients or servers that cannot tell whether or not a network
interface is permanently attached to the device on which the DHCP interface is permanently attached to the device on which the DHCP
client is running. client is running.
11.5. DUID Based on Universally Unique Identifier (DUID-UUID) 11.5. DUID Based on Universally Unique Identifier (DUID-UUID)
This type of DUID consists of 16 octets containing a 128-bit UUID. This type of DUID consists of 16 octets containing a 128-bit UUID.
[RFC6355] details when to use this type and how to pick an [RFC6355] details when to use this type and how to pick an
appropriate source of the UUID. appropriate source of the UUID.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DUID-Type (4) | UUID (128 bits) | | DUID-Type (4) | UUID (128 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | | |
| | | |
| -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
Figure 8: DUID-UUID Format Figure 8: DUID-UUID Format
12. Identity Association 12. Identity Association
An Identity Association (IA) is a construct through which a server An Identity Association (IA) is a construct through which a server
and a client can identify, group, and manage a set of related IPv6 and a client can identify, group, and manage a set of related IPv6
addresses or delegated prefixes. Each IA consists of an IAID and addresses or delegated prefixes. Each IA consists of an IAID and
associated configuration information. associated configuration information.
The IAID uniquely identifies the IA and MUST be chosen to be unique The IAID uniquely identifies the IA and MUST be chosen to be unique
skipping to change at page 38, line 8 skipping to change at line 1698
A client uses multicast to reach all servers or an individual server. A client uses multicast to reach all servers or an individual server.
An individual server is indicated by specifying that server's DUID in An individual server is indicated by specifying that server's DUID in
a Server Identifier option (see Section 21.3) in the client's a Server Identifier option (see Section 21.3) in the client's
message. (All servers will receive this message, but only the message. (All servers will receive this message, but only the
indicated server will respond.) All servers are indicated when this indicated server will respond.) All servers are indicated when this
option is not supplied. option is not supplied.
14.1. Rate Limiting 14.1. Rate Limiting
A DHCPv6 client MUST limit the rate of DHCP messages it transmits or A DHCPv6 client MUST limit the rate of DHCP messages it transmits or
retransmits. This will minimise the impact of prolonged message retransmits. This will minimize the impact of prolonged message
bursts or loops, for example when a client rejects a server's bursts or loops, for example when a client rejects a server's
response, repeats the request and gets the same server response which response, repeats the request and gets the same server response,
again gets rejected by the client. which, again, gets rejected by the client.
This loop can repeat infinitely if there is not a quit/stop This loop can repeat infinitely if there is not a quit/stop
mechanism. Therefore, a client must not initiate transmissions too mechanism. Therefore, a client must not initiate transmissions too
frequently. frequently.
A recommended method for implementing the rate-limiting function is a A recommended method for implementing the rate-limiting function is a
token bucket (see Appendix A of [RFC3290]), limiting the average rate token bucket (see Appendix A of [RFC3290]), limiting the average rate
of transmission to a certain number in a certain time interval. This of transmission to a certain number in a certain time interval. This
method of bounding burstiness also guarantees that the long-term method of bounding burstiness also guarantees that the long-term
transmission rate will not be exceeded. transmission rate will not be exceeded.
skipping to change at page 39, line 45 skipping to change at line 1777
options (see Section 21.6) or IA Prefix options (see Section 21.22) options (see Section 21.6) or IA Prefix options (see Section 21.22)
if a valid lifetime for any of the client's leases expires before if a valid lifetime for any of the client's leases expires before
retransmission. Thus, whenever this document refers to a retransmission. Thus, whenever this document refers to a
"retransmission" of a client's message, it refers to both modifying "retransmission" of a client's message, it refers to both modifying
the original message and sending this new message instance to the the original message and sending this new message instance to the
server. server.
The client retransmission behavior is controlled and described by the The client retransmission behavior is controlled and described by the
following variables: following variables:
RT Retransmission timeout RT: Retransmission timeout
IRT Initial retransmission time IRT: Initial retransmission time
MRC Maximum retransmission count MRC: Maximum retransmission count
MRT Maximum retransmission time MRT: Maximum retransmission time
MRD Maximum retransmission duration
RAND Randomization factor MRD: Maximum retransmission duration
RAND: Randomization factor
Specific values for each of these parameters relevant to the various Specific values for each of these parameters relevant to the various
messages are given in the subsections of Section 18.2, using values messages are given in the subsections of Section 18.2, using values
defined in Table 1 in Section 7.6. The algorithm for RAND is common defined in Table 1 in Section 7.6. The algorithm for RAND is common
across all message transmissions. across all message transmissions.
With each message transmission or retransmission, the client sets RT With each message transmission or retransmission, the client sets RT
according to the rules given below. If RT expires before the message according to the rules given below. If RT expires before the message
exchange terminates, the client recomputes RT and retransmits the exchange terminates, the client recomputes RT and retransmits the
message. message.
skipping to change at page 41, line 6 skipping to change at line 1834
MRC specifies an upper bound on the number of times a client may MRC specifies an upper bound on the number of times a client may
retransmit a message. Unless MRC is zero, the message exchange fails retransmit a message. Unless MRC is zero, the message exchange fails
once the client has transmitted the message MRC times. once the client has transmitted the message MRC times.
MRD specifies an upper bound on the length of time a client may MRD specifies an upper bound on the length of time a client may
retransmit a message. Unless MRD is zero, the message exchange fails retransmit a message. Unless MRD is zero, the message exchange fails
once MRD seconds have elapsed since the client first transmitted the once MRD seconds have elapsed since the client first transmitted the
message. message.
If both MRC and MRD are non-zero, the message exchange fails whenever If both MRC and MRD are non-zero, the message exchange fails whenever
either of the conditions specified in the previous two paragraphs either of the conditions specified in the previous two paragraphs is
is met. met.
If both MRC and MRD are zero, the client continues to transmit the If both MRC and MRD are zero, the client continues to transmit the
message until it receives a response. message until it receives a response.
A client is not expected to listen for a response during the entire A client is not expected to listen for a response during the entire
RT period and may turn off listening capabilities after waiting at RT period and may turn off listening capabilities after waiting at
least the shorter of RT and MAX_WAIT_TIME due to power consumption least the shorter of RT and MAX_WAIT_TIME due to power consumption
saving or other reasons. Of course, a client MUST listen for a saving or other reasons. Of course, a client MUST listen for a
Reconfigure if it has negotiated for its use with the server. Reconfigure if it has negotiated for its use with the server.
16. Message Validation 16. Message Validation
This section describes which options are valid in which kinds of This section describes which options are valid in which kinds of
message types and explains what to do when a client or server message types and explains what to do when a client or server
receives a message that contains known options that are invalid for receives a message that contains known options that are invalid for
that message. For example, an IA option is not allowed to appear in that message. For example, an IA option is not allowed to appear in
an Information-request message. an Information-request message.
Clients and servers MAY choose to either (1) extract information from Clients and servers MAY choose to either (1) extract information from
such a message if the information is of use to the recipient or such a message if the information is of use to the recipient or (2)
(2) ignore such a message completely and just discard it. ignore such a message completely and just discard it.
If a server receives a message that it considers invalid, it MAY send If a server receives a message that it considers invalid, it MAY send
a Reply message (or Advertise message, as appropriate) with a Server a Reply message (or Advertise message, as appropriate) with a Server
Identifier option (see Section 21.3), a Client Identifier option (see Identifier option (see Section 21.3), a Client Identifier option (see
Section 21.2) (if one was included in the message), and a Status Code Section 21.2) (if one was included in the message), and a Status Code
option (see Section 21.13) with status UnspecFail. option (see Section 21.13) with status UnspecFail.
Clients, relay agents, and servers MUST NOT discard messages that Clients, relay agents, and servers MUST NOT discard messages that
contain unknown options (or instances of vendor options with unknown contain unknown options (or instances of vendor options with unknown
enterprise-number values). These options should be ignored as if enterprise-number values). These options should be ignored as if
they were not present. This is critical to provide for future they were not present. This is critical to provide for future
extensions of DHCP. extensions of DHCP.
A client or server MUST discard any received DHCP messages with an A client or server MUST discard any received DHCP messages with an
unknown message type. unknown message type.
Clients SHOULD NOT accept multicast messages. Clients SHOULD NOT accept multicast messages.
Servers SHOULD NOT accept unicast traffic from clients. The Server Servers SHOULD NOT accept unicast traffic from clients. The Server
Unicast option (see Section 21.12) and UseMulticast status code (see Unicast option (see Section 21.12) and UseMulticast status code (see
Section 21.13) have been obsoleted and hence clients should no longer Section 21.13) have been obsoleted; hence, clients should no longer
send messages to a server's unicast address nor receive the send messages to a server's unicast address nor receive the
UseMulticast status code. However, a server that previously UseMulticast status code. However, a server that previously
supported the Server Unicast option and is upgraded to not support supported the Server Unicast option and is upgraded to not support it
it, MAY continue to receive unicast messages if it previously sent MAY continue to receive unicast messages if it previously sent the
the client the Server Unicast option. But this causes no harm and client the Server Unicast option. However, this causes no harm and
the client will eventually switch back to sending multicast messages the client will eventually switch back to sending multicast messages
(such as after the lease's rebinding time is reached or the client is (such as after the lease's rebinding time is reached or the client is
rebooted). rebooted).
Relay agents SHOULD NOT accept unicast messages from clients. Relay agents SHOULD NOT accept unicast messages from clients.
Note: The multicast/unicast rules mentioned above apply to the DHCP Note: The multicast/unicast rules mentioned above apply to the DHCP
messages within this document. Messages defined in other and future messages within this document. Messages defined in other and future
documents may have different rules. documents may have different rules.
skipping to change at page 48, line 20 skipping to change at line 2182
If the server responds with an Advertise message, the client If the server responds with an Advertise message, the client
initiates a configuration exchange as described in Section 18.2.2. initiates a configuration exchange as described in Section 18.2.2.
A server may initiate a message exchange with a client by sending a A server may initiate a message exchange with a client by sending a
Reconfigure message to cause the client to send a Renew, Rebind, or Reconfigure message to cause the client to send a Renew, Rebind, or
Information-request message to refresh its configuration information Information-request message to refresh its configuration information
as soon as the Reconfigure message is received by the client. as soon as the Reconfigure message is received by the client.
Figure 9 shows a timeline diagram of the messages exchanged between a Figure 9 shows a timeline diagram of the messages exchanged between a
client and two servers for the typical lifecycle of one or more client and two servers for the typical lifecycle of one or more
leases. This starts with the four-message Solicit/Advertise/ leases. This starts with the four-message Solicit/Advertise/Request/
Request/Reply exchange to obtain the lease(s), followed by a Reply exchange to obtain the lease(s), followed by a two-message
two-message Renew/Reply exchange to extend the lifetime on the Renew/Reply exchange to extend the lifetime on the lease(s), and then
lease(s), and then ends with a two-message Release/Reply exchange to ends with a two-message Release/Reply exchange to end the client's
end the client's use of the lease(s). use of the lease(s).
Server Server Server Server
(not selected) Client (selected) (not selected) Client (selected)
v v v v v v
| | | | | |
| Begins initialization | | Begins initialization |
| | | | | |
start of | _____________/|\_____________ | start of | _____________/|\_____________ |
4-message |/ Solicit | Solicit \| 4-message |/ Solicit | Solicit \|
skipping to change at page 49, line 34 skipping to change at line 2245
2-message | _____________/|\_____________ | 2-message | _____________/|\_____________ |
exchange |/ Release | Release \| exchange |/ Release | Release \|
| | | | | |
| | Discards lease(s) | | Discards lease(s)
| | | | | |
| | _____________/| | | _____________/|
| |/ Reply | | |/ Reply |
| | | | | |
v v v v v v
Figure 9: Timeline Diagram of the Messages Exchanged between a Figure 9: Timeline Diagram of the Messages Exchanged Between a
Client and Two Servers for the Typical Lifecycle of One or More Client and Two Servers for the Typical Lifecycle of One or More
Leases Leases
18.1. A Single Exchange for Multiple IA Options 18.1. A Single Exchange for Multiple IA Options
This document assumes that a client SHOULD use a single transaction This document assumes that a client SHOULD use a single transaction
for all of the IA options required on an interface; this simplifies for all of the IA options required on an interface; this simplifies
the client implementation and reduces the potential number of the client implementation and reduces the potential number of
transactions required. To facilitate a client's use of a single transactions required. To facilitate a client's use of a single
transaction for all IA options, servers MUST return the same T1/T2 transaction for all IA options, servers MUST return the same T1/T2
skipping to change at page 51, line 50 skipping to change at line 2355
The first Solicit message from the client on the interface SHOULD be The first Solicit message from the client on the interface SHOULD be
delayed by a random amount of time between 0 and SOL_MAX_DELAY. This delayed by a random amount of time between 0 and SOL_MAX_DELAY. This
random delay helps desynchronize clients that start a DHCP session at random delay helps desynchronize clients that start a DHCP session at
the same time, such as after recovery from a power failure or after a the same time, such as after recovery from a power failure or after a
router outage after seeing that DHCP is available in Router router outage after seeing that DHCP is available in Router
Advertisement messages (see Section 4.2 of [RFC4861]). Advertisement messages (see Section 4.2 of [RFC4861]).
The client transmits the message according to Section 15, using the The client transmits the message according to Section 15, using the
following parameters: following parameters:
IRT SOL_TIMEOUT * IRT: SOL_TIMEOUT
MRT SOL_MAX_RT * MRT: SOL_MAX_RT
MRC 0
MRD 0 * MRC: 0
* MRD: 0
A client that wishes to use the Rapid Commit two-message exchange A client that wishes to use the Rapid Commit two-message exchange
includes a Rapid Commit option (see Section 21.14) in its Solicit includes a Rapid Commit option (see Section 21.14) in its Solicit
message. The client may receive a number of different replies from message. The client may receive a number of different replies from
different servers. The client will make note of any valid Advertise different servers. The client will make note of any valid Advertise
messages that it receives. The client will discard any Reply messages that it receives. The client will discard any Reply
messages that do not contain the Rapid Commit option. messages that do not contain the Rapid Commit option.
Upon receipt of a valid Reply with the Rapid Commit option, the Upon receipt of a valid Reply with the Rapid Commit option, the
client processes the message as described in Section 18.2.10. client processes the message as described in Section 18.2.10.
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If the client is waiting for an Advertise message, the mechanism If the client is waiting for an Advertise message, the mechanism
described in Section 15 is modified as follows for use in the described in Section 15 is modified as follows for use in the
transmission of Solicit messages. The message exchange is not transmission of Solicit messages. The message exchange is not
terminated by the receipt of an Advertise before the first RT has terminated by the receipt of an Advertise before the first RT has
elapsed. Rather, the client collects valid Advertise messages until elapsed. Rather, the client collects valid Advertise messages until
the first RT has elapsed. Also, the first RT MUST be selected to be the first RT has elapsed. Also, the first RT MUST be selected to be
strictly greater than IRT by choosing RAND to be strictly greater strictly greater than IRT by choosing RAND to be strictly greater
than 0. than 0.
A client MUST collect valid Advertise messages for the first A client MUST collect valid Advertise messages for the first RT
RT seconds, unless it receives a valid Advertise message with a seconds, unless it receives a valid Advertise message with a
preference value of 255. The preference value is carried in the preference value of 255. The preference value is carried in the
Preference option (see Section 21.8). Any valid Advertise that does Preference option (see Section 21.8). Any valid Advertise that does
not include a Preference option is considered to have a preference not include a Preference option is considered to have a preference
value of 0. If the client receives a valid Advertise message that value of 0. If the client receives a valid Advertise message that
includes a Preference option with a preference value of 255, the includes a Preference option with a preference value of 255, the
client immediately begins a client-initiated message exchange (as client immediately begins a client-initiated message exchange (as
described in Section 18.2.2) by sending a Request message to the described in Section 18.2.2) by sending a Request message to the
server from which the Advertise message was received. If the client server from which the Advertise message was received. If the client
receives a valid Advertise message that does not include a Preference receives a valid Advertise message that does not include a Preference
option with a preference value of 255, the client continues to wait option with a preference value of 255, the client continues to wait
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in the Option Request option, with data values as hints to the server in the Option Request option, with data values as hints to the server
about parameter values the client would like to have returned. about parameter values the client would like to have returned.
The client includes a Reconfigure Accept option (see Section 21.20) The client includes a Reconfigure Accept option (see Section 21.20)
if the client is willing to accept Reconfigure messages from the if the client is willing to accept Reconfigure messages from the
server. server.
The client transmits the message according to Section 15, using the The client transmits the message according to Section 15, using the
following parameters: following parameters:
IRT REQ_TIMEOUT * IRT: REQ_TIMEOUT
MRT REQ_MAX_RT * MRT: REQ_MAX_RT
MRC REQ_MAX_RC * MRC: REQ_MAX_RC
MRD 0 * MRD: 0
If the message exchange fails, the client takes an action based on If the message exchange fails, the client takes an action based on
the client's local policy. Examples of actions the client might take the client's local policy. Examples of actions the client might take
include the following: include the following:
* Select another server from a list of servers known to the client * Select another server from a list of servers known to the client
-- for example, servers that responded with an Advertise message. -- for example, servers that responded with an Advertise message.
* Initiate the server discovery process described in Section 18. * Initiate the server discovery process described in Section 18.
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to identify itself to the server. to identify itself to the server.
The client MUST include an Elapsed Time option (see Section 21.9) to The client MUST include an Elapsed Time option (see Section 21.9) to
indicate how long the client has been trying to complete the current indicate how long the client has been trying to complete the current
DHCP message exchange. DHCP message exchange.
The client includes IA options for all of the IAs assigned to the The client includes IA options for all of the IAs assigned to the
interface for which the Confirm message is being sent. The IA interface for which the Confirm message is being sent. The IA
options include all of the addresses the client currently has options include all of the addresses the client currently has
associated with those IAs. The client SHOULD set the T1 and T2 associated with those IAs. The client SHOULD set the T1 and T2
fields in any IA_NA options (see Section 21.4) and the fields in any IA_NA options (see Section 21.4) and the preferred-
preferred-lifetime and valid-lifetime fields in the IA Address lifetime and valid-lifetime fields in the IA Address options (see
options (see Section 21.6) to 0, as the server will ignore these Section 21.6) to 0, as the server will ignore these fields.
fields.
The first Confirm message from the client on the interface MUST be The first Confirm message from the client on the interface MUST be
delayed by a random amount of time between 0 and CNF_MAX_DELAY. The delayed by a random amount of time between 0 and CNF_MAX_DELAY. The
client transmits the message according to Section 15, using the client transmits the message according to Section 15, using the
following parameters: following parameters:
IRT CNF_TIMEOUT * IRT: CNF_TIMEOUT
MRT CNF_MAX_RT * MRT: CNF_MAX_RT
MRC 0 * MRC: 0
MRD CNF_MAX_RD * MRD: CNF_MAX_RD
If the client receives no responses before the message transmission If the client receives no responses before the message transmission
process terminates, as described in Section 15, the client SHOULD process terminates, as described in Section 15, the client SHOULD
continue to use any leases, using the last known lifetimes for those continue to use any leases, using the last known lifetimes for those
leases, and SHOULD continue to use any other previously obtained leases, and SHOULD continue to use any other previously obtained
configuration parameters. configuration parameters.
18.2.4. Creation and Transmission of Renew Messages 18.2.4. Creation and Transmission of Renew Messages
To extend the preferred and valid lifetimes for the leases assigned To extend the preferred and valid lifetimes for the leases assigned
skipping to change at page 55, line 47 skipping to change at line 2544
the client sends a Renew message to the server from which the leases the client sends a Renew message to the server from which the leases
were obtained; the Renew message includes IA options for the IAs were obtained; the Renew message includes IA options for the IAs
whose lease lifetimes are to be extended. The client includes IA whose lease lifetimes are to be extended. The client includes IA
Address options (see Section 21.6) within IA_NA (see Section 21.4) Address options (see Section 21.6) within IA_NA (see Section 21.4)
options for the addresses assigned to the IAs. The client includes options for the addresses assigned to the IAs. The client includes
IA Prefix options (see Section 21.22) within IA_PD options (see IA Prefix options (see Section 21.22) within IA_PD options (see
Section 21.21) for the delegated prefixes assigned to the IAs. Section 21.21) for the delegated prefixes assigned to the IAs.
The server controls the time at which the client should contact the The server controls the time at which the client should contact the
server to extend the lifetimes on assigned leases through the T1 and server to extend the lifetimes on assigned leases through the T1 and
T2 values assigned to an IA. However, as the client SHOULD T2 values assigned to an IA. However, as the client SHOULD renew/
renew/rebind all IAs from the server at the same time, the client rebind all IAs from the server at the same time, the client MUST
MUST select T1 and T2 times from all IA options that will guarantee select T1 and T2 times from all IA options that will guarantee that
that the client initiates transmissions of Renew/Rebind messages not the client initiates transmissions of Renew/Rebind messages not later
later than at the T1/T2 times associated with any of the client's than at the T1/T2 times associated with any of the client's bindings
bindings (earliest T1/T2). (earliest T1/T2).
At time T1, the client initiates a Renew/Reply message exchange to At time T1, the client initiates a Renew/Reply message exchange to
extend the lifetimes on any leases in the IA. extend the lifetimes on any leases in the IA.
A client MUST also initiate a Renew/Reply message exchange before A client MUST also initiate a Renew/Reply message exchange before
time T1 if the client's link-local address used in previous time T1 if the client's link-local address used in previous
interactions with the server is no longer valid and it is willing to interactions with the server is no longer valid and it is willing to
receive Reconfigure messages. This updates the server's information receive Reconfigure messages. This updates the server's information
so it is able to continue to communicate with the client (either so it is able to continue to communicate with the client (either
directly or via Relay-reply's). directly or via Relay-reply messages).
If T1 or T2 had been set to 0 by the server (for an IA_NA or IA_PD) If T1 or T2 had been set to 0 by the server (for an IA_NA or IA_PD)
in a previous Reply, the client may, at its discretion, send a Renew in a previous Reply, the client may, at its discretion, send a Renew
or Rebind message, respectively. The client MUST follow the rules or Rebind message, respectively. The client MUST follow the rules
defined in Section 14.2. defined in Section 14.2.
The client sets the "msg-type" field to RENEW. The client generates The client sets the "msg-type" field to RENEW. The client generates
a transaction ID and inserts this value in the "transaction-id" a transaction ID and inserts this value in the "transaction-id"
field. field.
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The client includes an Option Request option (see Section 21.7) to The client includes an Option Request option (see Section 21.7) to
request the SOL_MAX_RT option (see Section 21.24) and any other request the SOL_MAX_RT option (see Section 21.24) and any other
options the client is interested in receiving. The client MAY options the client is interested in receiving. The client MAY
include options with data values as hints to the server about include options with data values as hints to the server about
parameter values the client would like to have returned. parameter values the client would like to have returned.
The client transmits the message according to Section 15, using the The client transmits the message according to Section 15, using the
following parameters: following parameters:
IRT REN_TIMEOUT * IRT: REN_TIMEOUT
MRT REN_MAX_RT * MRT: REN_MAX_RT
MRC 0 * MRC: 0
MRD Remaining time until earliest T2 * MRD: Remaining time until earliest T2
The message exchange is terminated when the earliest time T2 is The message exchange is terminated when the earliest time T2 is
reached. While the client is responding to a Reconfigure, the client reached. While the client is responding to a Reconfigure, the client
ignores and discards any additional Reconfigure messages it may ignores and discards any additional Reconfigure messages it may
receive. receive.
The message exchange is terminated when the earliest time T2 is The message exchange is terminated when the earliest time T2 is
reached, at which point the client begins the Rebind message exchange reached, at which point the client begins the Rebind message exchange
(see Section 18.2.5). (see Section 18.2.5).
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Section 18.2.4, with the following differences: Section 18.2.4, with the following differences:
* The client sets the "msg-type" field to REBIND. * The client sets the "msg-type" field to REBIND.
* The client does not include the Server Identifier option (see * The client does not include the Server Identifier option (see
Section 21.3) in the Rebind message. Section 21.3) in the Rebind message.
The client transmits the message according to Section 15, using the The client transmits the message according to Section 15, using the
following parameters: following parameters:
IRT REB_TIMEOUT * IRT: REB_TIMEOUT
MRT REB_MAX_RT
MRC 0 * MRT: REB_MAX_RT
MRD Remaining time until valid lifetimes of all leases in all * MRC: 0
IAs have expired
* MRD: Remaining time until valid lifetimes of all leases in all IAs
have expired
If all leases for an IA have expired, the client may choose to If all leases for an IA have expired, the client may choose to
include this IA in subsequent Rebind messages to indicate that the include this IA in subsequent Rebind messages to indicate that the
client is interested in assignment of the leases to this IA. client is interested in assignment of the leases to this IA.
The message exchange is terminated when the valid lifetimes of all The message exchange is terminated when the valid lifetimes of all
leases across all IAs have expired, at which time the client uses the leases across all IAs have expired, at which time the client uses the
Solicit message to locate a new DHCP server and sends a Request for Solicit message to locate a new DHCP server and sends a Request for
the expired IAs to the new server. If the terminated Rebind exchange the expired IAs to the new server. If the terminated Rebind exchange
was initiated as a result of receiving a Reconfigure message, the was initiated as a result of receiving a Reconfigure message, the
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delegated prefixes to be assigned. delegated prefixes to be assigned.
The client sets the "msg-type" field to INFORMATION-REQUEST. The The client sets the "msg-type" field to INFORMATION-REQUEST. The
client generates a transaction ID and inserts this value in the client generates a transaction ID and inserts this value in the
"transaction-id" field. "transaction-id" field.
The client SHOULD include a Client Identifier option (see The client SHOULD include a Client Identifier option (see
Section 21.2) to identify itself to the server (however, see Section 21.2) to identify itself to the server (however, see
Section 4.3.1 of [RFC7844] for reasons why a client may not want to Section 4.3.1 of [RFC7844] for reasons why a client may not want to
include this option). If the client does not include a Client include this option). If the client does not include a Client
Identifier option, the server will not be able to return any Identifier option, the server will not be able to return any client-
client-specific options to the client, or the server may choose not specific options to the client, or the server may choose not to
to respond to the message at all. respond to the message at all.
The client MUST include an Elapsed Time option (see Section 21.9) to The client MUST include an Elapsed Time option (see Section 21.9) to
indicate how long the client has been trying to complete the current indicate how long the client has been trying to complete the current
DHCP message exchange. DHCP message exchange.
The client MUST include an Option Request option (see Section 21.7) The client MUST include an Option Request option (see Section 21.7)
to request the INF_MAX_RT option (see Section 21.25), the Information to request the INF_MAX_RT option (see Section 21.25), the Information
Refresh Time option (see Section 21.23), and any other options the Refresh Time option (see Section 21.23), and any other options the
client is interested in receiving. The client MAY include options client is interested in receiving. The client MAY include options
with data values as hints to the server about parameter values the with data values as hints to the server about parameter values the
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When responding to a Reconfigure, the client MUST include a Server When responding to a Reconfigure, the client MUST include a Server
Identifier option (see Section 21.3) with the identifier from the Identifier option (see Section 21.3) with the identifier from the
Reconfigure message to which the client is responding. Reconfigure message to which the client is responding.
The first Information-request message from the client on the The first Information-request message from the client on the
interface MUST be delayed by a random amount of time between 0 and interface MUST be delayed by a random amount of time between 0 and
INF_MAX_DELAY. The client transmits the message according to INF_MAX_DELAY. The client transmits the message according to
Section 15, using the following parameters: Section 15, using the following parameters:
IRT INF_TIMEOUT * IRT: INF_TIMEOUT
MRT INF_MAX_RT * MRT: INF_MAX_RT
MRC 0 * MRC: 0
MRD 0 * MRD: 0
18.2.7. Creation and Transmission of Release Messages 18.2.7. Creation and Transmission of Release Messages
To release one or more leases, a client sends a Release message to To release one or more leases, a client sends a Release message to
the server. the server.
The client sets the "msg-type" field to RELEASE. The client The client sets the "msg-type" field to RELEASE. The client
generates a transaction ID and places this value in the generates a transaction ID and places this value in the "transaction-
"transaction-id" field. id" field.
The client MUST include a Server Identifier option (see Section 21.3) The client MUST include a Server Identifier option (see Section 21.3)
in the Renew message, identifying the server which allocated the in the Renew message, identifying the server that allocated the
lease(s). lease(s).
The client MUST include a Client Identifier option (see Section 21.2) The client MUST include a Client Identifier option (see Section 21.2)
to identify itself to the server. to identify itself to the server.
The client MUST include an Elapsed Time option (see Section 21.9) to The client MUST include an Elapsed Time option (see Section 21.9) to
indicate how long the client has been trying to complete the current indicate how long the client has been trying to complete the current
DHCP message exchange. DHCP message exchange.
The client includes options containing the IAs for the leases it is The client includes options containing the IAs for the leases it is
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Because Release messages may be lost, the client should retransmit Because Release messages may be lost, the client should retransmit
the Release if no Reply is received. However, there are scenarios the Release if no Reply is received. However, there are scenarios
where the client may not wish to wait for the normal retransmission where the client may not wish to wait for the normal retransmission
timeout before giving up (e.g., on power down). Implementations timeout before giving up (e.g., on power down). Implementations
SHOULD retransmit one or more times but MAY choose to terminate the SHOULD retransmit one or more times but MAY choose to terminate the
retransmission procedure early. retransmission procedure early.
The client transmits the message according to Section 15, using the The client transmits the message according to Section 15, using the
following parameters: following parameters:
IRT REL_TIMEOUT * IRT: REL_TIMEOUT
MRT 0 * MRT: 0
MRC REL_MAX_RC * MRC: REL_MAX_RC
MRD 0 * MRD: 0
If leases are released but the Reply from a DHCP server is lost, the If leases are released but the Reply from a DHCP server is lost, the
client will retransmit the Release message, and the server may client will retransmit the Release message, and the server may
respond with a Reply indicating a status of NoBinding. Therefore, respond with a Reply indicating a status of NoBinding. Therefore,
the client does not treat a Reply message with a status of NoBinding the client does not treat a Reply message with a status of NoBinding
in a Release message exchange as if it indicates an error. in a Release message exchange as if it indicates an error.
Note that if the client fails to release the lease, each lease Note that if the client fails to release the lease, each lease
assigned to the IA will be reclaimed by the server when the valid assigned to the IA will be reclaimed by the server when the valid
lifetime of that lease expires. lifetime of that lease expires.
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If a client detects that one or more addresses assigned to it by a If a client detects that one or more addresses assigned to it by a
server are already in use by another node, the client sends a Decline server are already in use by another node, the client sends a Decline
message to the server to inform it that the address is suspect. message to the server to inform it that the address is suspect.
The Decline message is not used in prefix delegation; thus, the The Decline message is not used in prefix delegation; thus, the
client MUST NOT include IA_PD options (see Section 21.21) in the client MUST NOT include IA_PD options (see Section 21.21) in the
Decline message. Decline message.
The client sets the "msg-type" field to DECLINE. The client The client sets the "msg-type" field to DECLINE. The client
generates a transaction ID and places this value in the generates a transaction ID and places this value in the "transaction-
"transaction-id" field. id" field.
The client MUST include a Server Identifier option (see Section 21.3) The client MUST include a Server Identifier option (see Section 21.3)
in the Decline message, identifying the server which allocated the in the Decline message, identifying the server that allocated the
lease(s). lease(s).
The client MUST include a Client Identifier option (see Section 21.2) The client MUST include a Client Identifier option (see Section 21.2)
to identify itself to the server. to identify itself to the server.
The client MUST include an Elapsed Time option (see Section 21.9) to The client MUST include an Elapsed Time option (see Section 21.9) to
indicate how long the client has been trying to complete the current indicate how long the client has been trying to complete the current
DHCP message exchange. DHCP message exchange.
The client includes options containing the IAs for the addresses it The client includes options containing the IAs for the addresses it
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MUST be included in the IAs. Any addresses for the IAs the client MUST be included in the IAs. Any addresses for the IAs the client
wishes to continue to use should not be added to the IAs. wishes to continue to use should not be added to the IAs.
The client MUST NOT use any of the addresses it is declining as the The client MUST NOT use any of the addresses it is declining as the
source address in the Decline message or in any subsequently source address in the Decline message or in any subsequently
transmitted message. transmitted message.
The client transmits the message according to Section 15, using the The client transmits the message according to Section 15, using the
following parameters: following parameters:
IRT DEC_TIMEOUT * IRT: DEC_TIMEOUT
MRT 0 * MRT: 0
MRC DEC_MAX_RC * MRC: DEC_MAX_RC
MRD 0 * MRD: 0
If addresses are declined but the Reply from a DHCP server is lost, If addresses are declined but the Reply from a DHCP server is lost,
the client will retransmit the Decline message, and the server may the client will retransmit the Decline message, and the server may
respond with a Reply indicating a status of NoBinding. Therefore, respond with a Reply indicating a status of NoBinding. Therefore,
the client does not treat a Reply message with a status of NoBinding the client does not treat a Reply message with a status of NoBinding
in a Decline message exchange as if it indicates an error. in a Decline message exchange as if it indicates an error.
The client SHOULD NOT send a Release message for other bindings it The client SHOULD NOT send a Release message for other bindings it
may have received just because it sent a Decline message. The client may have received just because it sent a Decline message. The client
SHOULD retain the non-conflicting bindings. The client SHOULD treat SHOULD retain the non-conflicting bindings. The client SHOULD treat
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option is not present in the Reply, the client SHOULD stop using the option is not present in the Reply, the client SHOULD stop using the
previously received configuration information. In other words, the previously received configuration information. In other words, the
client should behave as if it never received this configuration client should behave as if it never received this configuration
option and return to the relevant default state. If there is no option and return to the relevant default state. If there is no
viable way to stop using the received configuration information, the viable way to stop using the received configuration information, the
values received/configured from the option MAY persist if there are values received/configured from the option MAY persist if there are
no other sources for that data and they have no external impact. For no other sources for that data and they have no external impact. For
example, a client that previously received a Client FQDN option (see example, a client that previously received a Client FQDN option (see
[RFC4704]) and used it to set up its hostname is allowed to continue [RFC4704]) and used it to set up its hostname is allowed to continue
using it if there is no reasonable way for a node to unset its using it if there is no reasonable way for a node to unset its
hostname and it has no external impact. As a counter-example, a hostname and it has no external impact. As a counterexample, a
client that previously received an NTP server address from the DHCP client that previously received an NTP server address from the DHCP
server and does not receive it anymore MUST stop using the configured server and does not receive it anymore MUST stop using the configured
NTP server address. The client SHOULD be open to other sources of NTP server address. The client SHOULD be open to other sources of
the same configuration information. This behavior does not apply to the same configuration information. This behavior does not apply to
any IA options, as their processing is described in Section 18.2.10.1 any IA options; their processing is described in Section 18.2.10.1.
18.2.11. Receipt of Reconfigure Messages 18.2.11. Receipt of Reconfigure Messages
A client receives Reconfigure messages sent to UDP port 546 on A client receives Reconfigure messages sent to UDP port 546 on
interfaces for which it has acquired configuration information interfaces for which it has acquired configuration information
through DHCP. These messages may be sent at any time. Since the through DHCP. These messages may be sent at any time. Since the
results of a reconfiguration event may affect application-layer results of a reconfiguration event may affect application-layer
programs, the client SHOULD log these events and MAY notify these programs, the client SHOULD log these events and MAY notify these
programs of the change through an implementation-specific interface. programs of the change through an implementation-specific interface.
The message MUST be dropped if it doesn't pass the validation, as The message MUST be dropped if it doesn't pass the validation, as
explained in (see Section 16.11), in particular in case the explained in Section 16.11, particularly in cases where the
authentication is missing or fails. authentication is missing or fails.
Upon receipt of a valid Reconfigure message, the client responds with Upon receipt of a valid Reconfigure message, the client responds with
a Renew message, a Rebind message, or an Information-request message a Renew message, a Rebind message, or an Information-request message
as indicated by the Reconfigure Message option (see Section 21.19). as indicated by the Reconfigure Message option (see Section 21.19).
The client ignores the "transaction-id" field in the received The client ignores the "transaction-id" field in the received
Reconfigure message. While the transaction is in progress, the Reconfigure message. While the transaction is in progress, the
client discards any Reconfigure messages it receives. client discards any Reconfigure messages it receives.
The Reconfigure message acts as a trigger that signals the client to The Reconfigure message acts as a trigger that signals the client to
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a Reconfigure, the client proceeds with the message exchange a Reconfigure, the client proceeds with the message exchange
(retransmitting the Renew, Rebind, or Information-request message if (retransmitting the Renew, Rebind, or Information-request message if
necessary); the client MUST ignore any additional Reconfigure necessary); the client MUST ignore any additional Reconfigure
messages until the exchange is complete. messages until the exchange is complete.
Duplicate messages will be ignored because the client will begin the Duplicate messages will be ignored because the client will begin the
exchange after the receipt of the first Reconfigure. Retransmitted exchange after the receipt of the first Reconfigure. Retransmitted
messages will either (1) trigger the exchange (if the first messages will either (1) trigger the exchange (if the first
Reconfigure was not received by the client) or (2) be ignored. The Reconfigure was not received by the client) or (2) be ignored. The
server MAY discontinue retransmission of Reconfigure messages to the server MAY discontinue retransmission of Reconfigure messages to the
client once the server receives the Renew, Rebind, or client once the server receives the Renew, Rebind, or Information-
Information-request message from the client. request message from the client.
It might be possible for a duplicate or retransmitted Reconfigure to It might be possible for a duplicate or retransmitted Reconfigure to
be sufficiently delayed (and delivered out of order) that it arrives be sufficiently delayed (and delivered out of order) that it arrives
at the client after the exchange (initiated by the original at the client after the exchange (initiated by the original
Reconfigure) has been completed. In this case, the client would Reconfigure) has been completed. In this case, the client would
initiate a redundant exchange. The likelihood of delayed and initiate a redundant exchange. The likelihood of delayed and out-of-
out-of-order delivery is small enough to be ignored. The consequence order delivery is small enough to be ignored. The consequence of the
of the redundant exchange is inefficiency rather than incorrect redundant exchange is inefficiency rather than incorrect operation.
operation.
18.2.12. Refreshing Configuration Information 18.2.12. Refreshing Configuration Information
Whenever a client may have moved to a new link, the Whenever a client may have moved to a new link, the prefixes/
prefixes/addresses assigned to the interfaces on that link may no addresses assigned to the interfaces on that link may no longer be
longer be appropriate for the link to which the client is attached. appropriate for the link to which the client is attached. Examples
Examples of times when a client may have moved to a new link include of times when a client may have moved to a new link include the
the following: following:
* The client reboots (and has stable storage and persistent DHCP * The client reboots (and has stable storage and persistent DHCP
state). state).
* The client is reconnected to a link on which it has obtained * The client is reconnected to a link on which it has obtained
leases. leases.
* The client returns from sleep mode. * The client returns from sleep mode.
* The client changes access points (e.g., if using Wi-Fi * The client changes access points (e.g., if using Wi-Fi
technology). technology).
* The client's network interface indicates a disconnection event, * The client's network interface indicates a disconnection event
followed by a connection event. followed by a connection event.
Specific algorithms for detecting network attachment changes are out Specific algorithms for detecting network attachment changes are out
of scope for this document. Two possible mechanisms for detecting of scope for this document. Two possible mechanisms for detecting
situations where refreshing configuration information may be needed situations where refreshing configuration information may be needed
are defined in [RFC6059] and [RFC4957]. are defined in [RFC6059] and [RFC4957].
When the client detects that it may have moved to a new link and it When the client detects that it may have moved to a new link and it
has obtained addresses and no delegated prefixes from a server, the has obtained addresses and no delegated prefixes from a server, the
client SHOULD initiate a Confirm/Reply message exchange. The client client SHOULD initiate a Confirm/Reply message exchange. The client
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with requests when there are link issues (for example, only doing one with requests when there are link issues (for example, only doing one
of these at most every 30 seconds). of these at most every 30 seconds).
The above selection of an exchange to initiate depends on the The above selection of an exchange to initiate depends on the
client's current state: client's current state:
* If the client has any valid delegated prefixes obtained from the * If the client has any valid delegated prefixes obtained from the
server, it sends Renew (as if the T1 time expired) as described in server, it sends Renew (as if the T1 time expired) as described in
Section 18.2.4. Section 18.2.4.
* Else, if the client obtained address(es) from the server, it sends * Else, if the client obtained an address(es) from the server, it
Confirm as described in Section 18.2.3. sends Confirm as described in Section 18.2.3.
* Else, if only network information was obtained from the server, it * Else, if only network information was obtained from the server, it
sends Information-request as described in Section 18.2.6 sends an Information-request as described in Section 18.2.6.
18.2.13. Restarting Server Discovery Process 18.2.13. Restarting Server Discovery Process
Whenever a client restarts the DHCP server discovery process or Whenever a client restarts the DHCP server discovery process or
selects an alternate server as described in Section 18.2.9, the selects an alternate server as described in Section 18.2.9, the
client SHOULD stop using any addresses and delegated prefixes for client SHOULD stop using any addresses and delegated prefixes for
which it has bindings (see Section 18.2.7) and if possible, any which it has bindings (see Section 18.2.7) and, if possible, any
previously received other configuration information, and try to other configuration information it previously received. The client
obtain new bindings and other configuration information from a "new" SHOULD also try to obtain new bindings and other configuration
server for the same interface. This facilitates the client using a information from a "new" server for the same interface. This
single state machine for all bindings. facilitates the client using a single state machine for all bindings.
18.3. Server Behavior 18.3. Server Behavior
For this discussion, the server is assumed to have been configured in For this discussion, the server is assumed to have been configured in
an implementation-specific manner with configurations of interest to an implementation-specific manner with configurations of interest to
clients. clients.
A server sends an Advertise message in response to each valid Solicit A server sends an Advertise message in response to each valid Solicit
message it receives to announce the availability of the server to the message it receives to announce the availability of the server to the
client. client.
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as though it had received a Request message as described in as though it had received a Request message as described in
Section 18.3.2. The server transmits the Reply message as described Section 18.3.2. The server transmits the Reply message as described
in Section 18.3.10. The server MUST commit the assignment of any in Section 18.3.10. The server MUST commit the assignment of any
addresses and delegated prefixes or other configuration information addresses and delegated prefixes or other configuration information
before sending a Reply message to a client. In this case, the server before sending a Reply message to a client. In this case, the server
includes a Rapid Commit option in the Reply message to indicate that includes a Rapid Commit option in the Reply message to indicate that
the Reply is in response to a Solicit message. the Reply is in response to a Solicit message.
DISCUSSION: DISCUSSION:
When using the Solicit/Reply message exchange, the server commits * When using the Solicit/Reply message exchange, the server commits
the assignment of any leases before sending the Reply message. the assignment of any leases before sending the Reply message.
The client can assume that it has been assigned the leases in the The client can assume that it has been assigned the leases in the
Reply message and does not need to send a Request message for Reply message and does not need to send a Request message for
those leases. those leases.
Typically, servers that are configured to use the Solicit/Reply * Typically, servers that are configured to use the Solicit/Reply
message exchange will be deployed so that only one server will message exchange will be deployed so that only one server will
respond to a Solicit message. If more than one server responds, respond to a Solicit message. If more than one server responds,
the client will only use the leases from one of the servers, while the client will only use the leases from one of the servers, while
the leases from the other servers will be committed to the client the leases from the other servers will be committed to the client
but not used by the client. but not used by the client.
18.3.2. Receipt of Request Messages 18.3.2. Receipt of Request Messages
When the server receives a valid Request message, the server creates When the server receives a valid Request message, the server creates
the bindings for that client according to the server's policy and the bindings for that client according to the server's policy and
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the IA with the client, the server sends a Reply message with the IA with the client, the server sends a Reply message with
existing bindings, possibly with updated lifetimes. The server may existing bindings, possibly with updated lifetimes. The server may
update the bindings according to its local policies, but the server update the bindings according to its local policies, but the server
SHOULD generate the response again and not simply retransmit SHOULD generate the response again and not simply retransmit
previously sent information, even if the "transaction-id" field value previously sent information, even if the "transaction-id" field value
matches a previous transmission. The server MUST NOT cache its matches a previous transmission. The server MUST NOT cache its
responses. responses.
DISCUSSION: DISCUSSION:
Cached replies are bad because lifetimes need to be updated * Cached replies are bad because lifetimes need to be updated
(either decrease the timers by the amount of time elapsed since (either decrease the timers by the amount of time elapsed since
the original transmission or keep the lifetime values and update the original transmission or keep the lifetime values and update
the lease information in the server's database). Also, if the the lease information in the server's database). Also, if the
message uses any security protection (such as the Replay Detection message uses any security protection (such as the Replay Detection
Method (RDM), as described in Section 20.3), its value must be Method (RDM), as described in Section 20.3), its value must be
updated. Additionally, any digests must be updated. Given all of updated. Additionally, any digests must be updated. Given all of
the above, caching replies is far more complex than simply sending the above, caching replies is far more complex than simply sending
the same buffer as before, and it is easy to miss some of those the same buffer as before, and it is easy to miss some of those
steps. steps.
18.3.3. Receipt of Confirm Messages 18.3.3. Receipt of Confirm Messages
When the server receives a Confirm message, the server determines When the server receives a Confirm message, the server determines
whether the addresses in the Confirm message are appropriate for the whether the addresses in the Confirm message are appropriate for the
link to which the client is attached. If all of the addresses in the link to which the client is attached. If all of the addresses in the
Confirm message pass this test, the server returns a status of Confirm message pass this test, the server returns a status of
Success. If any of the addresses do not pass this test, the server Success. If any of the addresses do not pass this test, the server
returns a status of NotOnLink. If the server is unable to perform returns a status of NotOnLink. If the server is unable to perform
this test (for example, the server does not have information about this test (for example, the server does not have information about
prefixes on the link to which the client is connected) or there were prefixes on the link to which the client is connected) or there were
no addresses in any of the IAs sent by the client, the server no addresses in any of the IAs sent by the client, the server MUST
MUST NOT send a Reply to the client. NOT send a Reply to the client.
The server ignores the T1 and T2 fields in the IA options and the The server ignores the T1 and T2 fields in the IA options and the
preferred-lifetime and valid-lifetime fields in the IA Address preferred-lifetime and valid-lifetime fields in the IA Address
options (see Section 21.6). options (see Section 21.6).
The server constructs a Reply message by setting the "msg-type" field The server constructs a Reply message by setting the "msg-type" field
to REPLY and copying the transaction ID from the Confirm message into to REPLY and copying the transaction ID from the Confirm message into
the "transaction-id" field. the "transaction-id" field.
The server MUST include in the Reply message a Server Identifier The server MUST include in the Reply message a Server Identifier
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The server may choose to change the list of addresses or delegated The server may choose to change the list of addresses or delegated
prefixes and the lifetimes in IAs that are returned to the client. prefixes and the lifetimes in IAs that are returned to the client.
If the server finds that any of the addresses in the IA are not If the server finds that any of the addresses in the IA are not
appropriate for the link to which the client is attached, the server appropriate for the link to which the client is attached, the server
returns the address to the client with lifetimes of 0. returns the address to the client with lifetimes of 0.
If the server finds that any of the delegated prefixes in the IA are If the server finds that any of the delegated prefixes in the IA are
not appropriate for the link to which the client is attached, the not appropriate for the link to which the client is attached, the
server returns the delegated prefix to the client with lifetimes server returns the delegated prefix to the client with lifetimes of
of 0. 0.
For each IA for which the server cannot find a client entry, the For each IA for which the server cannot find a client entry, the
server has the following choices, depending on the server's policy server has the following choices, depending on the server's policy
and configuration information: and configuration information:
* If the server is configured to create new bindings as a result of * If the server is configured to create new bindings as a result of
processing Renew messages, the server SHOULD create a binding and processing Renew messages, the server SHOULD create a binding and
return the IA with assigned addresses or delegated prefixes with return the IA with assigned addresses or delegated prefixes with
lifetimes and, if applicable, T1/T2 times and other information lifetimes and, if applicable, T1/T2 times and other information
requested by the client. If the client included the IA Prefix requested by the client. If the client included the IA Prefix
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The server includes options containing configuration information to The server includes options containing configuration information to
be returned to the client as described in Section 18.3. The server be returned to the client as described in Section 18.3. The server
MAY include additional options that were not requested by the client MAY include additional options that were not requested by the client
in the Information-request message. in the Information-request message.
If the Information-request message received from the client did not If the Information-request message received from the client did not
include a Client Identifier option, the server SHOULD respond with a include a Client Identifier option, the server SHOULD respond with a
Reply message containing any configuration parameters that are not Reply message containing any configuration parameters that are not
determined by the client's identity. If the server chooses not to determined by the client's identity. If the server chooses not to
respond, the client may continue to retransmit the respond, the client may continue to retransmit the Information-
Information-request message indefinitely. request message indefinitely.
18.3.7. Receipt of Release Messages 18.3.7. Receipt of Release Messages
The server constructs a Reply message by setting the "msg-type" field The server constructs a Reply message by setting the "msg-type" field
to REPLY and copying the transaction ID from the Release message into to REPLY and copying the transaction ID from the Release message into
the "transaction-id" field. the "transaction-id" field.
Upon the receipt of a valid Release message, the server examines the Upon the receipt of a valid Release message, the server examines the
IAs and the leases in the IAs for validity. If the IAs in the IAs and the leases in the IAs for validity. If the IAs in the
message are in a binding for the client and the leases in the IAs message are in a binding for the client and the leases in the IAs
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If the original message was received directly by the server, the If the original message was received directly by the server, the
server unicasts the Advertise or Reply message directly to the client server unicasts the Advertise or Reply message directly to the client
using the address in the source address field from the IP datagram in using the address in the source address field from the IP datagram in
which the original message was received. The Advertise or Reply which the original message was received. The Advertise or Reply
message MUST be unicast through the interface on which the original message MUST be unicast through the interface on which the original
message was received. message was received.
If the original message was received in a Relay-forward message, the If the original message was received in a Relay-forward message, the
server constructs a Relay-reply message with the Reply message in the server constructs a Relay-reply message with the Reply message in the
payload of a Relay Message option (see Section 21.10). If the payload of a Relay Message option (see Section 21.10). If the Relay-
Relay-forward messages included an Interface-Id option (see forward messages included an Interface-Id option (see Section 21.18),
Section 21.18), the server copies that option to the Relay-reply the server copies that option to the Relay-reply message. The server
message. The server unicasts the Relay-reply message directly to the unicasts the Relay-reply message directly to the relay agent using
relay agent using the address in the source address field from the IP the address in the source address field from the IP datagram in which
datagram in which the Relay-forward message was received. See the Relay-forward message was received. See Section 19.3 for more
Section 19.3 for more details on the construction of Relay-reply details on the construction of Relay-reply messages.
messages.
18.3.11. Creation and Transmission of Reconfigure Messages 18.3.11. Creation and Transmission of Reconfigure Messages
The server sets the "msg-type" field to RECONFIGURE and sets the The server sets the "msg-type" field to RECONFIGURE and sets the
"transaction-id" field to 0. The server includes a Server Identifier "transaction-id" field to 0. The server includes a Server Identifier
option (see Section 21.3) containing its DUID and a Client Identifier option (see Section 21.3) containing its DUID and a Client Identifier
option (see Section 21.2) containing the client's DUID in the option (see Section 21.2) containing the client's DUID in the
Reconfigure message. Reconfigure message.
Because of the risk of denial-of-service (DoS) attacks against DHCP Because of the risk of denial-of-service (DoS) attacks against DHCP
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19. Relay Agent Behavior 19. Relay Agent Behavior
The relay agent SHOULD be configured to use a list of destination The relay agent SHOULD be configured to use a list of destination
addresses that includes unicast addresses. The list of destination addresses that includes unicast addresses. The list of destination
addresses MAY include the All_DHCP_Servers multicast address or other addresses MAY include the All_DHCP_Servers multicast address or other
addresses selected by the network administrator. If the relay agent addresses selected by the network administrator. If the relay agent
has not been explicitly configured, it MUST use the All_DHCP_Servers has not been explicitly configured, it MUST use the All_DHCP_Servers
multicast address as the default. multicast address as the default.
If the relay agent relays messages to the All_DHCP_Servers multicast If the relay agent relays messages to the All_DHCP_Servers multicast
address or other multicast addresses, it sets the Hop Limit field address or other multicast addresses, it sets the Hop Limit field to
to 8. 8.
If the relay agent receives a message other than Relay-forward and If the relay agent receives a message other than Relay-forward and
Relay-reply and the relay agent does not recognize its message type, Relay-reply and the relay agent does not recognize its message type,
it MUST forward the message as described in Section 19.1.1. it MUST forward the message as described in Section 19.1.1.
19.1. Relaying a Client Message or a Relay-forward Message 19.1. Relaying a Client Message or a Relay-forward Message
A relay agent relays both messages from clients and Relay-forward A relay agent relays both messages from clients and Relay-forward
messages from other relay agents. When a relay agent receives a messages from other relay agents. When a relay agent receives a
Relay-forward message, a recognized message type for which it is not Relay-forward message, a recognized message type for which it is not
skipping to change at page 85, line 28 skipping to change at line 3937
relay agent sets the link-address field to 0; otherwise, the relay relay agent sets the link-address field to 0; otherwise, the relay
agent sets the link-address field to a globally scoped unicast agent sets the link-address field to a globally scoped unicast
address (i.e., GUA or ULA) assigned to the interface on which the address (i.e., GUA or ULA) assigned to the interface on which the
message was received or includes an Interface-Id option (see message was received or includes an Interface-Id option (see
Section 21.18) to identify the interface on which the message was Section 21.18) to identify the interface on which the message was
received. received.
19.1.3. Relay Agent Behavior with Prefix Delegation 19.1.3. Relay Agent Behavior with Prefix Delegation
A relay agent forwards messages containing prefix delegation options A relay agent forwards messages containing prefix delegation options
in the same way as it would relay addresses (i.e., per in the same way as it would relay addresses (i.e., per Sections
Sections 19.1.1 and 19.1.2). 19.1.1 and 19.1.2).
If a server communicates with a client through a relay agent about If a server communicates with a client through a relay agent about
delegated prefixes, the server may need a protocol or other delegated prefixes, the server may need a protocol or other out-of-
out-of-band communication to configure routing information for band communication to configure routing information for delegated
delegated prefixes on any router through which the client may forward prefixes on any router through which the client may forward traffic.
traffic.
19.2. Relaying a Relay-reply Message 19.2. Relaying a Relay-reply Message
The relay agent processes any options included in the Relay-reply The relay agent processes any options included in the Relay-reply
message in addition to the Relay Message option (see Section 21.10). message in addition to the Relay Message option (see Section 21.10).
The relay agent extracts the message from the Relay Message option The relay agent extracts the message from the Relay Message option
and relays it to the address contained in the peer-address field of and relays it to the address contained in the peer-address field of
the Relay-reply message. Relay agents MUST NOT modify the message. the Relay-reply message. Relay agents MUST NOT modify the message.
skipping to change at page 87, line 8 skipping to change at line 4003
hop-count: 0 hop-count: 0
link-address: address from link to which C is attached link-address: address from link to which C is attached
peer-address: C peer-address: C
Relay Message option: <response from server> Relay Message option: <response from server>
Figure 10: Relay-reply Example Figure 10: Relay-reply Example
When sending a Reconfigure message to a client through a relay agent, When sending a Reconfigure message to a client through a relay agent,
the server creates a Relay-reply message that includes a Relay the server creates a Relay-reply message that includes a Relay
Message option containing the Reconfigure message for the next relay Message option containing the Reconfigure message for the next relay
agent in the return path to the client. The server sets the agent in the return path to the client. The server sets the peer-
peer-address field in the Relay-reply message header to the address address field in the Relay-reply message header to the address of the
of the client and sets the link-address field as required by the client and sets the link-address field as required by the relay agent
relay agent to relay the Reconfigure message to the client. The to relay the Reconfigure message to the client. The server obtains
server obtains the addresses of the client and the relay agent the addresses of the client and the relay agent through prior
through prior interaction with the client or through some external interaction with the client or through some external mechanism.
mechanism.
19.4. Interaction between Relay Agents and Servers 19.4. Interaction Between Relay Agents and Servers
Each time a message is relayed by a relay agent towards a server, a Each time a message is relayed by a relay agent towards a server, a
new encapsulation level is added around the message. Each relay is new encapsulation level is added around the message. Each relay is
allowed to insert additional options on the encapsulation level it allowed to insert additional options on the encapsulation level it
added but MUST NOT change anything in the message being encapsulated. added but MUST NOT change anything in the message being encapsulated.
If there are multiple relays between a client and a server, multiple If there are multiple relays between a client and a server, multiple
encapsulations are used. Although it makes message processing encapsulations are used. Although it makes message processing
slightly more complex, it provides the major advantage of having a slightly more complex, it provides the major advantage of having a
clear indication as to which relay inserted which option. The clear indication as to which relay inserted which option. The
response message is expected to travel through the same relays, but response message is expected to travel through the same relays, but
skipping to change at page 88, line 22 skipping to change at line 4065
assigned via a specific relay. A second is for the reconfigure assigned via a specific relay. A second is for the reconfigure
mechanism. The server may choose to not send the Reconfigure message mechanism. The server may choose to not send the Reconfigure message
directly to the client but rather to send it via relays. This directly to the client but rather to send it via relays. This
particular behavior is considered an implementation detail and is out particular behavior is considered an implementation detail and is out
of scope for this document. of scope for this document.
20. Authentication of DHCP Messages 20. Authentication of DHCP Messages
This document introduces two security mechanisms for the This document introduces two security mechanisms for the
authentication of DHCP messages: (1) authentication (and encryption) authentication of DHCP messages: (1) authentication (and encryption)
of messages sent between servers and relay agents using IPsec and of messages sent between servers and relay agents using IPsec and (2)
(2) protection against misconfiguration of a client caused by a protection against misconfiguration of a client caused by a
Reconfigure message sent by a malicious DHCP server. Reconfigure message sent by a malicious DHCP server.
20.1. Security of Messages Sent between Servers and Relay Agents 20.1. Security of Messages Sent Between Servers and Relay Agents
Relay agents and servers that exchange messages can use IPsec as Relay agents and servers that exchange messages can use IPsec as
detailed in [RFC8213]. detailed in [RFC8213].
20.2. Summary of DHCP Authentication 20.2. Summary of DHCP Authentication
Authentication of DHCP messages is accomplished through the use of Authentication of DHCP messages is accomplished through the use of
the Authentication option (see Section 21.11). The authentication the Authentication option (see Section 21.11). The authentication
information carried in the Authentication option can be used to information carried in the Authentication option can be used to
reliably identify the source of a DHCP message and to confirm that reliably identify the source of a DHCP message and to confirm that
skipping to change at page 90, line 13 skipping to change at line 4151
defined in the following section. defined in the following section.
RKAP is used (initiated by the server) only if the client and server RKAP is used (initiated by the server) only if the client and server
have negotiated to use Reconfigure messages. have negotiated to use Reconfigure messages.
20.4.1. Use of the Authentication Option in RKAP 20.4.1. Use of the Authentication Option in RKAP
The following fields are set in an Authentication option (see The following fields are set in an Authentication option (see
Section 21.11) for RKAP: Section 21.11) for RKAP:
protocol 3 * protocol: 3
algorithm 1 * algorithm: 1
RDM 0 * RDM: 0
The format of the authentication information for RKAP is: The format of the authentication information for RKAP is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Value (128 bits) | | Type | Value (128 bits) |
+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+ |
. . . .
. . . .
. +-+-+-+-+-+-+-+-+ . +-+-+-+-+-+-+-+-+
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: RKAP Authentication Information Figure 11: RKAP Authentication Information
Type Type of data in the Value field carried in this Type: Type of data in the Value field carried in this option:
option:
1 Reconfigure key value (used in the Reply 1 Reconfigure key value (used in the Reply message).
message).
2 HMAC-MD5 digest of the message (used in 2 HMAC-MD5 digest of the message (used in the Reconfigure
the Reconfigure message). message).
A 1-octet field. A 1-octet field.
Value Data as defined by the Type field. A 16-octet Value: Data as defined by the Type field. A 16-octet field.
field.
20.4.2. Server Considerations for RKAP 20.4.2. Server Considerations for RKAP
The server selects a reconfigure key for a client during the The server selects a reconfigure key for a client during the Request/
Request/Reply, Solicit/Reply, or Information-request/Reply message Reply, Solicit/Reply, or Information-request/Reply message exchange.
exchange. The server records the reconfigure key and transmits that The server records the reconfigure key and transmits that key to the
key to the client in an Authentication option (see Section 21.11) in client in an Authentication option (see Section 21.11) in the Reply
the Reply message. message.
The reconfigure key is 128 bits long and MUST be a cryptographically The reconfigure key is 128 bits long and MUST be a cryptographically
strong random or pseudorandom number that cannot easily be predicted. strong random or pseudorandom number that cannot easily be predicted.
To provide authentication for a Reconfigure message, the server To provide authentication for a Reconfigure message, the server
selects a replay detection value according to the RDM selected by the selects a replay detection value according to the RDM selected by the
server and computes an HMAC-MD5 of the Reconfigure message using the server and computes an HMAC-MD5 of the Reconfigure message using the
reconfigure key for the client. The server computes the HMAC-MD5 reconfigure key for the client. The server computes the HMAC-MD5
over the entire DHCP Reconfigure message, including the over the entire DHCP Reconfigure message, including the
Authentication option; the HMAC-MD5 field in the Authentication Authentication option; the HMAC-MD5 field in the Authentication
skipping to change at page 91, line 34 skipping to change at line 4212
Authentication option included in the Reconfigure message sent to the Authentication option included in the Reconfigure message sent to the
client. client.
20.4.3. Client Considerations for RKAP 20.4.3. Client Considerations for RKAP
The client will receive a reconfigure key from the server in an The client will receive a reconfigure key from the server in an
Authentication option (see Section 21.11) in the initial Reply Authentication option (see Section 21.11) in the initial Reply
message from the server. The client records the reconfigure key for message from the server. The client records the reconfigure key for
use in authenticating subsequent Reconfigure messages. use in authenticating subsequent Reconfigure messages.
To authenticate a Reconfigure message, the client computes an To authenticate a Reconfigure message, the client computes an HMAC-
HMAC-MD5 over the Reconfigure message, with zeroes substituted for MD5 over the Reconfigure message, with zeroes substituted for the
the HMAC-MD5 field, using the reconfigure key received from the HMAC-MD5 field, using the reconfigure key received from the server.
server. If this computed HMAC-MD5 matches the value in the If this computed HMAC-MD5 matches the value in the Authentication
Authentication option, the client accepts the Reconfigure message. option, the client accepts the Reconfigure message.
21. DHCP Options 21. DHCP Options
Options are used to carry additional information and parameters in Options are used to carry additional information and parameters in
DHCP messages. Every option shares a common base format, as DHCP messages. Every option shares a common base format, as
described in Section 21.1. All values in options are represented in described in Section 21.1. All values in options are represented in
network byte order. network byte order.
This document specifies the DHCP options defined as part of this base This document specifies the DHCP options defined as part of this base
DHCP specification. Other options have been or may be defined in the DHCP specification. Other options have been or may be defined in the
future in separate documents. See [RFC7227] for guidelines regarding future in separate documents. See [RFC7227] for guidelines regarding
the definition of new options. See Section 25 for additional the definition of new options. See Section 24 for additional
information about the DHCPv6 "Option Codes" registry maintained by information about the DHCPv6 "Option Codes" registry maintained by
IANA. IANA.
Unless otherwise noted, each option may appear only in the options Unless otherwise noted, each option may appear only in the options
area of a DHCP message and may appear only once. If an option does area of a DHCP message and may appear only once. If an option does
appear multiple times, each instance is considered separate and the appear multiple times, each instance is considered separate and the
data areas of the options MUST NOT be concatenated or otherwise data areas of the options MUST NOT be concatenated or otherwise
combined. combined.
Options that are allowed to appear only once are called "singleton Options that are allowed to appear only once are called "singleton
skipping to change at page 92, line 23 skipping to change at line 4250
are the IA_NA (see Section 21.4), Vendor Class (see Section 21.16), are the IA_NA (see Section 21.4), Vendor Class (see Section 21.16),
Vendor-specific Information (see Section 21.17), and IA_PD (see Vendor-specific Information (see Section 21.17), and IA_PD (see
Section 21.21) options. Also, IA Address (see Section 21.6) and IA Section 21.21) options. Also, IA Address (see Section 21.6) and IA
Prefix (see Section 21.22) may appear in their respective IA options Prefix (see Section 21.22) may appear in their respective IA options
more than once. more than once.
21.1. Format of DHCP Options 21.1. Format of DHCP Options
The format of DHCP options is: The format of DHCP options is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-code | option-len | | option-code | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-data | | option-data |
| (option-len octets) | | (option-len octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: Option Format Figure 12: Option Format
option-code An unsigned integer identifying the specific option-code: An unsigned integer identifying the specific option
option type carried in this option. type carried in this option. A 2-octet field.
A 2-octet field.
option-len An unsigned integer giving the length of the option-len: An unsigned integer giving the length of the option-data
option-data field in this option in octets. field in this option in octets. A 2-octet field.
A 2-octet field.
option-data The data for the option; the format of this option-data: The data for the option; the format of this data
data depends on the definition of the option. depends on the definition of the option. A variable-length field
A variable-length field (the length, in (the length, in octets, is specified by option-len).
octets, is specified by option-len).
DHCP options are scoped by using encapsulation. Some options apply DHCP options are scoped by using encapsulation. Some options apply
generally to the client, some are specific to an IA, and some are generally to the client, some are specific to an IA, and some are
specific to the addresses within an IA. These latter two cases are specific to the addresses within an IA. These latter two cases are
discussed in Sections 21.4, 21.5, and 21.6. discussed in Sections 21.4, 21.5, and 21.6.
21.2. Client Identifier Option 21.2. Client Identifier Option
The Client Identifier option is used to carry a DUID (see Section 11) The Client Identifier option is used to carry a DUID (see Section 11)
that identifies the client. The format of the Client Identifier that identifies the client. The format of the Client Identifier
option is: option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_CLIENTID | option-len | | OPTION_CLIENTID | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. DUID . . DUID .
. (variable length) . . (variable length) .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 13: Client Identifier Option Format Figure 13: Client Identifier Option Format
option-code OPTION_CLIENTID (1). option-code: OPTION_CLIENTID (1).
option-len Length of DUID in octets. option-len: Length of DUID in octets.
DUID The DUID for the client. DUID: The DUID for the client.
21.3. Server Identifier Option 21.3. Server Identifier Option
The Server Identifier option is used to carry a DUID (see Section 11) The Server Identifier option is used to carry a DUID (see Section 11)
that identifies the server. The format of the Server Identifier that identifies the server. The format of the Server Identifier
option is: option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_SERVERID | option-len | | OPTION_SERVERID | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. DUID . . DUID .
. (variable length) . . (variable length) .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 14: Server Identifier Option Format Figure 14: Server Identifier Option Format
option-code OPTION_SERVERID (2). option-code: OPTION_SERVERID (2).
option-len Length of DUID in octets. option-len: Length of DUID in octets.
DUID The DUID for the server. DUID: The DUID for the server.
21.4. Identity Association for Non-temporary Addresses Option 21.4. Identity Association for Non-Temporary Addresses Option
The Identity Association for Non-temporary Addresses (IA_NA) option The Identity Association for Non-temporary Addresses (IA_NA) option
is used to carry an IA_NA, the parameters associated with the IA_NA, is used to carry an IA_NA, the parameters associated with the IA_NA,
and the non-temporary addresses associated with the IA_NA. and the non-temporary addresses associated with the IA_NA.
A client that needs a short-term / special purpose address can use a A client that needs a short-term / special-purpose address can use a
new IA_NA binding to request an address and release it when finished new IA_NA binding to request an address and release it when finished
with it. with it.
Note: Addresses appearing in an IA_NA option are not temporary Note: Addresses appearing in an IA_NA option are not temporary
addresses (see Section 21.5). addresses (see Section 21.5).
The format of the IA_NA option is: The format of the IA_NA option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_IA_NA | option-len | | OPTION_IA_NA | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IAID (4 octets) | | IAID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| T1 | | T1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| T2 | | T2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. IA_NA-options . . IA_NA-options .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 15: Identity Association for Non-temporary Addresses Figure 15: Identity Association for Non-Temporary Addresses
Option Format Option Format
option-code OPTION_IA_NA (3). option-code: OPTION_IA_NA (3).
option-len 12 + length of IA_NA-options field. option-len: 12 + length of IA_NA-options field.
IAID The unique identifier for this IA_NA; the IAID: The unique identifier for this IA_NA; the IAID must be unique
IAID must be unique among the identifiers for among the identifiers for all of this client's IA_NAs. The number
all of this client's IA_NAs. The number space for IA_NA IAIDs is separate from the number space for other
space for IA_NA IAIDs is separate from the IA option types (i.e., IA_PD). A 4-octet field containing an
number space for other IA option types (i.e., unsigned integer.
IA_PD). A 4-octet field containing an
unsigned integer.
T1 The time interval after which the client T1: The time interval after which the client should contact the
should contact the server from which the server from which the addresses in the IA_NA were obtained to
addresses in the IA_NA were obtained to extend the lifetimes of the addresses assigned to the IA_NA; T1 is
extend the lifetimes of the addresses a time duration relative to the current time expressed in units of
assigned to the IA_NA; T1 is a time duration seconds. A 4-octet field containing an unsigned integer.
relative to the current time expressed in
units of seconds. A 4-octet field containing
an unsigned integer.
T2 The time interval after which the client T2: The time interval after which the client should contact any
should contact any available server to extend available server to extend the lifetimes of the addresses assigned
the lifetimes of the addresses assigned to to the IA_NA; T2 is a time duration relative to the current time
the IA_NA; T2 is a time duration relative to expressed in units of seconds. A 4-octet field containing an
the current time expressed in units of unsigned integer.
seconds. A 4-octet field containing an
unsigned integer.
IA_NA-options Options associated with this IA_NA. A IA_NA-options: Options associated with this IA_NA. A variable-
variable-length field (12 octets less than length field (12 octets less than the value in the option-len
the value in the option-len field). field).
The IA_NA-options field encapsulates those options that are specific The IA_NA-options field encapsulates those options that are specific
to this IA_NA. For example, all of the IA Address options (see to this IA_NA. For example, all of the IA Address options (see
Section 21.6) carrying the addresses associated with this IA_NA are Section 21.6) carrying the addresses associated with this IA_NA are
in the IA_NA-options field. in the IA_NA-options field.
Each IA_NA carries one "set" of non-temporary addresses; it is up to Each IA_NA carries one "set" of non-temporary addresses; it is up to
the server policy to determine how many addresses are assigned, but the server policy to determine how many addresses are assigned, but
typically at most one address is assigned from each prefix assigned typically at most one address is assigned from each prefix assigned
to the link to which the client is attached. to the link to which the client is attached.
skipping to change at page 96, line 38 skipping to change at line 4446
processes the remainder of the message as though the server had not processes the remainder of the message as though the server had not
included the invalid IA_NA option. included the invalid IA_NA option.
21.5. Identity Association for Temporary Addresses Option 21.5. Identity Association for Temporary Addresses Option
The Identity Association for Temporary Addresses (IA_TA) option is The Identity Association for Temporary Addresses (IA_TA) option is
obsoleted. Please refer to [RFC8415] for historical information on obsoleted. Please refer to [RFC8415] for historical information on
this option. this option.
The client SHOULD NOT send this option. The server SHOULD NOT send The client SHOULD NOT send this option. The server SHOULD NOT send
this option. When the server receives IA_TA option, the option this option. When the server receives an IA_TA option, the option
SHOULD be ignored and the message processing should continue as SHOULD be ignored and the message processing should continue as
usual. usual.
As this option was never popular among server or client As this option was never popular among server or client
implementations before being deprecated, any implementations that implementations before being deprecated, any implementations that
still attempt to send it are unlikely to have the option processed. still attempt to send it are unlikely to have the option processed.
21.6. IA Address Option 21.6. IA Address Option
The IA Address option is used to specify an address. In this The IA Address option is used to specify an address. In this
document it is only specified to be encapsulated within an IA_NA. document, it is only specified to be encapsulated within an IA_NA.
DHCPv6 Leasequery [RFC5007] makes use of the IA Address Option DHCPv6 Leasequery [RFC5007] makes use of the IA Address option
without encapsulating it in IA_NA. The IAaddr-options field without encapsulating it in IA_NA. The IAaddr-options field
encapsulates those options that are specific to this address. encapsulates those options that are specific to this address.
The format of the IA Address option is: The format of the IA Address option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_IAADDR | option-len | | OPTION_IAADDR | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
| IPv6-address | | IPv6-address |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| preferred-lifetime | | preferred-lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| valid-lifetime | | valid-lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. IAaddr-options . . IAaddr-options .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 16: IA Address Option Format Figure 16: IA Address Option Format
option-code OPTION_IAADDR (5). option-code: OPTION_IAADDR (5).
option-len 24 + length of IAaddr-options field. option-len: 24 + length of IAaddr-options field.
IPv6-address An IPv6 address. A client MUST NOT form an IPv6-address: An IPv6 address. A client MUST NOT form an implicit
implicit prefix with a length other than 128 prefix with a length other than 128 for this address. A 16-octet
for this address. A 16-octet field. field.
preferred-lifetime The preferred lifetime for the address in the preferred-lifetime: The preferred lifetime for the address in the
option, expressed in units of seconds. A option, expressed in units of seconds. A 4-octet field containing
4-octet field containing an unsigned integer. an unsigned integer.
valid-lifetime The valid lifetime for the address in the valid-lifetime: The valid lifetime for the address in the option,
option, expressed in units of seconds. A expressed in units of seconds. A 4-octet field containing an
4-octet field containing an unsigned integer. unsigned integer.
IAaddr-options Options associated with this address. A IAaddr-options: Options associated with this address. A variable-
variable-length field (24 octets less than length field (24 octets less than the value in the option-len
the value in the option-len field). field).
In a message sent by a client to a server, the preferred-lifetime and In a message sent by a client to a server, the preferred-lifetime and
valid-lifetime fields SHOULD be set to 0. The server MUST ignore any valid-lifetime fields SHOULD be set to 0. The server MUST ignore any
received values. received values.
The client SHOULD NOT send the IA Address option with an unspecified The client SHOULD NOT send the IA Address option with an unspecified
address (::). address (::).
In a message sent by a server to a client, the client MUST use the In a message sent by a server to a client, the client MUST use the
values in the preferred-lifetime and valid-lifetime fields for the values in the preferred-lifetime and valid-lifetime fields for the
skipping to change at page 98, line 32 skipping to change at line 4536
The status of any operations involving this IA Address is indicated The status of any operations involving this IA Address is indicated
in a Status Code option in the IAaddr-options field, as specified in in a Status Code option in the IAaddr-options field, as specified in
Section 21.13. Section 21.13.
21.7. Option Request Option 21.7. Option Request Option
The Option Request option is used to identify a list of options in a The Option Request option is used to identify a list of options in a
message between a client and a server. The format of the Option message between a client and a server. The format of the Option
Request option is: Request option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_ORO | option-len | | OPTION_ORO | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| requested-option-code-1 | requested-option-code-2 | | requested-option-code-1 | requested-option-code-2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... | | ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 17: Option Request Option Format Figure 17: Option Request Option Format
option-code OPTION_ORO (6). option-code: OPTION_ORO (6).
option-len 2 * number of requested options. option-len: 2 * number of requested options.
requested-option-code-n The option code for an option requested requested-option-code-n: The option code for an option requested by
by the client. Each option code is a the client. Each option code is a 2-octet field containing an
2-octet field containing an unsigned unsigned integer.
integer.
A client MUST include an Option Request option in a Solicit, Request, A client MUST include an Option Request option in a Solicit, Request,
Renew, Rebind, or Information-request message to inform the server Renew, Rebind, or Information-request message to inform the server
about options the client wants the server to send to the client. about options the client wants the server to send to the client.
The Option Request option MUST NOT include the following option The Option Request option MUST NOT include the following option
codes: codes:
* Client Identifier (see Section 21.2) * Client Identifier (see Section 21.2)
skipping to change at page 100, line 4 skipping to change at line 4602
* User Class (see Section 21.15) * User Class (see Section 21.15)
* Vendor Class (see Section 21.16) * Vendor Class (see Section 21.16)
* Interface-Id (see Section 21.18) * Interface-Id (see Section 21.18)
* Reconfigure Message (see Section 21.19) * Reconfigure Message (see Section 21.19)
* Reconfigure Accept (see Section 21.20) * Reconfigure Accept (see Section 21.20)
Other top-level option codes MUST appear in the Option Request option Other top-level option codes MUST appear in the Option Request option
or they will not be sent by the server. Only top-level option codes or they will not be sent by the server. Only top-level option codes
MAY appear in the Option Request option. Option codes encapsulated MAY appear in the Option Request option. Option codes encapsulated
in a container option SHOULD NOT appear in an Option Request option; in a container option SHOULD NOT appear in an Option Request option;
see [RFC7598] for an example of container options. However, options see [RFC7598] for an example of container options. However, options
MAY be defined that specify exceptions to this restriction on MAY be defined that specify exceptions to this restriction on
including encapsulated option codes in an Option Request option. For including encapsulated option codes in an Option Request option. For
example, the Option Request option MAY be used to signal support for example, the Option Request option MAY be used to signal support for
a feature even when that option is encapsulated, as in the case of a feature even when that option is encapsulated, as in the case of
the Prefix Exclude option [RFC6603]. See [IANA-OPTION-DETAILS]. the Prefix Exclude option [RFC6603]. See [IANA-OPTION-DETAILS].
See [IANA-OPTION-DETAILS] for the authoritative list of which option See [IANA-OPTION-DETAILS] for the authoritative list of which option
codes are required, permitted or forbidden. codes are required, permitted, or forbidden.
21.8. Preference Option 21.8. Preference Option
The Preference option is sent by a server to a client to control the The Preference option is sent by a server to a client to control the
selection of a server by the client. selection of a server by the client.
The format of the Preference option is: The format of the Preference option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_PREFERENCE | option-len | | OPTION_PREFERENCE | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| pref-value | | pref-value |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 18: Preference Option Format Figure 18: Preference Option Format
option-code OPTION_PREFERENCE (7). option-code: OPTION_PREFERENCE (7).
option-len 1. option-len: 1.
pref-value The preference value for the server in this pref-value: The preference value for the server in this message. A
message. A 1-octet unsigned integer. 1-octet unsigned integer.
A server MAY include a Preference option in an Advertise message to A server MAY include a Preference option in an Advertise message to
control the selection of a server by the client. See Section 18.2.9 control the selection of a server by the client. See Section 18.2.9
for information regarding the use of the Preference option by the for information regarding the use of the Preference option by the
client and the interpretation of the Preference option data value. client and the interpretation of the Preference option data value.
21.9. Elapsed Time Option 21.9. Elapsed Time Option
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
| OPTION_ELAPSED_TIME | option-len | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | OPTION_ELAPSED_TIME | option-len |
| elapsed-time | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | elapsed-time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 19: Elapsed Time Option Format Figure 19: Elapsed Time Option Format
option-code OPTION_ELAPSED_TIME (8). option-code: OPTION_ELAPSED_TIME (8).
option-len 2. option-len: 2.
elapsed-time The amount of time since the client began its elapsed-time: The amount of time since the client began its current
current DHCP transaction. This time is DHCP transaction. This time is expressed in hundredths of a
expressed in hundredths of a second second (10^-2 seconds). A 2-octet field containing an unsigned
(10^-2 seconds). A 2-octet field containing integer.
an unsigned integer.
A client MUST include an Elapsed Time option in messages to indicate A client MUST include an Elapsed Time option in messages to indicate
how long the client has been trying to complete a DHCP message how long the client has been trying to complete a DHCP message
exchange. The elapsed time is measured from the time at which the exchange. The elapsed time is measured from the time at which the
client sent the first message in the message exchange, and the client sent the first message in the message exchange, and the
elapsed-time field is set to 0 in the first message in the message elapsed-time field is set to 0 in the first message in the message
exchange. Servers and relay agents use the data value in this option exchange. Servers and relay agents use the data value in this option
as input to policy that controls how a server responds to a client as input to policy that controls how a server responds to a client
message. For example, the Elapsed Time option allows a secondary message. For example, the Elapsed Time option allows a secondary
DHCP server to respond to a request when a primary server has not DHCP server to respond to a request when a primary server has not
skipping to change at page 102, line 5 skipping to change at line 4688
represent any elapsed-time values greater than the largest time value represent any elapsed-time values greater than the largest time value
that can be represented in the Elapsed Time option. that can be represented in the Elapsed Time option.
21.10. Relay Message Option 21.10. Relay Message Option
The Relay Message option carries a DHCP message in a Relay-forward or The Relay Message option carries a DHCP message in a Relay-forward or
Relay-reply message. Relay-reply message.
The format of the Relay Message option is: The format of the Relay Message option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_RELAY_MSG | option-len | | OPTION_RELAY_MSG | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
. DHCP-relay-message . . DHCP-relay-message .
. . . .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 20: Relay Message Option Format Figure 20: Relay Message Option Format
option-code OPTION_RELAY_MSG (9). option-code: OPTION_RELAY_MSG (9).
option-len Length of DHCP-relay-message field. option-len: Length of DHCP-relay-message field.
DHCP-relay-message In a Relay-forward message, the received DHCP-relay-message: In a Relay-forward message, the received
message, relayed verbatim to the next relay message, relayed verbatim to the next relay agent or server; in a
agent or server; in a Relay-reply message, Relay-reply message, the message to be copied and relayed to the
the message to be copied and relayed to the relay agent or client whose address is in the peer-address field
relay agent or client whose address is in the of the Relay-reply message. The length, in octets, is specified
peer-address field of the Relay-reply by option-len.
message. The length, in octets, is specified
by option-len.
21.11. Authentication Option 21.11. Authentication Option
The Authentication option carries authentication information to The Authentication option carries authentication information to
authenticate the identity and contents of DHCP messages. The use of authenticate the identity and contents of DHCP messages. The use of
the Authentication option is described in Section 20. The format of the Authentication option is described in Section 20. The format of
the Authentication option is: the Authentication option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_AUTH | option-len | | OPTION_AUTH | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| protocol | algorithm | RDM | | | protocol | algorithm | RDM | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | | |
| replay detection (64 bits) +-+-+-+-+-+-+-+-+ | replay detection (64 bits) +-+-+-+-+-+-+-+-+
| | | | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
. authentication information . . authentication information .
. (variable length) . . (variable length) .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 21: Authentication Option Format Figure 21: Authentication Option Format
option-code OPTION_AUTH (11). option-code: OPTION_AUTH (11).
option-len 11 + length of authentication option-len: 11 + length of authentication information field.
information field.
protocol The authentication protocol used in protocol: The authentication protocol used in this Authentication
this Authentication option. A option. A 1-octet unsigned integer.
1-octet unsigned integer.
algorithm The algorithm used in the algorithm: The algorithm used in the authentication protocol. A
authentication protocol. A 1-octet 1-octet unsigned integer.
unsigned integer.
RDM The replay detection method used in RDM: The replay detection method used in this Authentication option.
this Authentication option. A A 1-octet unsigned integer.
1-octet unsigned integer.
replay detection The replay detection information for replay detection: The replay detection information for the RDM. A
the RDM. A 64-bit (8-octet) field. 64-bit (8-octet) field.
authentication information The authentication information, as authentication information: The authentication information, as
specified by the protocol and specified by the protocol and algorithm used in this
algorithm used in this Authentication Authentication option. A variable-length field (11 octets less
option. A variable-length field than the value in the option-len field).
(11 octets less than the value in the
option-len field).
IANA maintains a registry for the protocol, algorithm, and RDM values IANA maintains a registry for the protocol, algorithm, and RDM values
at <https://www.iana.org/assignments/auth-namespaces>. at <https://www.iana.org/assignments/auth-namespaces>.
21.12. Server Unicast Option 21.12. Server Unicast Option
The Server Unicast option is obsolete. Please refer to [RFC8415] for The Server Unicast option is obsolete. Please refer to [RFC8415] for
historical information on this option. historical information on this option.
The client SHOULD NOT request this option in the Option Request The client SHOULD NOT request this option in the Option Request
option. The server SHOULD NOT send this option, even when requested option. The server SHOULD NOT send this option, even when requested
by clients. When any entity receives the Server Unicast option, the by clients. When any entity receives the Server Unicast option, the
option SHOULD be ignored and the message processing should continue option SHOULD be ignored and the message processing should continue
as usual. as usual.
As this option was not very popular and it typically required special As this option was not very popular, and it typically required
configuration by those server implementations that did support it, special configuration by those server implementations that did
clients still requesting this option in the Option Request option are support it, clients still requesting this option in the Option
increasingly unlikely to receive it. Request option are increasingly unlikely to receive it.
21.13. Status Code Option 21.13. Status Code Option
This option returns a status indication related to the DHCP message This option returns a status indication related to the DHCP message
or option in which it appears. The format of the Status Code or option in which it appears. The format of the Status Code option
option is: is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_STATUS_CODE | option-len | | OPTION_STATUS_CODE | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| status-code | | | status-code | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
. . . .
. status-message . . status-message .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 22: Status Code Option Format Figure 22: Status Code Option Format
option-code OPTION_STATUS_CODE (13). option-code: OPTION_STATUS_CODE (13).
option-len 2 + length of status-message field. option-len: 2 + length of status-message field.
status-code The numeric code for the status encoded in status-code: The numeric code for the status encoded in this option.
this option. A 2-octet field containing an A 2-octet field containing an unsigned integer.
unsigned integer.
status-message A UTF-8 encoded [RFC3629] text string status-message: A UTF-8 encoded [RFC3629] text string suitable for
suitable for display to an end user. display to an end user. MUST NOT be null-terminated. A variable-
MUST NOT be null-terminated. A variable- length field (2 octets less than the value in the option-len
length field (2 octets less than the value in field).
the option-len field).
A Status Code option may appear in the "options" field of a DHCP A Status Code option may appear in the "options" field of a DHCP
message and/or in the "options" field of another option. If the message and/or in the "options" field of another option. If the
Status Code option does not appear in a message in which the option Status Code option does not appear in a message in which the option
could appear, the status of the message is assumed to be Success. could appear, the status of the message is assumed to be Success.
The status-code values are: The status-code values are:
+===============+======+===================================+ +===============+======+===================================+
| Name | Code | Description | | Name | Code | Description |
skipping to change at page 106, line 5 skipping to change at line 4859
See the "Status Codes" registry at <https://www.iana.org/assignments/ See the "Status Codes" registry at <https://www.iana.org/assignments/
dhcpv6-parameters> for the current list of status codes. dhcpv6-parameters> for the current list of status codes.
21.14. Rapid Commit Option 21.14. Rapid Commit Option
The Rapid Commit option is used to signal the use of the two-message The Rapid Commit option is used to signal the use of the two-message
exchange for address assignment. The format of the Rapid Commit exchange for address assignment. The format of the Rapid Commit
option is: option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_RAPID_COMMIT | option-len | | OPTION_RAPID_COMMIT | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 23: Rapid Commit Option Format Figure 23: Rapid Commit Option Format
option-code OPTION_RAPID_COMMIT (14). option-code: OPTION_RAPID_COMMIT (14).
option-len 0. option-len: 0.
A client MAY include this option in a Solicit message if the client A client MAY include this option in a Solicit message if the client
is prepared to perform the Solicit/Reply message exchange described is prepared to perform the Solicit/Reply message exchange described
in Section 18.2.1. in Section 18.2.1.
A server MUST include this option in a Reply message sent in response A server MUST include this option in a Reply message sent in response
to a Solicit message when completing the Solicit/Reply message to a Solicit message when completing the Solicit/Reply message
exchange. exchange.
DISCUSSION: DISCUSSION:
Each server that responds with a Reply to a Solicit that includes * Each server that responds with a Reply to a Solicit that includes
a Rapid Commit option will commit the leases in the Reply message a Rapid Commit option will commit the leases in the Reply message
to the client but will not receive any confirmation that the to the client but will not receive any confirmation that the
client has received the Reply message. Therefore, if more than client has received the Reply message. Therefore, if more than
one server responds to a Solicit that includes a Rapid Commit one server responds to a Solicit that includes a Rapid Commit
option, all but one server will commit leases that are not option, all but one server will commit leases that are not
actually used by the client; this could result in incorrect actually used by the client; this could result in incorrect
address information in DNS if the DHCP servers update DNS address information in DNS if the DHCP servers update DNS
[RFC4704], and responses to leasequery requests [RFC5007] may [RFC4704], and responses to leasequery requests [RFC5007] may
include information on leases not in use by the client. include information on leases not in use by the client.
The problem of unused leases can be minimized by designing the * The problem of unused leases can be minimized by designing the
DHCP service so that only one server responds to the Solicit or by DHCP service so that only one server responds to the Solicit or by
using relatively short lifetimes for newly assigned leases. using relatively short lifetimes for newly assigned leases.
21.15. User Class Option 21.15. User Class Option
The User Class option is used by a client to identify the type or The User Class option is used by a client to identify the type or
category of users or applications it represents. category of users or applications it represents.
The format of the User Class option is: The format of the User Class option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_USER_CLASS | option-len | | OPTION_USER_CLASS | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. user-class-data . . user-class-data .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 24: User Class Option Format Figure 24: User Class Option Format
option-code OPTION_USER_CLASS (15). option-code: OPTION_USER_CLASS (15).
option-len Length of user-class-data field. option-len: Length of user-class-data field.
user-class-data The user classes carried by the client. The user-class-data: The user classes carried by the client. The
length, in octets, is specified by length, in octets, is specified by option-len.
option-len.
The information contained in the data area of this option is The information contained in the data area of this option is
contained in one or more opaque fields that represent the user class contained in one or more opaque fields that represent the user class
or classes of which the client is a member. A server selects or classes of which the client is a member. A server selects
configuration information for the client based on the classes configuration information for the client based on the classes
identified in this option. For example, the User Class option can be identified in this option. For example, the User Class option can be
used to configure all clients of people in the accounting department used to configure all clients of people in the accounting department
with a different printer than clients of people in the marketing with a different printer than clients of people in the marketing
department. The user class information carried in this option MUST department. The user class information carried in this option MUST
be configurable on the client. be configurable on the client.
The data area of the User Class option MUST contain one or more The data area of the User Class option MUST contain one or more
instances of user-class-data information. Each instance of instances of user-class-data information. Each instance of user-
user-class-data is formatted as follows: class-data is formatted as follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+-+-+-+-+-+-+
| user-class-len | opaque-data | | user-class-len | opaque-data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+-+-+-+-+-+-+
Figure 25: Format of user-class-data Field Figure 25: Format of user-class-data Field
The user-class-len field is 2 octets long and specifies the length of The user-class-len field is 2 octets long and specifies the length of
the opaque user-class-data in network byte order. the opaque user-class-data in network byte order.
A server interprets the classes identified in this option according A server interprets the classes identified in this option according
to its configuration to select the appropriate configuration to its configuration to select the appropriate configuration
information for the client. A server may use only those user classes information for the client. A server may use only those user classes
that it is configured to interpret in selecting configuration that it is configured to interpret in selecting configuration
skipping to change at page 108, line 17 skipping to change at line 4963
informed of the classes interpreted by the server. informed of the classes interpreted by the server.
21.16. Vendor Class Option 21.16. Vendor Class Option
This option is used by a client to identify the vendor that This option is used by a client to identify the vendor that
manufactured the hardware on which the client is running. The manufactured the hardware on which the client is running. The
information contained in the data area of this option is contained in information contained in the data area of this option is contained in
one or more opaque fields that identify details of the hardware one or more opaque fields that identify details of the hardware
configuration. The format of the Vendor Class option is: configuration. The format of the Vendor Class option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_VENDOR_CLASS | option-len | | OPTION_VENDOR_CLASS | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| enterprise-number | | enterprise-number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. vendor-class-data . . vendor-class-data .
. . . . . . . . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 26: Vendor Class Option Format Figure 26: Vendor Class Option Format
option-code OPTION_VENDOR_CLASS (16). option-code: OPTION_VENDOR_CLASS (16).
option-len 4 + length of vendor-class-data field. option-len: 4 + length of vendor-class-data field.
enterprise-number The vendor's registered Enterprise Number as enterprise-number: The vendor's registered Enterprise Number as
maintained by IANA [IANA-PEN]. A 4-octet maintained by IANA [IANA-PEN]. A 4-octet field containing an
field containing an unsigned integer. unsigned integer.
vendor-class-data The hardware configuration of the node on vendor-class-data: The hardware configuration of the node on which
which the client is running. A the client is running. A variable-length field (4 octets less
variable-length field (4 octets less than the than the value in the option-len field).
value in the option-len field).
The vendor-class-data field is composed of a series of separate The vendor-class-data field is composed of a series of separate
items, each of which describes some characteristic of the client's items, each of which describes some characteristic of the client's
hardware configuration. Examples of vendor-class-data instances hardware configuration. Examples of vendor-class-data instances
might include the version of the operating system the client is might include the version of the operating system the client is
running or the amount of memory installed on the client. running or the amount of memory installed on the client.
Each instance of vendor-class-data is formatted as follows: Each instance of vendor-class-data is formatted as follows:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+-+-+-+-+-+-+
| vendor-class-len | opaque-data | | vendor-class-len | opaque-data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...-+-+-+-+-+-+-+
Figure 27: Format of vendor-class-data Field Figure 27: Format of vendor-class-data Field
The vendor-class-len field is 2 octets long and specifies the length The vendor-class-len field is 2 octets long and specifies the length
of the opaque vendor-class-data in network byte order. of the opaque vendor-class-data in network byte order.
Servers and clients MUST NOT include more than one instance of Servers and clients MUST NOT include more than one instance of
OPTION_VENDOR_CLASS with the same Enterprise Number. Each instance OPTION_VENDOR_CLASS with the same Enterprise Number. Each instance
of OPTION_VENDOR_CLASS can carry multiple vendor-class-data of OPTION_VENDOR_CLASS can carry multiple vendor-class-data
instances. instances.
21.17. Vendor-specific Information Option 21.17. Vendor-Specific Information Option
This option is used by clients and servers to exchange vendor- This option is used by clients and servers to exchange vendor-
specific information. specific information.
The format of the Vendor-specific Information option is: The format of the Vendor-specific Information option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_VENDOR_OPTS | option-len | | OPTION_VENDOR_OPTS | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| enterprise-number | | enterprise-number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. vendor-option-data . . vendor-option-data .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 28: Vendor-specific Information Option Format Figure 28: Vendor-Specific Information Option Format
option-code OPTION_VENDOR_OPTS (17). option-code: OPTION_VENDOR_OPTS (17).
option-len 4 + length of vendor-option-data field. option-len: 4 + length of vendor-option-data field.
enterprise-number The vendor's registered Enterprise Number as enterprise-number: The vendor's registered Enterprise Number as
maintained by IANA [IANA-PEN]. A 4-octet maintained by IANA [IANA-PEN]. A 4-octet field containing an
field containing an unsigned integer. unsigned integer.
vendor-option-data Vendor options, interpreted by vendor- vendor-option-data: Vendor options, interpreted by vendor-specific
specific code on the clients and servers. A code on the clients and servers. A variable-length field (4
variable-length field (4 octets less than the octets less than the value in the option-len field).
value in the option-len field).
The definition of the information carried in this option is vendor The definition of the information carried in this option is vendor
specific. The vendor is indicated in the enterprise-number field. specific. The vendor is indicated in the enterprise-number field.
Use of vendor-specific information allows enhanced operation, Use of vendor-specific information allows enhanced operation,
utilizing additional features in a vendor's DHCP implementation. A utilizing additional features in a vendor's DHCP implementation. A
DHCP client that does not receive requested vendor-specific DHCP client that does not receive requested vendor-specific
information will still configure the node's IPv6 stack to be information will still configure the node's IPv6 stack to be
functional. functional.
The vendor-option-data field MUST be encoded as a sequence of The vendor-option-data field MUST be encoded as a sequence of
code/length/value fields of format identical to the DHCP options (see code/length/value fields of format identical to the DHCP options (see
Section 21.1). The suboption codes are defined by the vendor Section 21.1). The suboption codes are defined by the vendor
identified in the enterprise-number field and are not managed by identified in the enterprise-number field and are not managed by
IANA. Each of the suboptions is formatted as follows: IANA. Each of the suboptions is formatted as follows:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| sub-opt-code | suboption-len | | sub-opt-code | suboption-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. suboption-data . . suboption-data .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 29: Vendor-specific Options Format Figure 29: Vendor-Specific Options Format
sub-opt-code The code for the suboption. A 2-octet field. sub-opt-code: The code for the suboption. A 2-octet field.
suboption-len An unsigned integer giving the length of the suboption-len: An unsigned integer giving the length of the
suboption-data field in this suboption in suboption-data field in this suboption in octets. A 2-octet
octets. A 2-octet field. field.
suboption-data The data area for the suboption. The length, suboption-data: The data area for the suboption. The length, in
in octets, is specified by sub-option-len. octets, is specified by suboption-len.
Multiple instances of the Vendor-specific Information option may Multiple instances of the Vendor-specific Information option may
appear in a DHCP message. Each instance of the option is interpreted appear in a DHCP message. Each instance of the option is interpreted
according to the option codes defined by the vendor identified by the according to the option codes defined by the vendor identified by the
Enterprise Number in that option. Servers and clients MUST NOT send Enterprise Number in that option. Servers and clients MUST NOT send
more than one instance of the Vendor-specific Information option with more than one instance of the Vendor-specific Information option with
the same Enterprise Number. Each instance of the Vendor-specific the same Enterprise Number. Each instance of the Vendor-specific
Information option MAY contain multiple suboptions. Information option MAY contain multiple suboptions.
A client that is interested in receiving a Vendor-specific A client that is interested in receiving a Vendor-specific
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* MAY specify an associated Vendor Class option (see Section 21.16). * MAY specify an associated Vendor Class option (see Section 21.16).
* MAY specify the Vendor-specific Information option with * MAY specify the Vendor-specific Information option with
appropriate data. appropriate data.
Servers only return the Vendor-specific Information options if Servers only return the Vendor-specific Information options if
specified in Option Request options from clients and: specified in Option Request options from clients and:
* MAY use the Enterprise Numbers in the associated Vendor Class * MAY use the Enterprise Numbers in the associated Vendor Class
options to restrict the set of Enterprise Numbers in the options to restrict the set of Enterprise Numbers in the Vendor-
Vendor-specific Information options returned. specific Information options returned.
* MAY return all configured Vendor-specific Information options. * MAY return all configured Vendor-specific Information options.
* MAY use other information in the message or in its configuration * MAY use other information in the message or in its configuration
to determine which set of Enterprise Numbers in the Vendor- to determine which set of Enterprise Numbers in the Vendor-
specific Information options to return. specific Information options to return.
21.18. Interface-Id Option 21.18. Interface-Id Option
The relay agent MAY send the Interface-Id option to identify the The relay agent MAY send the Interface-Id option to identify the
interface on which the client message was received. If a relay agent interface on which the client message was received. If a relay agent
receives a Relay-reply message with an Interface-Id option, the relay receives a Relay-reply message with an Interface-Id option, the relay
agent relays the message to the client through the interface agent relays the message to the client through the interface
identified by the option. identified by the option.
The format of the Interface-Id option is: The format of the Interface-Id option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_INTERFACE_ID | option-len | | OPTION_INTERFACE_ID | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. interface-id . . interface-id .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 30: Interface-Id Option Format Figure 30: Interface-Id Option Format
option-code OPTION_INTERFACE_ID (18). option-code: OPTION_INTERFACE_ID (18).
option-len Length of interface-id field. option-len: Length of interface-id field.
interface-id An opaque value of arbitrary length generated interface-id: An opaque value of arbitrary length generated by the
by the relay agent to identify one of the relay agent to identify one of the relay agent's interfaces. The
relay agent's interfaces. The length, in length, in octets, is specified by option-len.
octets, is specified by option-len.
The server MUST copy the Interface-Id option from the Relay-forward The server MUST copy the Interface-Id option from the Relay-forward
message into the Relay-reply message the server sends to the relay message into the Relay-reply message the server sends to the relay
agent in response to the Relay-forward message. This option MUST NOT agent in response to the Relay-forward message. This option MUST NOT
appear in any message except a Relay-forward or Relay-reply message. appear in any message except a Relay-forward or Relay-reply message.
Servers MAY use the interface-id field for parameter assignment Servers MAY use the interface-id field for parameter assignment
policies. The interface-id value SHOULD be considered an opaque policies. The interface-id value SHOULD be considered an opaque
value, with policies based on exact match only; that is, the value, with policies based on exact match only; that is, the
interface-id field SHOULD NOT be internally parsed by the server. interface-id field SHOULD NOT be internally parsed by the server.
skipping to change at page 112, line 26 skipping to change at line 5162
interface-id value changes, a server will not be able to use it interface-id value changes, a server will not be able to use it
reliably in parameter assignment policies. reliably in parameter assignment policies.
21.19. Reconfigure Message Option 21.19. Reconfigure Message Option
A server includes a Reconfigure Message option in a Reconfigure A server includes a Reconfigure Message option in a Reconfigure
message to indicate to the client whether the client responds with a message to indicate to the client whether the client responds with a
Renew message, a Rebind message, or an Information-request message. Renew message, a Rebind message, or an Information-request message.
The format of the Reconfigure Message option is: The format of the Reconfigure Message option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_RECONF_MSG | option-len | | OPTION_RECONF_MSG | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| msg-type | | msg-type |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 31: Reconfigure Message Option Format Figure 31: Reconfigure Message Option Format
option-code OPTION_RECONF_MSG (19). option-code: OPTION_RECONF_MSG (19).
option-len 1. option-len: 1.
msg-type 5 for Renew message, 6 for Rebind message, msg-type: 5 for Renew message, 6 for Rebind message, 11 for
11 for Information-request message. A Information-request message. A 1-octet unsigned integer.
1-octet unsigned integer.
The Reconfigure Message option can only appear in a Reconfigure The Reconfigure Message option can only appear in a Reconfigure
message. message.
21.20. Reconfigure Accept Option 21.20. Reconfigure Accept Option
A client uses the Reconfigure Accept option to announce to the server A client uses the Reconfigure Accept option to announce to the server
whether the client is willing to accept Reconfigure messages, and a whether the client is willing to accept Reconfigure messages, and a
server uses this option to tell the client whether or not to accept server uses this option to tell the client whether or not to accept
Reconfigure messages. In the absence of this option, the default Reconfigure messages. In the absence of this option, the default
behavior is that the client is unwilling to accept Reconfigure behavior is that the client is unwilling to accept Reconfigure
messages. The format of the Reconfigure Accept option is: messages. The format of the Reconfigure Accept option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_RECONF_ACCEPT | option-len | | OPTION_RECONF_ACCEPT | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 32: Reconfigure Accept Option Format Figure 32: Reconfigure Accept Option Format
option-code OPTION_RECONF_ACCEPT (20). option-code: OPTION_RECONF_ACCEPT (20).
option-len 0. option-len: 0.
21.21. Identity Association for Prefix Delegation Option 21.21. Identity Association for Prefix Delegation Option
The IA_PD option is used to carry a prefix delegation identity The IA_PD option is used to carry a prefix delegation identity
association, the parameters associated with the IA_PD, and the association, the parameters associated with the IA_PD, and the
prefixes associated with it. The format of the IA_PD option is: prefixes associated with it. The format of the IA_PD option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_IA_PD | option-len | | OPTION_IA_PD | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IAID (4 octets) | | IAID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| T1 | | T1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| T2 | | T2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. IA_PD-options . . IA_PD-options .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 33: Identity Association for Prefix Delegation Option Format Figure 33: Identity Association for Prefix Delegation Option Format
option-code OPTION_IA_PD (25). option-code: OPTION_IA_PD (25).
option-len 12 + length of IA_PD-options field. option-len: 12 + length of IA_PD-options field.
IAID The unique identifier for this IA_PD; the IAID: The unique identifier for this IA_PD; the IAID must be unique
IAID must be unique among the identifiers for among the identifiers for all of this client's IA_PDs. The number
all of this client's IA_PDs. The number space for IA_PD IAIDs is separate from the number space for other
space for IA_PD IAIDs is separate from the IA option types (i.e., IA_NA). A 4-octet field containing an
number space for other IA option types (i.e., unsigned integer.
IA_NA). A 4-octet field containing an
unsigned integer.
T1 The time interval after which the client T1: The time interval after which the client should contact the
should contact the server from which the server from which the prefixes in the IA_PD were obtained to
prefixes in the IA_PD were obtained to extend extend the lifetimes of the prefixes delegated to the IA_PD; T1 is
the lifetimes of the prefixes delegated to a time duration relative to the message reception time expressed
the IA_PD; T1 is a time duration relative to in units of seconds. A 4-octet field containing an unsigned
the message reception time expressed in units integer.
of seconds. A 4-octet field containing an
unsigned integer.
T2 The time interval after which the client T2: The time interval after which the client should contact any
should contact any available server to extend available server to extend the lifetimes of the prefixes assigned
the lifetimes of the prefixes assigned to the to the IA_PD; T2 is a time duration relative to the message
IA_PD; T2 is a time duration relative to the reception time expressed in units of seconds. A 4-octet field
message reception time expressed in units of containing an unsigned integer.
seconds. A 4-octet field containing an
unsigned integer.
IA_PD-options Options associated with this IA_PD. A IA_PD-options: Options associated with this IA_PD. A variable-
variable-length field (12 octets less than length field (12 octets less than the value in the option-len
the value in the option-len field). field).
The IA_PD-options field encapsulates those options that are specific The IA_PD-options field encapsulates those options that are specific
to this IA_PD. For example, all of the IA Prefix options (see to this IA_PD. For example, all of the IA Prefix options (see
Section 21.22) carrying the prefixes associated with this IA_PD are Section 21.22) carrying the prefixes associated with this IA_PD are
in the IA_PD-options field. in the IA_PD-options field.
An IA_PD option may only appear in the options area of a DHCP An IA_PD option may only appear in the options area of a DHCP
message. A DHCP message may contain multiple IA_PD options (though message. A DHCP message may contain multiple IA_PD options (though
each must have a unique IAID). each must have a unique IAID).
skipping to change at page 115, line 32 skipping to change at line 5299
MUST follow the rules defined in Section 14.2. MUST follow the rules defined in Section 14.2.
If a client receives an IA_PD with T1 greater than T2 and both T1 and If a client receives an IA_PD with T1 greater than T2 and both T1 and
T2 are greater than 0, the client discards the IA_PD option and T2 are greater than 0, the client discards the IA_PD option and
processes the remainder of the message as though the server had not processes the remainder of the message as though the server had not
included the IA_PD option. included the IA_PD option.
21.22. IA Prefix Option 21.22. IA Prefix Option
The IA Prefix option is used to specify a prefix associated with an The IA Prefix option is used to specify a prefix associated with an
IA_PD. The IA Prefix option must be encapsulated in the IA_PD. The IA Prefix option must be encapsulated in the IA_PD-
IA_PD-options field of an IA_PD option (see Section 21.21). options field of an IA_PD option (see Section 21.21).
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_IAPREFIX | option-len | | OPTION_IAPREFIX | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| preferred-lifetime | | preferred-lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| valid-lifetime | | valid-lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| prefix-length | | | prefix-length | |
+-+-+-+-+-+-+-+-+ IPv6-prefix | +-+-+-+-+-+-+-+-+ IPv6-prefix |
| (16 octets) | | (16 octets) |
| | | |
| | | |
| | | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | . | | .
+-+-+-+-+-+-+-+-+ . +-+-+-+-+-+-+-+-+ .
. IAprefix-options . . IAprefix-options .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 34: IA Prefix Option Format Figure 34: IA Prefix Option Format
option-code OPTION_IAPREFIX (26). option-code: OPTION_IAPREFIX (26).
option-len 25 + length of IAprefix-options field. option-len: 25 + length of IAprefix-options field.
preferred-lifetime The preferred lifetime for the prefix in the preferred-lifetime: The preferred lifetime for the prefix in the
option, expressed in units of seconds. A option, expressed in units of seconds. A value of 0xffffffff
value of 0xffffffff represents "infinity" represents "infinity" (see Section 7.7). A 4-octet field
(see Section 7.7). A 4-octet field containing an unsigned integer.
containing an unsigned integer.
valid-lifetime The valid lifetime for the prefix in the valid-lifetime: The valid lifetime for the prefix in the option,
option, expressed in units of seconds. A expressed in units of seconds. A value of 0xffffffff represents
value of 0xffffffff represents "infinity". A "infinity". A 4-octet field containing an unsigned integer.
4-octet field containing an unsigned integer.
prefix-length Length for this prefix in bits. A 1-octet prefix-length: Length for this prefix in bits. A 1-octet unsigned
unsigned integer. integer.
IPv6-prefix An IPv6 prefix. A 16-octet field. IPv6-prefix: An IPv6 prefix. A 16-octet field.
IAprefix-options Options associated with this prefix. A IAprefix-options: Options associated with this prefix. A variable-
variable-length field (25 octets less than length field (25 octets less than the value in the option-len
the value in the option-len field). field).
In a message sent by a client to a server, the preferred-lifetime and In a message sent by a client to a server, the preferred-lifetime and
valid-lifetime fields SHOULD be set to 0. The server MUST ignore any valid-lifetime fields SHOULD be set to 0. The server MUST ignore any
received values in these lifetime fields. received values in these lifetime fields.
The client SHOULD NOT send an IA Prefix option with 0 in the The client SHOULD NOT send an IA Prefix option with 0 in the "prefix-
"prefix-length" field (and an unspecified value (::) in the length" field (and an unspecified value (::) in the "IPv6-prefix"
"IPv6-prefix" field). A client MAY send a non-zero value in the field). A client MAY send a non-zero value in the "prefix-length"
"prefix-length" field and the unspecified value (::) in the field and the unspecified value (::) in the "IPv6-prefix" field to
"IPv6-prefix" field to indicate a preference for the size of the indicate a preference for the size of the prefix to be delegated.
prefix to be delegated. See [RFC8168] for further details on prefix- See [RFC8168] for further details on prefix-length hints.
length hints.
The client MUST discard any prefixes for which the preferred lifetime The client MUST discard any prefixes for which the preferred lifetime
is greater than the valid lifetime. is greater than the valid lifetime.
The values in the preferred-lifetime and valid-lifetime fields are The values in the preferred-lifetime and valid-lifetime fields are
the number of seconds remaining in each lifetime. See the number of seconds remaining in each lifetime. See
Section 18.2.10.1 for more details on how these values are used for Section 18.2.10.1 for more details on how these values are used for
delegated prefixes. delegated prefixes.
As per Section 7.7, the value of 0xffffffff for the preferred As per Section 7.7, the value of 0xffffffff for the preferred
skipping to change at page 118, line 5 skipping to change at line 5392
refreshing information retrieved from a DHCP server. It is only used refreshing information retrieved from a DHCP server. It is only used
in Reply messages in response to Information-request messages. In in Reply messages in response to Information-request messages. In
other messages, there will usually be other information that other messages, there will usually be other information that
indicates when the client should contact the server, e.g., T1/T2 indicates when the client should contact the server, e.g., T1/T2
times and lifetimes. This option is useful when the configuration times and lifetimes. This option is useful when the configuration
parameters change or during a renumbering event, as clients running parameters change or during a renumbering event, as clients running
in the stateless mode will be able to update their configuration. in the stateless mode will be able to update their configuration.
The format of the Information Refresh Time option is: The format of the Information Refresh Time option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|OPTION_INFORMATION_REFRESH_TIME| option-len | |OPTION_INFORMATION_REFRESH_TIME| option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| information-refresh-time | | information-refresh-time |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 35: Information Refresh Time Option Format Figure 35: Information Refresh Time Option Format
option-code OPTION_INFORMATION_REFRESH_TIME (32). option-code: OPTION_INFORMATION_REFRESH_TIME (32).
option-len 4. option-len: 4.
information-refresh-time Time duration relative to the current information-refresh-time: Time duration relative to the current
time, expressed in units of seconds. A time, expressed in units of seconds. A 4-octet field containing
4-octet field containing an unsigned an unsigned integer.
integer.
A DHCP client MUST request this option in the Option Request option A DHCP client MUST request this option in the Option Request option
(see Section 21.7) when sending Information-request messages. A (see Section 21.7) when sending Information-request messages. A
client MUST NOT request this option in the Option Request option in client MUST NOT request this option in the Option Request option in
any other messages. any other messages.
A server sending a Reply to an Information-request message SHOULD A server sending a Reply to an Information-request message SHOULD
include this option if it is requested in the Option Request option include this option if it is requested in the Option Request option
of the Information-request. The option value MUST NOT be smaller of the Information-request. The option value MUST NOT be smaller
than IRT_MINIMUM. This option MUST only appear in the top-level than IRT_MINIMUM. This option MUST only appear in the top-level
skipping to change at page 119, line 6 skipping to change at line 5438
As per Section 7.7, the value 0xffffffff is taken to mean "infinity" As per Section 7.7, the value 0xffffffff is taken to mean "infinity"
and implies that the client should not refresh its configuration data and implies that the client should not refresh its configuration data
without some other trigger (such as detecting movement to a new without some other trigger (such as detecting movement to a new
link). link).
If a client contacts the server to obtain new data or refresh some If a client contacts the server to obtain new data or refresh some
existing data before the refresh time expires, then it SHOULD also existing data before the refresh time expires, then it SHOULD also
refresh all data covered by this option. refresh all data covered by this option.
When the client detects that the refresh time has expired, it SHOULD When the client detects that the refresh time has expired, it SHOULD
try to update its configuration data by sending an try to update its configuration data by sending an Information-
Information-request as specified in Section 18.2.6, except that the request as specified in Section 18.2.6, except that the client MUST
client MUST delay sending the first Information-request by a random delay sending the first Information-request by a random amount of
amount of time between 0 and INF_MAX_DELAY. time between 0 and INF_MAX_DELAY.
A client MAY have a maximum value for the refresh time, where that A client MAY have a maximum value for the refresh time, where that
value is used whenever the client receives this option with a value value is used whenever the client receives this option with a value
higher than the maximum. This also means that the maximum value is higher than the maximum. This also means that the maximum value is
used when the received value is "infinity". A maximum value might used when the received value is "infinity". A maximum value might
make the client less vulnerable to attacks based on forged DHCP make the client less vulnerable to attacks based on forged DHCP
messages. Without a maximum value, a client may be made to use wrong messages. Without a maximum value, a client may be made to use wrong
information for a possibly infinite period of time. There may, information for a possibly infinite period of time. There may,
however, be reasons for having a very long refresh time, so it may be however, be reasons for having a very long refresh time, so it may be
useful for this maximum value to be configurable. useful for this maximum value to be configurable.
skipping to change at page 119, line 32 skipping to change at line 5464
A DHCP server sends the SOL_MAX_RT option to a client to override the A DHCP server sends the SOL_MAX_RT option to a client to override the
default value of SOL_MAX_RT. The value of SOL_MAX_RT in the option default value of SOL_MAX_RT. The value of SOL_MAX_RT in the option
replaces the default value defined in Section 7.6. One use for the replaces the default value defined in Section 7.6. One use for the
SOL_MAX_RT option is to set a higher value for SOL_MAX_RT; this SOL_MAX_RT option is to set a higher value for SOL_MAX_RT; this
reduces the Solicit traffic from a client that has not received a reduces the Solicit traffic from a client that has not received a
response to its Solicit messages. response to its Solicit messages.
The format of the SOL_MAX_RT option is: The format of the SOL_MAX_RT option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_SOL_MAX_RT | option-len | | OPTION_SOL_MAX_RT | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SOL_MAX_RT value | | SOL_MAX_RT value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 36: SOL_MAX_RT Option Format Figure 36: SOL_MAX_RT Option Format
option-code OPTION_SOL_MAX_RT (82). option-code: OPTION_SOL_MAX_RT (82).
option-len 4. option-len: 4.
SOL_MAX_RT value Overriding value for SOL_MAX_RT in seconds; SOL_MAX_RT value: Overriding value for SOL_MAX_RT in seconds; MUST
MUST be in this range: 60 <= "value" <= 86400 be in this range: 60 <= "value" <= 86400 (1 day). A 4-octet field
(1 day). A 4-octet field containing an containing an unsigned integer.
unsigned integer.
A DHCP client MUST include the SOL_MAX_RT option code in any Option A DHCP client MUST include the SOL_MAX_RT option code in any Option
Request option (see Section 21.7) it sends in a Solicit message. Request option (see Section 21.7) it sends in a Solicit message.
The DHCP server MAY include the SOL_MAX_RT option in any response it The DHCP server MAY include the SOL_MAX_RT option in any response it
sends to a client that has included the SOL_MAX_RT option code in an sends to a client that has included the SOL_MAX_RT option code in an
Option Request option. The SOL_MAX_RT option is sent as a top-level Option Request option. The SOL_MAX_RT option is sent as a top-level
option in the message to the client. option in the message to the client.
A DHCP client MUST ignore any SOL_MAX_RT option values that are less A DHCP client MUST ignore any SOL_MAX_RT option values that are less
skipping to change at page 120, line 38 skipping to change at line 5518
A DHCP server sends the INF_MAX_RT option to a client to override the A DHCP server sends the INF_MAX_RT option to a client to override the
default value of INF_MAX_RT. The value of INF_MAX_RT in the option default value of INF_MAX_RT. The value of INF_MAX_RT in the option
replaces the default value defined in Section 7.6. One use for the replaces the default value defined in Section 7.6. One use for the
INF_MAX_RT option is to set a higher value for INF_MAX_RT; this INF_MAX_RT option is to set a higher value for INF_MAX_RT; this
reduces the Information-request traffic from a client that has not reduces the Information-request traffic from a client that has not
received a response to its Information-request messages. received a response to its Information-request messages.
The format of the INF_MAX_RT option is: The format of the INF_MAX_RT option is:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_INF_MAX_RT | option-len | | OPTION_INF_MAX_RT | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| INF_MAX_RT value | | INF_MAX_RT value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 37: INF_MAX_RT Option Format Figure 37: INF_MAX_RT Option Format
option-code OPTION_INF_MAX_RT (83). option-code: OPTION_INF_MAX_RT (83).
option-len 4. option-len: 4.
INF_MAX_RT value Overriding value for INF_MAX_RT in seconds; INF_MAX_RT value: Overriding value for INF_MAX_RT in seconds; MUST
MUST be in this range: 60 <= "value" <= 86400 be in this range: 60 <= "value" <= 86400 (1 day). A 4-octet field
(1 day). A 4-octet field containing an containing an unsigned integer.
unsigned integer.
A DHCP client MUST include the INF_MAX_RT option code in any Option A DHCP client MUST include the INF_MAX_RT option code in any Option
Request option (see Section 21.7) it sends in an Information-request Request option (see Section 21.7) it sends in an Information-request
message. message.
The DHCP server MAY include the INF_MAX_RT option in any response it The DHCP server MAY include the INF_MAX_RT option in any response it
sends to a client that has included the INF_MAX_RT option code in an sends to a client that has included the INF_MAX_RT option code in an
Option Request option. The INF_MAX_RT option is a top-level option Option Request option. The INF_MAX_RT option is a top-level option
in the message to the client. in the message to the client.
skipping to change at page 121, line 29 skipping to change at line 5557
If a DHCP client receives a message containing an INF_MAX_RT option If a DHCP client receives a message containing an INF_MAX_RT option
that has a valid value for INF_MAX_RT, the client MUST set its that has a valid value for INF_MAX_RT, the client MUST set its
internal INF_MAX_RT parameter to the value contained in the internal INF_MAX_RT parameter to the value contained in the
INF_MAX_RT option. This value of INF_MAX_RT is then used by the INF_MAX_RT option. This value of INF_MAX_RT is then used by the
retransmission mechanism defined in Sections 15 and 18.2.6. retransmission mechanism defined in Sections 15 and 18.2.6.
An updated INF_MAX_RT value applies only to the network interface on An updated INF_MAX_RT value applies only to the network interface on
which the client received the INF_MAX_RT option. which the client received the INF_MAX_RT option.
22. Implementation status 22. Security Considerations
NOTE TO RFC EDITOR: Please remove this section before publication.
It is intended for the IESG evaluation.
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in RFC 7942.
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation
here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.
According to RFC 7942, "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".
The DHCPv6 protocol was originally published as RFC 3315 in July
2003. Many extensions were defined and RFC 8415 was published in
November 2018. The protocol was implemented by many vendors that
claim DHCPv6 compliance. It is sometimes difficult to determine
whether full compliance with 8415 is claimed.
The DHCPv6 protocol enjoys multiple interoperable implementations
from all sectors of industry. There are many open source and
proprietary implementations, both general software and hardware-
specific. The following implementations (listed alphabetically) are
known to support DHCPv6:
* Android (Google): In March 2023 (IETF'115) Google revealed it is
working on the PD client implementation for Android. Open source.
Maturity: prototype. Details are scarce, but it seems the
implementation will focus on PD functionality. Source:
https://datatracker.ietf.org/meeting/116/materials/slides-116-
v6ops-using-dhcp-pd-to-allocate-64-per-host-in-broadcast-networks-
00, slide 17.
* Cisco Prime Network Registrar: Cisco's software suite that
supports many protocols, including RFC8415 compliant server
functionality. Proprietary. Maturity: widely used. One of the
authors of this I-D was heavily involved in CPNR development.
Source: https://www.cisco.com/c/en/us/products/collateral/cloud-
systems-management/prime-network-registrar/datasheet-
c78-729989.html.
* dhcpcd: Client implementation. Works on many Linux and BSD
distributions, but seems to be the default client for various BSD
flavors. Open source (BSD). Maturity: widely used, in particular
on BSD systems. Source: https://github.com/NetworkConfiguration/
dhcpcd .
* dhcpd (ISC): Client, relay and server implementation, present in
most Linux and BSD distributions. Open source (Mozilla Public
License v2). The project is no longer developed, but the software
is still in wide use. Source: https://www.isc.org/dhcp/ .
* dibbler: Client, relay and server implementation. Limited
compatibility with RFC8415. Open source (GNU GPLv2). The project
is no longer developed, but the software is still in wide use.
The biggest known deployment is 16 million devices. One of the
authors of this I-D was the leading developer. Source:
https://klub.com.pl/dhcpv6/ .
* dnsmasq: Probably the most popular implementation in terms of
number of devices. Very popular among CPE and various home
appliances. Client and server implementation with some relay
capabilities. Open source (GPL v2 or v3). Source:
https://dnsmasq.org/ .
* EdgeMax (Ubiquiti): Proprietary implementation running on EdgeMax
hardware, home and small enterprise gateways and switches.
Focused on DHCPv6-PD. Source: https://help.ui.com/hc/en-us/
articles/115002531728-EdgeRouter-Beginners-Guide-to-EdgeRouter.
* EOS (Arista): Proprietary implementation for network switches,
routers and other networking hardware. RFC8415 support explicitly
stated. Server, client, relay implementation. Source:
https://www.arista.com/en/um-eos/eos-ipv6 .
* FreeRADIUS: RADIUS implementation that also provides DHCPv6 server
functionality. Open source.
* Huawei: Server, client and relay functionalities are available on
most routers and switches. Proprietary. Source:
https://support.huawei.com/hedex/
hdx.do?docid=EDOC1100247463&id=EN-US_TASK_0176372622, see
"Configuring Server/Relay/client/PD client" on the left panel.
* iOS (Apple): Client implementation running on Apple portable
devices (iPhones, iPads, etc.). Proprietary. The implementation
is widely used.
* IOS (Cisco): Server, relay, and client implementation that runs on
Cisco routers, switches and other networking hardware.
Proprietary. Widely used. Source:
https://community.cisco.com/t5/networking-knowledge-base/part-1-
implementing-dhcpv6-stateful-dhcpv6/ta-p/3145631 .
* Kea (ISC): Server implementation. Open source (Mozilla Public
License v2). It is a modern replacement for now retired isc-dhcp.
More than 500 users subscribed to the mailing list. One of the
authors of this I-D is the lead developer. Source:
https://kea.readthedocs.io/en/kea-2.4.0/arm/dhcp6-
srv.html#supported-dhcpv6-standards .
* JunOS (Juniper): Server, relay, and client implementation that
runs on Juniper routers, switches, and other networking hardware.
Proprietary. Widely used. Source:
https://www.juniper.net/documentation/us/en/software/junos/dhcp/
topics/topic-map/dhcpv6-server.html .
* macOS (Apple): Client implementation for Macs (laptops and
desktops). Proprietary. Widely used.
* odhcp6c (OpenWRT): Minimalistic client implementation intended for
embedded environment. Open source (GPL-2). Source:
https://github.com/openwrt/odhcp6c .
* RouterOS (Mikrotik): Server, relay, and client implementation
running on Mikrotik networking hardware (routers, switches, many
other appliances). Proprietary. Sources:
https://wiki.mikrotik.com/wiki/Manual:IPv6/DHCP_Client,
https://wiki.mikrotik.com/wiki/Manual:IPv6/DHCP_Server,
https://wiki.mikrotik.com/wiki/Manual:RouterOS6_news .
* ServPoET (Finepoint): Server implementation. Proprietary. One of
the authors of this I-D was the lead developer. Source:
https://finepoint.com/servpoet/ .
* udhcpc6 (busybox): Minimum footprint implementation, intended for
embedded devices. It used to be a separate project (udhcpc6), but
it is now part of the BusyBox project. Open source (GPL-v2).
Client implementation. Source: https://udhcp.busybox.net/
README.udhcpc .
* Unifi (Ubiquiti): Server, relay, and client implementation running
on UniFi hardware (routers, switches, firewalls). Proprietary.
Source: https://help.ui.com/hc/en-us/articles/115005868927-UniFi-
Gateway-Static-IPv6-and-DHCPv6-Prefix-Delegation.
* Windows (Microsoft): Microsoft Windows provides client
implementation, which is probably still the most popular OS on
desktops and laptops. The server version of Windows provides
DHCPv6 server implementation. Proprietary.
The DHCPv6 support is also mandated by some third party specs. For
example, all cable modems conformant to DOCSIS3.0 or later must
support DHCPv6 client functionality.
There are many large scale deployments that use DHCPv6. One of them
is Comcast's Xfinity. Authors are aware of many other large scale
country wide deployments, but due to signed Non-Disclosure Agreements
cannot list them.
University of New Hampshire's InterOperability Laboratory runs USGv6
Testing Program. Testing DHCPv6 compliance is one aspect of the
program.
While the original IPv6 Ready Logo testing involved the original
DHCPv6 specifications (primarily RFC3315, RFC3633), the large number
of tested and certified implementations supports the breadth and
depth of DHCPv6 implementations available and deployed in the
marketplace over the years that confirm the protocol specifications
are up to Internet Standard. See
https://www.ipv6ready.org/db/index.php/public/
search/?l=&c=&ds=&de=&pc=&ap=2&oem=&etc=D&fw=&vn=&do=1&o=6.-
23. Security Considerations
This section discusses security considerations that are not related This section discusses security considerations that are not related
to privacy. See Section 24 for a discussion dedicated to privacy. to privacy. See Section 23 for a discussion dedicated to privacy.
The threat to DHCP is inherently an insider threat (assuming a The threat to DHCP is inherently an insider threat (assuming a
properly configured network where DHCP ports are blocked on the properly configured network where DHCP ports are blocked on the
perimeter gateways of the enterprise). Regardless of the gateway perimeter gateways of the enterprise). Regardless of the gateway
configuration, however, the potential attacks by insiders and configuration, however, the potential attacks by insiders and
outsiders are the same. outsiders are the same.
DHCP lacks end-to-end encryption between clients and servers; thus, DHCP lacks end-to-end encryption between clients and servers; thus,
hijacking, tampering, and eavesdropping attacks are all possible as a hijacking, tampering, and eavesdropping attacks are all possible as a
result. Some network environments (discussed below) can be secured result. Some network environments (discussed below) can be secured
through various means to minimize these attacks. through various means to minimize these attacks.
The threat common to both the client and the server is the "resource- The threat common to both the client and the server is the "resource-
exhaustion" DoS attack. These attacks typically involve the exhaustion" DoS attack. Typically, these attacks involve the
exhaustion of available assigned addresses or delegatable prefixes, exhaustion of available assigned addresses or delegatable prefixes or
or the exhaustion of CPU or network bandwidth, and are present any the exhaustion of CPU or network bandwidth, and they are present any
time there is a shared resource. Some forms of these exhaustion time there is a shared resource. Some forms of these exhaustion
attacks can be partially mitigated by appropriate server policy, attacks can be partially mitigated by appropriate server policy,
e.g., limiting the maximum number of leases any one client can get, e.g., limiting the maximum number of leases any one client can get,
limiting the number of leases one client can decline, and limiting limiting the number of leases one client can decline, and limiting
number of messages a single client can transmit of a period of time. the number of messages a single client can transmit of a period of
time.
23.1. Client Security Considerations 22.1. Client Security Considerations
One attack specific to a DHCP client is the establishment of a One attack specific to a DHCP client is the establishment of a
malicious server with the intent of providing incorrect configuration malicious server with the intent of providing incorrect configuration
information to the client. The motivation for doing so may be to information to the client. The motivation for doing so may be to
mount a "man in the middle" attack that causes the client to mount a "man-in-the-middle" attack that causes the client to
communicate with a malicious server instead of a valid server for communicate with a malicious server instead of a valid server for
some service (such as DNS or NTP). The malicious server may also some service (such as DNS or NTP). The malicious server may also
mount a DoS attack through misconfiguration of the client; this mount a DoS attack through misconfiguration of the client; this
attack would cause all network communication from the client to fail. attack would cause all network communication from the client to fail.
A malicious DHCP server might cause a client to set its SOL_MAX_RT A malicious DHCP server might cause a client to set its SOL_MAX_RT
and INF_MAX_RT parameters to an unreasonably high value with the and INF_MAX_RT parameters to an unreasonably high value with the
SOL_MAX_RT (see Section 21.24) and INF_MAX_RT (see Section 21.25) SOL_MAX_RT (see Section 21.24) and INF_MAX_RT (see Section 21.25)
options; this may cause an undue delay in a client completing its options; this may cause an undue delay in a client completing its
DHCP protocol transaction in the case where no other valid response DHCP protocol transaction in the case where no other valid response
is received. Assuming that the client also receives a response from is received. Assuming that the client also receives a response from
a valid DHCP server, large values for SOL_MAX_RT and INF_MAX_RT will a valid DHCP server, large values for SOL_MAX_RT and INF_MAX_RT will
not have any effect. not have any effect.
Another threat to DHCP clients originates from mistakenly or Another threat to DHCP clients originates from mistakenly or
accidentally configured DHCP servers that answer DHCP client requests accidentally configured DHCP servers that answer DHCP client requests
with unintentionally incorrect configuration parameters. with unintentionally incorrect configuration parameters.
If a client implementation supports the reconfigure mechanism, also If a client implementation supports the reconfigure mechanism, see
see Section 23.3 below. Section 22.3.
23.2. Server Security Considerations 22.2. Server Security Considerations
The threat specific to a DHCP server is an invalid client The threat specific to a DHCP server is an invalid client
masquerading as a valid client. The motivation for this may be for masquerading as a valid client. The motivation for this may be for
theft of service, or to circumvent auditing for any number of theft of service or to circumvent auditing for any number of
nefarious purposes. nefarious purposes.
The messages exchanged between relay agents and servers may be used The messages exchanged between relay agents and servers may be used
to mount a man-in-the-middle or DoS attack. Communication between a to mount a man-in-the-middle or DoS attack. Communication between a
server and a relay agent, and communication between relay agents, can server and a relay agent, and communication between relay agents, can
be authenticated and encrypted through the use of IPsec, as described be authenticated and encrypted through the use of IPsec, as described
in [RFC8213]. in [RFC8213].
However, the use of manually configured pre-shared keys for IPsec However, the use of manually configured pre-shared keys for IPsec
between relay agents and servers does not defend against replayed between relay agents and servers does not defend against replayed
DHCP messages. Replayed messages can represent a DoS attack through DHCP messages. Replayed messages can represent a DoS attack through
exhaustion of processing resources but not through misconfiguration exhaustion of processing resources but not through misconfiguration
or exhaustion of other resources such as assignable addresses and or exhaustion of other resources such as assignable addresses and
delegatable prefixes. delegatable prefixes.
If a server implementation supports the reconfigure mechanism, also If a server implementation supports the reconfigure mechanism, see
see Section 23.3 below. Section 22.3.
23.3. Reconfigure Security Considerations 22.3. Reconfigure Security Considerations
RKAP, described in Section 20.4, provides protection against the use RKAP, described in Section 20.4, provides protection against the use
of a Reconfigure message by a malicious DHCP server to mount a DoS or of a Reconfigure message by a malicious DHCP server to mount a DoS or
man-in-the-middle attack on a client. This protocol can be man-in-the-middle attack on a client. This protocol can be
compromised by an attacker that can intercept the initial message in compromised by an attacker that can intercept the initial message in
which the DHCP server sends the key as plain text to the client. which the DHCP server sends the key as plain text to the client.
Because of the opportunity for attack through the Reconfigure Because of the opportunity for attack through the Reconfigure
message, a DHCP client MUST discard any Reconfigure message that does message, a DHCP client MUST discard any Reconfigure message that does
not include authentication or that does not pass the validation not include authentication or that does not pass the validation
skipping to change at page 127, line 25 skipping to change at line 5662
that response will only be received by servers to which DHCP messages that response will only be received by servers to which DHCP messages
are relayed, a malicious server could send a Reconfigure message to a are relayed, a malicious server could send a Reconfigure message to a
client, followed (after an appropriate delay) by a Reply message that client, followed (after an appropriate delay) by a Reply message that
would be accepted by the client. Thus, a malicious server that is would be accepted by the client. Thus, a malicious server that is
not on the network path between the client and the server may still not on the network path between the client and the server may still
be able to mount a Reconfigure attack on a client. The use of be able to mount a Reconfigure attack on a client. The use of
transaction IDs that are cryptographically sound and cannot easily be transaction IDs that are cryptographically sound and cannot easily be
predicted will also reduce the probability that such an attack will predicted will also reduce the probability that such an attack will
be successful. be successful.
23.4. Mitigation Considerations 22.4. Mitigation Considerations
Various network environments also offer levels of security if Various network environments also offer levels of security if
deployed as described below. deployed as described below.
* In enterprise and factory networks, use of authentication per * In enterprise and factory networks, use of authentication per
[IEEE-802.1x] can prevent unknown or untrusted clients from [IEEE-802.1x] can prevent unknown or untrusted clients from
connecting to the network. However, this does not necessarily connecting to the network. However, this does not necessarily
assure that the connected client will be a good DHCP or network assure that the connected client will be a good DHCP or network
actor. actor.
skipping to change at page 127, line 50 skipping to change at line 5687
fe02::1:2) are only forwarded to the DHCP server's (or relay's) fe02::1:2) are only forwarded to the DHCP server's (or relay's)
switch port -- not all ports. Also, the server's (or relay's) switch port -- not all ports. Also, the server's (or relay's)
unicast replies are only delivered to the target client's port -- unicast replies are only delivered to the target client's port --
not all ports. not all ports.
* In public networks (such as a Wi-Fi network in a coffee shop or * In public networks (such as a Wi-Fi network in a coffee shop or
airport), it is possible for others within radio range to snoop airport), it is possible for others within radio range to snoop
DHCP and other traffic. But in these environments, there is very DHCP and other traffic. But in these environments, there is very
little if anything that can be learned from the DHCP traffic little if anything that can be learned from the DHCP traffic
itself (either from client to server or from server to client) if itself (either from client to server or from server to client) if
the privacy considerations provided in Section 24 are followed. the privacy considerations provided in Section 23 are followed.
Even for devices that do not follow the privacy considerations, Even for devices that do not follow the privacy considerations,
there is little that can be learned that would not be available there is little that can be learned that would not be available
from subsequent communications anyway (such as the device's Media from subsequent communications anyway (such as the device's Media
Access Control (MAC) address). Also, because all clients will Access Control (MAC) address). Also, because all clients will
typically receive similar configuration details, a bad actor that typically receive similar configuration details, a bad actor that
initiates a DHCP request itself can learn much of such initiates a DHCP request itself can learn much of such
information. As mentioned above, one threat is that the RKAP key information. As mentioned above, one threat is that the RKAP key
for a client can be learned (if the initial for a client can be learned (if the initial
Solicit/Advertise/Request/Reply exchange is monitored) and trigger Solicit/Advertise/Request/Reply exchange is monitored) and trigger
a premature reconfiguration, but this is relatively easily a premature reconfiguration, but this is relatively easily
prevented by disallowing direct client-to-client communication on prevented by disallowing direct client-to-client communication on
these networks or using [RFC7610] and [RFC7513]. these networks or using [RFC7610] and [RFC7513].
Many of the attacks by rogue servers can be mitigated by making use Many of the attacks by rogue servers can be mitigated by making use
of the mechanisms described in [RFC7610] and [RFC7513]. of the mechanisms described in [RFC7610] and [RFC7513].
24. Privacy Considerations 23. Privacy Considerations
For an extended discussion about privacy considerations for the For an extended discussion about privacy considerations for the
client, see [RFC7824]: client, see [RFC7824]:
* In particular, its Section 3 discusses various identifiers that * In particular, Section 3 of [RFC7824] discusses various
could be misused to track the client. identifiers that could be misused to track the client.
* Its Section 4 discusses existing mechanisms that may have an * Section 4 of [RFC7824] discusses existing mechanisms that may have
impact on a client's privacy. an impact on a client's privacy.
* Finally, its Section 5 discusses potential attack vectors. * Finally, Section 5 of [RFC7824] discusses potential attack
vectors.
For recommendations regarding how to address or mitigate those For recommendations regarding how to address or mitigate those
issues, see [RFC7844]. issues, see [RFC7844].
This specification does not define any allocation strategies for This specification does not define any allocation strategies for
servers. Implementers are expected to develop their own algorithm servers. Implementers are expected to develop their own algorithm
for the server to choose a resource out of the available pool. for the server to choose a resource out of the available pool.
Several possible allocation strategies are mentioned in Section 4.3 Several possible allocation strategies are mentioned in Section 4.3
of [RFC7824]. Please keep in mind that the list in [RFC7824] is not of [RFC7824]. Please keep in mind that the list in [RFC7824] is not
exhaustive; there are certainly other possible strategies. Readers exhaustive; there are certainly other possible strategies. Readers
are also encouraged to read [RFC7707] -- in particular, its are also encouraged to read [RFC7707] -- in particular, Section 4.1.2
Section 4.1.2, which discusses the problems with certain allocation of [RFC7707], which discusses the problems with certain allocation
strategies. strategies.
25. IANA Considerations 24. IANA Considerations
This document does not define any new DHCP name spaces or This document does not define any new DHCP name spaces or
definitions. definitions.
The publication of this document does not change the assignment rules The publication of this document does not change the assignment rules
for new values for message types, option codes, DUID types, or status for new values for message types, option codes, DUID types, or status
codes. codes.
The list of assigned values used in DHCPv6 is available at The list of assigned values used in DHCPv6 is available at
<https://www.iana.org/assignments/dhcpv6-parameters>. <https://www.iana.org/assignments/dhcpv6-parameters>.
IANA is requested to update all references to [RFC8415] to this IANA has updated all references to [RFC8415] to this document at
document at <https://www.iana.org/assignments/dhcpv6-parameters>. <https://www.iana.org/assignments/dhcpv6-parameters>.
IANA is requested to add a new column "Status" to all registries on IANA has added a new column "Status" to all registries on the DHCPv6
the DHCPv6 parameters page at <https://www.iana.org/assignments/ parameters page at <https://www.iana.org/assignments/
dhcpv6-parameters> and leave each entry blank except as indicated dhcpv6-parameters> and has left each entry blank except as indicated
below: below:
* In the Option Code registry, set the "Status" column value to * In the "Option Codes" registry, the "Status" column value has been
"Obsolete" for the IA_TA (option code 4) and UNICAST (option code set to "Obsolete" for the IA_TA (option code 4) and UNICAST
12) rows. (option code 12) rows.
* In the Status Codes registry, set the "Status" column value to * In the "Status Codes" registry, the "Status" column value has been
"Obsolete" for the UseMulticast (status code 5) row. set to "Obsolete" for the UseMulticast (status code 5) row.
IANA is requested to update other references to [RFC8415] with IANA has updated other references to [RFC8415] with references to
references to this document at: this document at:
* https://www.iana.org/assignments/auth-namespaces (four entries) * <https://www.iana.org/assignments/auth-namespaces> (four entries)
* https://www.iana.org/assignments/bootp-dhcp-parameters (two * <https://www.iana.org/assignments/bootp-dhcp-parameters> (two
entries) entries)
* https://www.iana.org/assignments/ipv6-multicast-addresses (two * <https://www.iana.org/assignments/ipv6-multicast-addresses> (two
entries) entries)
* https://www.iana.org/assignments/service-names-port-numbers (two * <https://www.iana.org/assignments/service-names-port-numbers> (two
entries; UDP ports 546 and 547) entries; UDP ports 546 and 547)
26. References 25. References
26.1. Normative References 25.1. Normative References
[BCP145] Best Current Practice 145, [BCP145] Best Current Practice 145,
<https://www.rfc-editor.org/info/bcp145>. <https://www.rfc-editor.org/info/bcp145>.
At the time of writing, this BCP comprises the following: At the time of writing, this BCP comprises the following:
Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085, Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
March 2017, <https://www.rfc-editor.org/info/rfc8085>. March 2017, <https://www.rfc-editor.org/info/rfc8085>.
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
skipping to change at page 131, line 15 skipping to change at line 5845
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200, (IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017, DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>. <https://www.rfc-editor.org/info/rfc8200>.
[RFC8213] Volz, B. and Y. Pal, "Security of Messages Exchanged [RFC8213] Volz, B. and Y. Pal, "Security of Messages Exchanged
between Servers and Relay Agents", RFC 8213, between Servers and Relay Agents", RFC 8213,
DOI 10.17487/RFC8213, August 2017, DOI 10.17487/RFC8213, August 2017,
<https://www.rfc-editor.org/info/rfc8213>. <https://www.rfc-editor.org/info/rfc8213>.
26.2. Informative References 25.2. Informative References
[Err6159] RFC Errata, Erratum ID 6159, RFC 8415,
<https://www.rfc-editor.org/errata/eid1912>.
[Err6183] RFC Errata, Erratum ID 6183, RFC 8415,
<https://www.rfc-editor.org/errata/eid1912>.
[Err6269] RFC Errata, Erratum ID 6269, RFC 8415,
<https://www.rfc-editor.org/errata/eid1912>.
[IANA-HARDWARE-TYPES] [IANA-HARDWARE-TYPES]
IANA, "Hardware Types", IANA, "Hardware Types",
<https://www.iana.org/assignments/arp-parameters>. <https://www.iana.org/assignments/arp-parameters>.
[IANA-OPTION-DETAILS] [IANA-OPTION-DETAILS]
IANA, "Option Codes", IANA, "Option Codes",
<https://www.iana.org/assignments/dhcpv6-parameters>. <https://www.iana.org/assignments/dhcpv6-parameters>.
[IANA-PEN] IANA, "Private Enterprise Numbers", [IANA-PEN] IANA, "Private Enterprise Numbers",
<https://www.iana.org/assignments/enterprise-numbers>. <https://www.iana.org/assignments/enterprise-numbers>.
[IANA-RESERVED-IID] [IANA-RESERVED-IID]
IANA, "Reserved IPv6 Interface Identifiers", IANA, "Reserved IPv6 Interface Identifiers",
<https://www.iana.org/assignments/ipv6-interface-ids>. <https://www.iana.org/assignments/ipv6-interface-ids>.
[IEEE-802.1x] [IEEE-802.1x]
IEEE, "IEEE Standard for Local and metropolitan area IEEE, "IEEE Standard for Local and metropolitan area
networks--Port-Based Network Access Control", IEEE 802.1X- networks--Port-Based Network Access Control", IEEE 802.1X-
2010, DOI 10.1109/IEEESTD.2010.5409813, 2010, DOI 10.1109/IEEESTD.2010.5409813, February 2010,
<https://ieeexplore.ieee.org/servlet/ <https://ieeexplore.ieee.org/document/5409813>.
opac?punumber=5409757>.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", [RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, DOI 10.17487/RFC2131, March 1997, RFC 2131, DOI 10.17487/RFC2131, March 1997,
<https://www.rfc-editor.org/info/rfc2131>. <https://www.rfc-editor.org/info/rfc2131>.
[RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet
Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998, Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998,
<https://www.rfc-editor.org/info/rfc2464>. <https://www.rfc-editor.org/info/rfc2464>.
[RFC3162] Aboba, B., Zorn, G., and D. Mitton, "RADIUS and IPv6", [RFC3162] Aboba, B., Zorn, G., and D. Mitton, "RADIUS and IPv6",
skipping to change at page 136, line 14 skipping to change at line 6090
[RFC9243] Farrer, I., Ed., "A YANG Data Model for DHCPv6 [RFC9243] Farrer, I., Ed., "A YANG Data Model for DHCPv6
Configuration", RFC 9243, DOI 10.17487/RFC9243, June 2022, Configuration", RFC 9243, DOI 10.17487/RFC9243, June 2022,
<https://www.rfc-editor.org/info/rfc9243>. <https://www.rfc-editor.org/info/rfc9243>.
[RFC9686] Kumari, W., Krishnan, S., Asati, R., Colitti, L., Linkova, [RFC9686] Kumari, W., Krishnan, S., Asati, R., Colitti, L., Linkova,
J., and S. Jiang, "Registering Self-Generated IPv6 J., and S. Jiang, "Registering Self-Generated IPv6
Addresses Using DHCPv6", RFC 9686, DOI 10.17487/RFC9686, Addresses Using DHCPv6", RFC 9686, DOI 10.17487/RFC9686,
December 2024, <https://www.rfc-editor.org/info/rfc9686>. December 2024, <https://www.rfc-editor.org/info/rfc9686>.
[TR-187] Broadband Forum, "TR-187 - IPv6 for PPP Broadband Access", [TR-187] Broadband Forum, "IPv6 for PPP Broadband Access", TR-187,
February 2013, <https://www.broadband- Issue: 2, February 2013,
forum.org/technical/download/TR-187_Issue-2.pdf>. <https://www.broadband-forum.org/pdfs/tr-187-2-0-0.pdf>.
Appendix A. Summary of Changes Appendix A. Summary of Changes from RFC 8415
This appendix provides a summary of the changes made from RFC8415: This appendix provides a summary of the differences between this
document and [RFC8415]:
1. The following mechanisms were obsoleted. These were not widely 1. The following mechanisms were obsoleted. These were not widely
deployed while adding complexity to client and server deployed while adding complexity to client and server
implementations. Legacy implementations MAY support them, but implementations. Legacy implementations MAY support them, but
implementations conformant to this document MUST NOT rely on implementations conformant to this document MUST NOT rely on
them. Obsoleting these features does not cause any them. Obsoleting these features does not cause any
interoperatability issues when mixing updated and non-updated interoperability issues when mixing updated and non-updated
clients, relay agents, and servers as these mechanisms were clients, relay agents, and servers as these mechanisms were
"optional". "optional".
IA_TA option. The Identity Association for Temporary Addresses * IA_TA option. The Identity Association for Temporary
option has been obsoleted. A client that needs a short-term / Addresses option has been obsoleted. A client that needs a
special purpose address can use a new IA_NA binding to request short-term / special purpose address can use a new IA_NA
an address and release it when finished with it. binding to request an address and release it when finished
with it.
UNICAST option. The Server Unicast option has been obsoleted. * UNICAST option. The Server Unicast option has been obsoleted.
Use of this was rarely practical as typically relay agents Use of this was rarely practical as typically relay agents
between the client and server need to glean information from between the client and server need to glean information from
the communication and cannot be bypassed. the communication and cannot be bypassed.
UseMulticast status code. The UseMulticast status code has been * UseMulticast status code. The UseMulticast status code has
obsoleted. Clients will always multicast messages (as Server been obsoleted. Clients will always multicast messages (as
Unicast option has been obsoleted) and servers will no longer Server Unicast option has been obsoleted) and servers will no
check for unicast traffic. longer check for unicast traffic.
2. The following errata for RFC 8415 were incorporated: erratum IDs 2. The following errata reports for [RFC8415] were incorporated:
6159, 6269 and 6183. Note that erratum ID 6269 was no longer [Err6159] [Err6269], [Err6183]. Note that EID 6269 was no longer
applicable after the Server Unicast Option was obsoleted. Note applicable after the Server Unicast Option was obsoleted. Note
that erratum 6159 is also no longer applicable now that temporary that EID 6159 was also no longer applicable as temporary
addresses have been obsoleted. Indeed, the section (6.5) that addresses have been obsoleted. Indeed, the text that EID 6159
erratum 6159 corrects has been deleted. corrects has been deleted.
3. A reference to RFC 7943 was added to Section 13.1 as it documents 3. A reference to [RFC7943] was added to Section 13.1 as it
a method that might be used to generate addresses and was documents a method that might be used to generate addresses and
inadvertently missed when compiling RFC 8415. was inadvertently missed when compiling [RFC8415].
4. Clarified the UDP ports used by clients, servers, and relay 4. Clarified the UDP ports used by clients, servers, and relay
agents (Section 7.2). agents (Section 7.2).
5. Several additional RFCs have been referenced and editorial and 5. Several additional RFCs have been referenced and editorial and
reviews comments incorporated. reviews comments incorporated.
Appendix B. Appearance of Options in Message Types Appendix B. Appearance of Options in Message Types
The following tables indicate with a "*" the options that are allowed The following tables indicate with a "*" the options that are allowed
in each DHCP message type. in each DHCP message type.
These tables are informational. If they conflict with text earlier These tables are informational. If they conflict with text earlier
in this document, that text should be considered authoritative. in this document, that text should be considered authoritative.
Client Server Elap. Relay +=========+========+========+=====+=====+===+====+=====+=====+=====+
ID ID IA_NA IA_PD ORO Pref Time Msg. Auth. | | Client | Server |IA_NA|IA_PD|ORO|Pref|Elap.|Relay|Auth.|
Solicit * * * * * | | ID | ID | | | | |Time |Msg. | |
Advert. * * * * * +=========+========+========+=====+=====+===+====+=====+=====+=====+
Request * * * * * * | Solicit | * | | * | * | * | | * | | |
Confirm * * * +=========+--------+--------+-----+-----+---+----+-----+-----+-----+
Renew * * * * * * | Advert. | * | * | * | * | | * | | | |
Rebind * * * * * +=========+--------+--------+-----+-----+---+----+-----+-----+-----+
Decline * * * * * | Request | * | * | * | * | * | | * | | |
Release * * * * * +=========+--------+--------+-----+-----+---+----+-----+-----+-----+
Reply * * * * * | Confirm | * | | * | | | | * | | |
Reconf. * * * +=========+--------+--------+-----+-----+---+----+-----+-----+-----+
Inform. * (see note) * * | Renew | * | * | * | * | * | * | * | | |
R-forw. * +=========+--------+--------+-----+-----+---+----+-----+-----+-----+
R-repl. * | Rebind | * | | * | * | * | | * | | |
+=========+--------+--------+-----+-----+---+----+-----+-----+-----+
| Decline | * | * | * | * | | | * | | |
+=========+--------+--------+-----+-----+---+----+-----+-----+-----+
| Release | * | * | * | * | | | * | | |
+=========+--------+--------+-----+-----+---+----+-----+-----+-----+
| Reply | * | * | * | * | | | | | * |
+=========+--------+--------+-----+-----+---+----+-----+-----+-----+
| Reconf | * | * | | | | | | | * |
+=========+--------+--------+-----+-----+---+----+-----+-----+-----+
| Inform. | * | (see | | | * | | * | | |
| | | note) | | | | | | | |
+=========+--------+--------+-----+-----+---+----+-----+-----+-----+
| R-forw. | | | | | | | | | * |
+=========+--------+--------+-----+-----+---+----+-----+-----+-----+
| R-repl. | | | | | | | | | * |
+=========+--------+--------+-----+-----+---+----+-----+-----+-----+
Table 4
NOTE: The Server Identifier option (see Section 21.3) is only NOTE: The Server Identifier option (see Section 21.3) is only
included in Information-request messages that are sent in response to included in Information-request messages that are sent in response to
a Reconfigure (see Section 18.2.6). a Reconfigure (see Section 18.2.6).
Info +=======+======+=====+=====+======+======+======+======+======+=====+
Status Rap. User Vendor Vendor Inter. Recon. Recon. Refresh | |Status|Rap. |User |Vendor|Vendor|Inter.|Recon.|Recon.|Info |
Code Comm. Class Class Spec. ID Msg. Accept Time | |Code |Comm.|Class|Class |Spec. |ID |Msg. |Accept|Refr.|
Solicit * * * * * | | | | | | | | | |Time |
Advert. * * * * * +=======+======+=====+=====+======+======+======+======+======+=====+
Request * * * * |Solicit| | * | * | * | * | | | * | |
Confirm * * * +=======+------+-----+-----+------+------+------+------+------+-----+
Renew * * * * |Advert.| * | | * | * | * | | | * | |
Rebind * * * * +=======+------+-----+-----+------+------+------+------+------+-----+
Decline * * * |Request| | | * | * | * | | | * | |
Release * * * +=======+------+-----+-----+------+------+------+------+------+-----+
Reply * * * * * * * |Confirm| | | * | * | * | | | | |
Reconf. * +=======+------+-----+-----+------+------+------+------+------+-----+
Inform. * * * * |Renew | | | * | * | * | | | * | |
R-forw. * * +=======+------+-----+-----+------+------+------+------+------+-----+
R-repl. * * |Rebind | | | * | * | * | | | * | |
+=======+------+-----+-----+------+------+------+------+------+-----+
|Decline| | | * | * | * | | | | |
+=======+------+-----+-----+------+------+------+------+------+-----+
|Release| | | * | * | * | | | | |
+=======+------+-----+-----+------+------+------+------+------+-----+
|Reply | * | * | * | * | * | | | * | * |
+=======+------+-----+-----+------+------+------+------+------+-----+
|Reconf.| | | | | | | * | | |
+=======+------+-----+-----+------+------+------+------+------+-----+
|Inform.| | | * | * | * | | | * | |
+=======+------+-----+-----+------+------+------+------+------+-----+
|R-forw.| | | | | * | * | | | |
+=======+------+-----+-----+------+------+------+------+------+-----+
|R-repl.| | | | | * | * | | | |
+=======+------+-----+-----+------+------+------+------+------+-----+
SOL_MAX_RT INF_MAX_RT Table 5
Solicit
Advert. * +=========+============+============+
Request | | SOL_MAX_RT | INF_MAX_RT |
Confirm +=========+============+============+
Renew | Solicit | | |
Rebind +---------+------------+------------+
Decline | Advert. | * | |
Release +---------+------------+------------+
Reply * * | Request | | |
Reconf. +---------+------------+------------+
Inform. | Confirm | | |
R-forw. +---------+------------+------------+
R-repl. | Renew | | |
+---------+------------+------------+
| Rebind | | |
+---------+------------+------------+
| Decline | | |
+---------+------------+------------+
| Release | | |
+---------+------------+------------+
| Reply | * | * |
+---------+------------+------------+
| Reconf. | | |
+---------+------------+------------+
| Inform. | | |
+---------+------------+------------+
| R-forw. | | |
+---------+------------+------------+
| R-repl. | | |
+---------+------------+------------+
Table 6
Appendix C. Appearance of Options in the "options" Field of DHCP Appendix C. Appearance of Options in the "options" Field of DHCP
Options Options
The following table indicates with a "*" where options defined in The following table indicates with a "*" where options defined in
this document can appear as top-level options or can be encapsulated this document can appear as top-level options or can be encapsulated
in other options defined in this document. Other RFCs may define in other options defined in this document. Other RFCs may define
additional situations where options defined in this document are additional situations where options defined in this document are
encapsulated in other options. encapsulated in other options.
This table is informational. If it conflicts with text earlier in This table is informational. If it conflicts with text earlier in
this document, that text should be considered authoritative. this document, that text should be considered authoritative.
Top- RELAY- RELAY- +============+=====+=====+======+=====+==========+========+========+
Level IA_NA IAADDR IA_PD IAPREFIX FORW REPL | |Top- |IA_NA|IAADDR|IA_PD| IAPREFIX | RELAY- | RELAY- |
Client ID * | |Level| | | | | FORW | REPL |
Server ID * +============+=====+=====+======+=====+==========+========+========+
IA_NA * | Client ID | * | | | | | | |
IAADDR * +============+-----+-----+------+-----+----------+--------+--------+
IA_PD * | Server ID | * | | | | | | |
IAPREFIX * +============+-----+-----+------+-----+----------+--------+--------+
ORO * | IA_NA | * | | | | | | |
Preference * +============+-----+-----+------+-----+----------+--------+--------+
Elapsed Time * | IAADDR | | * | | | | | |
Relay Message * * +============+-----+-----+------+-----+----------+--------+--------+
Authentic. * | IA_PD | * | | | | | | |
Status Code * * * +============+-----+-----+------+-----+----------+--------+--------+
Rapid Comm. * | IAPREFIX | | | | * | | | |
User Class * +============+-----+-----+------+-----+----------+--------+--------+
Vendor Class * | ORO | * | | | | | | |
Vendor Info. * * * +============+-----+-----+------+-----+----------+--------+--------+
Interf. ID * * | Preference | * | | | | | | |
Reconf. MSG. * +============+-----+-----+------+-----+----------+--------+--------+
Reconf. Accept * | Elapsed | * | | | | | | |
Info Refresh Time * | Time | | | | | | | |
SOL_MAX_RT * +============+-----+-----+------+-----+----------+--------+--------+
INF_MAX_RT * | Relay | | | | | | * | * |
| Message | | | | | | | |
+============+-----+-----+------+-----+----------+--------+--------+
| Authentic. | * | | | | | | |
+============+-----+-----+------+-----+----------+--------+--------+
| Status | * | * | | * | | | |
| Code | | | | | | | |
+============+-----+-----+------+-----+----------+--------+--------+
| Rapid | * | | | | | | |
| Comm. | | | | | | | |
+============+-----+-----+------+-----+----------+--------+--------+
| User Class | * | | | | | | |
+============+-----+-----+------+-----+----------+--------+--------+
| Vendor | * | | | | | | |
| Class | | | | | | | |
+============+-----+-----+------+-----+----------+--------+--------+
| Vendor | * | | | | | * | * |
| Info. | | | | | | | |
+============+-----+-----+------+-----+----------+--------+--------+
| Interf. | | | | | | * | * |
| ID | | | | | | | |
+============+-----+-----+------+-----+----------+--------+--------+
| Reconf. | * | | | | | | |
| MSG. | | | | | | | |
+============+-----+-----+------+-----+----------+--------+--------+
| Reconf. | * | | | | | | |
| Accept | | | | | | | |
+============+-----+-----+------+-----+----------+--------+--------+
| Info | * | | | | | | |
| Refresh | | | | | | | |
| Time | | | | | | | |
+============+-----+-----+------+-----+----------+--------+--------+
| SOL_MAX_RT | * | | | | | | |
+============+-----+-----+------+-----+----------+--------+--------+
| INF_MAX_RT | * | | | | | | |
+============+-----+-----+------+-----+----------+--------+--------+
Table 7
Notes: Options asterisked in the "Top-Level" column appear in the Notes: Options asterisked in the "Top-Level" column appear in the
"options" field of client messages (see Section 8). Options "options" field of client messages (see Section 8). Options
asterisked in the "RELAY-FORW" and "RELAY-REPL" columns appear in the asterisked in the "RELAY-FORW" and "RELAY-REPL" columns appear in the
"options" field of the Relay-forward and Relay-reply messages (see "options" field of the Relay-forward and Relay-reply messages (see
Section 9). Section 9).
Acknowledgments Acknowledgments
This document is merely a refinement of earlier work as described in This document is merely a refinement of earlier work as described in
RFC 8415. [RFC8415].
A number of additional people have contributed to identifying issues A number of additional people have contributed to identifying issues
with RFC 8415, including Fernando Gont, Felix Hamme, Rene Engel, Esko with [RFC8415] including Fernando Gont, Felix Hamme, Rene Engel, Esko
Dijk, Jen Linkova, Tomoyuki Sahara, and Ted Lemon. Dijk, Jen Linkova, Tomoyuki Sahara, and Ted Lemon.
We thank the thorough and thoughtful reviewers during the IETF We thank the thorough and thoughtful reviewers during the IETF
process, especially Mohamed Boucadair, Tim Chown, Roman Danyliw, process, especially Mohamed Boucadair, Tim Chown, Roman Danyliw,
Tatuya Jinmei, Jim Read, Ketan Talaulikar, Eric Vyncke, Dave Worley. Tatuya Jinmei, Jim Read, Ketan Talaulikar, Éric Vyncke, and Dave
We also thank the DHC working group members for their reviews of this Worley. We also thank the DHC WG members for their reviews of this
updated document. updated document.
And, special thanks to Suresh Krishnan for shepherding this document And special thanks to Suresh Krishnan for shepherding this document
through the IETF process. through the IETF process.
Authors' Addresses Authors' Addresses
Tomek Mrugalski Tomek Mrugalski
Internet Systems Consortium, Inc. Internet Systems Consortium, Inc.
PO Box 360 PO Box 360
Newmarket, NH 03857 Newmarket, NH 03857
United States of America United States of America
Email: tomasz.mrugalski@gmail.com Email: tomasz.mrugalski@gmail.com
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