rfc9952v1.md		rfc9952.md
	---		---
	title: "The Application-Layer Protocol Negotiation (ALPN) ID Specification for the Co		title: "Application-Layer Protocol Negotiation (ALPN) ID for CoAP over DTLS"
	nstrained Application Protocol (CoAP) over DTLS"		abbrev: "ALPN ID for CoAP over DTLS"
	abbrev: "CoRE ALPN"
	category: info		category: info
	docname: draft-ietf-core-coap-dtls-alpn-05		docname: draft-ietf-core-coap-dtls-alpn-05
	submissiontype: IETF		submissiontype: IETF
	number: 9952		number: 9952
	updates:		updates:
	obsoletes:		obsoletes:
	consensus: true		consensus: true
	ipr: trust200902		ipr: trust200902
	pi: [toc, symrefs, sortrefs]		pi: [toc, symrefs, sortrefs]
	skipping to change at line 91 ¶		skipping to change at line 91 ¶
	-		-
	fullname: Matthias Wählisch		fullname: Matthias Wählisch
	RFC4944: 6lo		RFC4944: 6lo
	--- abstract		--- abstract
	<!-- [rfced] FYI - We updated [I-D.ietf-core-dns-over-coap] to [PRE-RFC9953]		<!-- [rfced] FYI - We updated [I-D.ietf-core-dns-over-coap] to [PRE-RFC9953]
	for now. We will make the final updates in RFCXML (i.e., remove "PRE-").		for now. We will make the final updates in RFCXML (i.e., remove "PRE-").
	-->		-->
	<!--[rfced] Author Names
	a) Thomas, we note "T. C. Schmidt" in the document header; however, the
	majority of past RFCs have used "T. Schmidt". Which form do you prefer?
	b) Martine, please confirm if you prefer "M. S. Lenders" or "M. Lenders"
	in the document header.
	<!-- [I-D.ietf-core-dns-over-coap] - RFC 9953		<!-- [I-D.ietf-core-dns-over-coap] - RFC 9953
	draft-ietf-core-dns-over-coap-20		draft-ietf-core-dns-over-coap-20
	Companion document (C554)		Companion document (C554)
	-->		-->
	<!--[rfced] Document Title		<!--[rfced] Document Title
	a) Please note that the document title has been updated as follows.		a) Please note that the document title has been updated as follows.
	Abbreviations have been expanded per Section 3.6 of RFC 7322 ("RFC Style		Abbreviations have been expanded per Section 3.6 of RFC 7322 ("RFC Style
	Guide").		Guide").
	skipping to change at line 124 ¶		skipping to change at line 115 ¶
	Original (document title):		Original (document title):
	ALPN ID Specification for CoAP over DTLS		ALPN ID Specification for CoAP over DTLS
	Current:		Current:
	The Application-Layer Protocol Negotiation (ALPN) ID Specification for		The Application-Layer Protocol Negotiation (ALPN) ID Specification for
	the Constrained Application Protocol (CoAP) over DTLS		the Constrained Application Protocol (CoAP) over DTLS
	Perhaps:		Perhaps:
	Application-Layer Protocol Negotiation (ALPN) ID for		Application-Layer Protocol Negotiation (ALPN) ID for
	the Constrained Application Protocol (CoAP) over DTLS		the Constrained Application Protocol (CoAP) over DTLS
	b) For the short title that spans the header of the PDF file, should "CoRE
	ALPN" be updated to "ALPN ID for CoAP over DTLS" to more closely match the
	document title?
	Original (short title):
	CoRE ALPN
	Perhaps:
	ALPN ID for CoAP over DTLS
	<!-- [rfced] Abstract: Should the abstract mention DTLS?
	Original:
	This document specifies an Application-Layer Protocol Negotiation
	(ALPN) ID for transport-layer-secured Constrained Application
	Protocol (CoAP) services.
	Perhaps (similar to text in the Introduction):
	This document specifies an Application-Layer Protocol Negotiation
	(ALPN) ID for Constrained Application
	Protocol (CoAP) services that are secured by DTLS.
	<!-- [rfced] Introduction: We updated "by transport layer security using DTLS"
	to "by TLS using DTLS" here. Would further updating as shown below improve
	this sentence?
	Original:
	This document
	specifies an ALPN ID for CoAP services that are secured by transport
	layer security using DTLS.
	Current:
	This document
	specifies an ALPN ID for CoAP services that are secured by TLS
	using DTLS.
	Perhaps:
	This document
	specifies an ALPN ID for CoAP services that are secured
	by DTLS.
	-->		-->
	This document specifies an Application-Layer Protocol Negotiation (ALPN) ID for		This document specifies an Application-Layer Protocol Negotiation (ALPN) ID for
	transport-layer-secured Constrained Application Protocol (CoAP) services.		Constrained Application Protocol (CoAP) services that are secured by DTLS.
	--- middle		--- middle
	# Introduction		# Introduction
	Application-Layer Protocol Negotiation (ALPN) enables communicating parties to agree on an application-layer protocol during a Transport Layer Security (TLS) handshake us ing an ALPN ID {{-alpn}}.		Application-Layer Protocol Negotiation (ALPN) enables communicating parties to agree on an application-layer protocol during a Transport Layer Security (TLS) handshake us ing an ALPN ID {{-alpn}}.
	This ALPN ID can be discovered for services as part of Service Bindings (SVCBs) via t he DNS, using SVCB resource records with the "alpn" Service Parameter Keys {{-svcb}}.		This ALPN ID can be discovered for services as part of Service Bindings (SVCBs) via t he DNS, using SVCB resource records with the "alpn" Service Parameter Keys {{-svcb}}.
	As an example, applications that use the Constrained Application Protocol (CoAP) {{-c oap}} can obtain this information as part of the discovery of DNS over CoAP (DoC) ser vers (see {{Section 3.2 of -doc}}) that deploy TLS 1.3 {{-tls13}} as well as Datagram Transport Layer Security (DTLS) 1.2 or 1.3 {{-dtls12}} {{-dtls13}} to secure their m essages.		As an example, applications that use the Constrained Application Protocol (CoAP) {{-c oap}} can obtain this information as part of the discovery of DNS over CoAP (DoC) ser vers (see {{Section 3.2 of -doc}}) that deploy TLS 1.3 {{-tls13}} as well as Datagram Transport Layer Security (DTLS) 1.2 or 1.3 {{-dtls12}} {{-dtls13}} to secure their m essages.
	This document specifies an ALPN ID for CoAP services that are secured by TLS using DT LS.		This document specifies an ALPN ID for CoAP services that are secured by DTLS.
	An ALPN ID for CoAP services secured by TLS has already been specified in {{-coap-tcp }}.		An ALPN ID for CoAP services secured by TLS has already been specified in {{-coap-tcp }}.
	# Application-Layer Protocol Negotiation (ALPN) IDs		# Application-Layer Protocol Negotiation (ALPN) IDs
	For CoAP over TLS, an ALPN ID is defined as "coap" in {{-coap-tcp}}.		For CoAP over TLS, an ALPN ID is defined as "coap" in {{-coap-tcp}}.
	As it is not advisable to reuse the same ALPN ID for a different transport layer, an ALPN for		As it is not advisable to reuse the same ALPN ID for a different transport layer, an ALPN for
	CoAP over DTLS is registered in {{iana}}.		CoAP over DTLS is registered in {{iana}}.
	ALPN ID values have variable length.		ALPN ID values have variable length.
	For CoAP over DTLS, a short value ("co") is allocated, as this can avoid fragmentatio n of Client Hello and Server Hello messages in constrained networks with link-layer f ragmentation, such as 6LoWPAN {{-6lo}}.		For CoAP over DTLS, a short value ("co") is allocated, as this can avoid fragmentatio n of Client Hello and Server Hello messages in constrained networks with link-layer f ragmentation, such as 6LoWPAN {{-6lo}}.
	skipping to change at line 220 ¶		skipping to change at line 168 ¶
	--- back		--- back
	# Acknowledgments		# Acknowledgments
	{:unnumbered}		{:unnumbered}
	We would like to thank {{{Rich Salz}}} for the expert review on the "co" ALPN ID allo cation.		We would like to thank {{{Rich Salz}}} for the expert review on the "co" ALPN ID allo cation.
	We would also like to thank {{{Mohamed Boucadair}}} and {{{Ben Schwartz}}} for their early reviews before WG adoption		We would also like to thank {{{Mohamed Boucadair}}} and {{{Ben Schwartz}}} for their early reviews before WG adoption
	of this specification and {{{Esko Dijk}}}, {{{Thomas Fossati}}}, and {{{Marco Tiloca} }} for their feedback and comments.		of this specification and {{{Esko Dijk}}}, {{{Thomas Fossati}}}, and {{{Marco Tiloca} }} for their feedback and comments.
	<!--[rfced] Please review the "Inclusive Language" portion of the online Style		This work was supported in parts by the German Federal Ministry of Research, Technolo
	Guide <https://www.rfc-editor.org/styleguide/part2/#inclusive_language> and		gy, and Space (BMFTR) under the grant numbers 16KIS1386K (TU Dresden) and 16KIS1387 (
	let us know if any changes are needed. Updates of this nature typically		HAW Hamburg) within the research project PIVOT and under the grant numbers 16KIS1694K
	result in more precise language, which is helpful for readers.		(TU Dresden) and 16KIS1695 (HAW Hamburg) within the research project C-ray4edge.
	Note that our script did not flag any words in particular, but this should
	still be reviewed as a best practice.
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