Echo Delay Measurements With GGP Packets
IEN 163
R.G.Jones
November 1980
University College London
GGP IEN
Echo 163
Delays
1. Introduction
This IEN is intended to facilitate discussion of
internet delays as seen from the UK. It presents a
series of measurements of round trip times for GGP echo
packets.
The GGP packet generator was an LSI-11 host on the
UCL Port Expander (the UCLnet/SATNET/Nullnet gateway is
another host on this Port Expander). Round-trip times
were measured by timestamping the packet on initiation
of output and again on completion of input. The time
reference was a programmable clock with 1 millisecond
resolution (based on a 10 MHz crystal).
Echo delays were measured for the following
destinations:
address
UCLnet/SATNET/Nullnet gateway 11 3 0 42
RSRE PPSN/Nullnet gateway 35 6 0 0
Goonhilly SIMP 4 0 0 63
BBN SATNET/ARPANET gateway 4 0 0 61
Bragg PR/ARPANET gateway 10 0 0 38
SRI PR1/ARPANET gateway 10 3 0 51
SRI PR2/ARPANET gateway 10 1 0 51
For each destination, 1000 packets were sent at 4
second intervals.
The results are presented in the following pages.
Each page is devoted to one destination. Two histograms
are provided for the given destination, the upper
showing the structure of the distribution of times and
the lower with a scale common to all destinations to
simplify comparisons.
On each histogram the count is given as a percentage
of the total number of replies received. The heading
gives the total number of replies received for the 1000
packets sent; the minimum, maximum and average times
for all the replies; and the number of replies falling
within, above and below the histogram range plotted.
The round trip times given are in milliseconds. The
date of the experiment is in the English (day/month)
format and the time is given as GMT.
- 1 - R.G.Jones
ECHO DESTINATION UCL UCL/SAT gway DATE 17/11/80 TIME 14.00-15.07
1000 packets minimum time 30 maximum 40 average 32
999 within histogram range 0 below 1 above
count |
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84%_| _____
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0_|________________________________________________________________ time
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30 31 32 33 34 35 36 37 38 39 40
ECHO DESTINATION UCL UCL/SAT gway DATE 17/11/80 TIME 14.00-15.07
1000 packets minimum time 30 maximum 40 average 32
1000 within histogram range 0 below 0 above
count |
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100%_|_
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0_|________________________________________________________________ time
| | | | | | | | | | | ms
0 300 600 900 1200 1500 1800 2100 2400 2700 3000
- 2 -
ECHO DESTINATION RSRE PPSN/N gway DATE 14/11/80 TIME 12.15-13.22
1000 packets minimum time 244 maximum 346 average 263
983 within histogram range 5 below 12 above
count |
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44%_| _
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0_|________________________________________________________________ time
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250 252 254 256 258 260 262 264 266 268 270 272 274 276 278 280
ECHO DESTINATION RSRE PPSN/N gway DATE 14/11/80 TIME 12.15-13.22
1000 packets minimum time 244 maximum 346 average 263
1000 within histogram range 0 below 0 above
count |
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99%_| _
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0_|________________________________________________________________ time
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0 300 600 900 1200 1500 1800 2100 2400 2700 3000
- 3 -
ECHO DESTINATION Goonhilly SIMP DATE 17/11/80 TIME 10.05-11.12
997 packets minimum time 80 maximum 284 average 104
954 within histogram range 0 below 43 above
count |
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14%_| _
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|_|/|/|/|/|/|/|/|/|/|/|/|/|/|_|/|/|/|/|/|/|/|/|_ _ _ _ _ _
|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|_
0_|________________________________________________________________ time
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80 84 88 92 96 100 104 108 112 116 120 124 128 132 136 140
ECHO DESTINATION Goonhilly SIMP DATE 17/11/80 TIME 10.05-11.12
997 packets minimum time 80 maximum 284 average 104
997 within histogram range 0 below 0 above
count |
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61%_|_
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0_|________________________________________________________________ time
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0 300 600 900 1200 1500 1800 2100 2400 2700 3000
- 4 -
ECHO DESTINATION BBN SATNET/A gway DATE 17/11/80 TIME 8.40-9.47
994 packets minimum time 1443 maximum 4344 average 1929
983 within histogram range 0 below 11 above
count |
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15%_| _
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|_ _|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|_ _|/|/|_|/|_ _|/|_ _ _ _
0_|________________________________________________________________ time
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1400 1550 1700 1850 2000 2150 2300 2450 2600 2750 2900
ECHO DESTINATION BBN SATNET/A gway DATE 17/11/80 TIME 8.40-9.47
994 packets minimum time 1443 maximum 4344 average 1929
985 within histogram range 0 below 9 above
count |
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28%_| _
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0_|________________________________________________________________ time
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0 300 600 900 1200 1500 1800 2100 2400 2700 3000
- 5 -
ECHO DESTINATION Bragg PR/A gway DATE 12/11/80 TIME 9.45-10.52
1000 packets minimum time 1689 maximum 8402 average 2270
982 within histogram range 1 below 17 above
count |
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0_|________________________________________________________________ time
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1700 1850 2000 2150 2300 2450 2600 2750 2900 3050 3200
ECHO DESTINATION Bragg PR/A gway DATE 12/11/80 TIME 9.45-10.52
1000 packets minimum time 1689 maximum 8402 average 2270
975 within histogram range 0 below 25 above
count |
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0_|________________________________________________________________ time
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0 300 600 900 1200 1500 1800 2100 2400 2700 3000
- 6 -
ECHO DESTINATION SRI PR1/A gway DATE 14/11/80 TIME 11.00-12.07
998 packets minimum time 1715 maximum 5574 average 2266
978 within histogram range 0 below 20 above
count |
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0_|________________________________________________________________ time
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1700 1850 2000 2150 2300 2450 2600 2750 2900 3050 3200
ECHO DESTINATION SRI PR1/A gway DATE 14/11/80 TIME 11.00-12.07
998 packets minimum time 1715 maximum 5574 average 2266
970 within histogram range 0 below 28 above
count |
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0_|________________________________________________________________ time
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0 300 600 900 1200 1500 1800 2100 2400 2700 3000
- 7 -
ECHO DESTINATION SRI PR2/A gway DATE 14/11/80 TIME 9.50-10.57
999 packets minimum time 1764 maximum 5438 average 2265
976 within histogram range 0 below 23 above
count |
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14%_| _
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0_|________________________________________________________________ time
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1700 1850 2000 2150 2300 2450 2600 2750 2900 3050 3200
ECHO DESTINATION SRI PR2/A gway DATE 14/11/80 TIME 9.50-10.57
999 packets minimum time 1764 maximum 5438 average 2265
964 within histogram range 0 below 35 above
count |
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26%_| _
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0_|________________________________________________________________ time
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0 300 600 900 1200 1500 1800 2100 2400 2700 3000
- 8 -