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 |
      |
  84%_|            _____
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      |           |/////|_____
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      |_____ _____|/////|/////|_____ _____ _____ _____ _____ _____
    0_|________________________________________________________________ time
      |     |     |     |     |     |     |     |     |     |     |      ms
     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 |
      |
 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 |
      |
  44%_|                          _
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      |_ _ _ _ _ _ _ _ _ _ _|/|/|/|/|/|_ _ _ _ _ _ _ _ _ _ _ _ _ _
    0_|________________________________________________________________ time
      |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |      ms
     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 |
      |
  99%_|    _
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    0_|________________________________________________________________ time
      |     |     |     |     |     |     |     |     |     |     |      ms
      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 |
      |
  14%_|            _
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      |/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|/|_
    0_|________________________________________________________________ time
      |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |      ms
     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
      |     |     |     |     |     |     |     |     |     |     |      ms
      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 |
      |
  15%_|                  _
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    0_|________________________________________________________________ time
      |     |     |     |     |     |     |     |     |     |     |      ms
    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
      |     |     |     |     |     |     |     |     |     |     |      ms
      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 |
      |
  13%_|                _     _
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    0_|________________________________________________________________ time
      |     |     |     |     |     |     |     |     |     |     |      ms
    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 |
      |
  25%_|                                          _ _
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    0_|________________________________________________________________ time
      |     |     |     |     |     |     |     |     |     |     |      ms
      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 |
      |
  13%_|                _
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    0_|________________________________________________________________ time
      |     |     |     |     |     |     |     |     |     |     |      ms
    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 |
      |
  25%_|                                          _
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    0_|________________________________________________________________ time
      |     |     |     |     |     |     |     |     |     |     |      ms
      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 |
      |
  14%_|                      _
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    0_|________________________________________________________________ time
      |     |     |     |     |     |     |     |     |     |     |      ms
    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
      |     |     |     |     |     |     |     |     |     |     |      ms
      0    300   600   900  1200  1500  1800  2100  2400  2700  3000

                                - 8 -