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+Network Working Group W. Naylor
+Request for Comment: 619 H. Opderbeck
+NIC 21990 UCLA-NMC
+ March 7, 1974
+
+
+ Mean Round-Trip Times in the ARPANET
+
+
+In one of our current measurement projects we are interested in the
+average values of important network parameters. For this purpose we
+collect data on the network activity over seven consecutive days. This
+data collection is only interrupted by down-time or maintenance of
+either the net or our collecting facility (the "late" Sigma-7 or, in
+future, the 360/91 at CCN).
+
+The insight gained from the analysis of this data has been reported in
+Network Measurement Group Note 18 (NIC 20793):
+
+ L. Kleinrock and W. Naylor
+ "On Measured Behavior of the ARPA Network"
+
+This paper will be presented at the NCC '74 in Chicago.
+
+In this RFC we want to report the mean round-trip times (or delays) that
+were observed during these week-long measurements since we think these
+figures are of general interest to the ARPA community. Let us first
+define the term "round trip time" as it is used by the statistics
+gathering program in the IMPs. When a message is sent from a source
+HOST to a destination HOST, the following events, among others, can be
+distinguished (T(i) is the time of event i):
+
+ T(1): The message is passed from the user program to the NCP in the
+ source HOST
+
+ T(2): The proper entry is made in the pending packet table (PPT) for
+ single packet messages or the pending leader table (PLT) for
+ multiple packet messages after the first packet is received by
+ the source IMP
+
+ T(3): The first packet of the message is put on the proper output
+ queue in the source IMP (at this time the input of the second
+ packet is initiated)
+
+ T(4): The message is put on the HOST-output queue in the destination
+ IMP (at this time the reassembly of the message is complete)
+
+ T(5): The RFNM is sent from the destination IMP to the source IMP
+
+
+
+Naylor & Opderbeck [Page 1]
+
+RFC 619 Mean Round-Trip Times in the ARPANET March 1974
+
+
+ T(6): The RFNM arrives at the source IMP
+
+ T(7): The RFNM is accepted by the source HOST
+
+The time intervals T(i)-T(i-1) are mainly due to the following delays
+and waiting times:
+
+ T(2)-T(1): -HOST processing delay
+ -HOST-IMP transmission delay for the 32-bit leader
+ -Waiting time for a message number to become free (only
+ four messages can simultaneously be transmitted between
+ any pair of source IMP - destination IMP)
+ -Waiting time for a buffer to become free (there must be
+ more than three buffers on the "free buffer list")
+ -HOST-IMP transmission delay for the first packet
+ -Waiting time for an entry in the PPT or PLT to become
+ available (there are eight entries in the PPT and twelve
+ in the PLT table)
+
+ T(3)-T(2): -Waiting time for a store-and-forward (S/F) buffer to
+ become free (the maximum number of S/F-buffers is 20).
+ -Waiting time for a logical ACK-channel to become free
+ (there are 8 logical ACK-channels for each physical
+ channel).
+ -For multiple packet messages, waiting time until the
+ ALLOCATE is received (unless an allocation from a previous
+ multiple-packet message still exists; such an allocation
+ is returned in the RFNM and expires after 125 msec)
+
+ T(4)-T(3): -Queuing delay, transmission delay, and propagation delay
+ in all the IMPs and lines in the path from source IMP to
+ destination IMP
+ -Possibly retransmission delay due to transmission errors
+ or lack of buffer space (for multiple packet messages the
+ delays for the individual packets overlap)
+
+ T(5)-T(4): -Queuing delay in the destination IMP
+ -IMP-HOST transmission delay for the first packet
+ -For multiple-packet messages, waiting time for reassembly
+ buffers to become free to piggy-back an ALLOCATE on the
+ RFNM (if this waiting time exceeds one second then the
+ RFNM is sent without the ALLOCATE)
+
+ T(6)-T(5): -Queuing delay, transmission delay, and propagation delay
+ for the RFNM in all the IMPs and lines in the path from
+ destination IMP to source IMP
+
+
+
+
+
+Naylor & Opderbeck [Page 2]
+
+RFC 619 Mean Round-Trip Times in the ARPANET March 1974
+
+
+ T(7)-T(6): -Queuing delay for the RFNM in the source IMP
+ -IMP-HOST transmission delay for the RFNM
+
+IMP processing delays are not included in this table since they are
+usually very small. Also, some of the abovementioned waiting times
+reduce to zero in many cases, e.g. the waiting time for a message number
+to become available and the waiting time for a buffer to become free.
+
+If the source and destination HOSTs are attached to the same IMP, this
+table can be simplified as follows:
+
+ T(2)-T(1): as before
+ T(3)-T(2): for multiple packet messages: waiting time until
+ reassembly space becomes available (there are up to 66
+ reassembly buffers)
+ T(4)-T(3): for multiple packet messages: HOST-IMP transmission delay
+ for packets 2,3,...
+ T(5)-T(4): as before
+ T(6)-T(5): 0
+ T(7)-T(6): as before
+
+Up to now we have neglected the possibility that a single packet message
+is rejected at the destination IMP because of lack of reassembly space.
+If this occurs, the single packet message is treated as a request for
+buffer space allocation and the time interval T(3)-T(2) increased by the
+waiting time until the corresponding "ALLOCATE" is received.
+
+The round trip time (RTT) is now defined as the time interval T(6)-T(2).
+Note that the RTT for multiple packet messages does include the waiting
+time until the ALLOCATE is received. It does, however, not include the
+source HOST processing delay (i.e. delays in the NCP), the HOST-IMP
+transmission delay, and the waiting time until a message number becomes
+available. Note also, that the RFNM is sent after the first packet of a
+multiple packet message has been received by the destination HOST.
+
+Let us now turn to the presentation of the average round trip times as
+they were measured during continuous seven-day periods in August and
+December '73. In August, an average number of 2935 messages/minute were
+entering the ARPANET. The overall mean round trip delay for all these
+messages was 93 milliseconds (msec). The corresponding numbers for
+December were 2226 messages/minute and 200 msec. An obvious question
+that immediately arises is: why did the average round trip delay more
+than double while the rate of incoming messages decreased? The answer
+to this question can be found in the large round trip delays for the
+status reports that are sent from each IMP to the NCC. Each IMP sends,
+on the average, 2.29 status reports per minute to the NCC. Since there
+
+
+
+
+
+Naylor & Opderbeck [Page 3]
+
+RFC 619 Mean Round-Trip Times in the ARPANET March 1974
+
+
+were 45 sites connected to the net in December, a total of 103.05 status
+reports per minute were sent to the NCC. Thus 4.63 percent of all
+messages that entered the net were status reports.
+
+The average round trip delay for all these status reports in December
+was 1.66 sec. This number is five to ten times larger than the average
+round-trip delay for status reports we observed in August. It is not
+yet clear what change in the collection of status reports caused this
+increase. One reason appears to be that the number of these reports was
+doubled between August and December. Since the large round-trip delays
+of these status reports distort the overall picture somewhat, we are
+going to present the December data - wherever appropriate - with and
+without the effect of these delays. (We should point out here that the
+traffic/delay picture is distorted by the accumulated statistics
+messages which were collected to produce this data. We have, however,
+ignored this effect since these measurement messages represent less than
+0.3% of the total traffic.) The overall mean round trip delay without
+the status reports in December is 132 msec. This value is still more
+than 35 msec larger than the corresponding value for August. However,
+before we shall attempt to explain this difference we will first present
+the measured data.
+
+Table 1 shows the mean round trip delay as a function of the number of
+hops over the minimum-hop path. This minimum number of hops was
+calculated from the (static) topology of the net as it existed in August
+and December of last year. The actual number of hops over which any
+given message travels may, of course, be larger due to network
+congestion, line failures or IMP failures. In fact, for August we
+observed a minimum mean path length of 3.24 while the actual measured
+mean path length was 3.30; in December we observed 4.02 and 4.40,
+respectively. (See Network Measurement Group Note #18 for an
+explanation of the computation of actual mean path length.) As expected
+we observe a sharp increase of the mean round trip delay as the minimum
+number of hops is increased. Note, however, that the mean round trip
+delay is not a strictly increasing function of the minimum number of
+hops.
+
+Table 2 gives the mean round trip delay for messages from a given site.
+The December data is presented with and without the large delays
+incurred by the sending of status reports to the NCC. Table 3 shows the
+mean round trip delay for messages to a given site. The largest round
+trip delays, in December, were incurred by messages sent to the NCC-TIP
+since these messages include all the status reports.
+
+Table 4, finally, gives for each site the mean round trip delays to
+those three destination IMP/TIP's to which the most messages were sent
+during the seven-day measurement period in December. Let us first say
+few words about the traffic distribution which is dealt with in more
+
+
+
+Naylor & Opderbeck [Page 4]
+
+RFC 619 Mean Round-Trip Times in the ARPANET March 1974
+
+
+detail in Network Measurement Group Note #18. There are several sites
+which like to use their IMP as a kind of local multiplexer (UTAH, MIT,
+HARV, CMU, USCT, CCAT, XROX, HAWT, MIT2). For these sites the most
+favorite destination site is the source IMP itself. For several other
+sites the most favorite destination site is just one hop away (BBN,
+AMES, AMST, NCCT, RUTT). Nobody will be surprised that for many sites
+ISI (ILL, MTRT, ETAT, SDAT, ARPT, RMLT, LONT) or SRI (UCSB, RADT, NBST)
+is the most favorite site. There are several other sites (SDC, LL,
+CASE, DOCT, BELV, ABRD, FNWT, LBL, NSAT, TYMT, MOFF, WPAT) which were
+rather inactive in terms of generating traffic during the seven-day
+measurement period in December. Most of their messages were status
+reports sent to the NCC. (Those IMPs, for which the frequency of
+messages to the NCC-TIP is less than 2.2 messages per minute, were down
+for some time during the measurement period).
+
+Let us now attempt to give a few explanations for the overall increase
+in the mean round trip delay between August and December. These
+explanations may also help to understand the differences in the mean
+round trip delays for any given source IMP-destination IMP pair as
+observed in Table 4.
+
+1. Frequency of routing messages. Routing messages are the major
+ source of queuing delay in a very lightly loaded net. In August, a
+ routing message was sent every 640 msec. Since a routing message is
+ 1160 bits long, 3.625 percent of the bandwidth of a 50 kbs circuit
+ was used for the sending of routing messages. For randomly arriving
+ packets this corresponds to a mean queuing delay of 0.42 msec per
+ hop. Between August and December the frequency of sending routing
+ messages was made dependent on line speed and line utilization. As
+ a result, routing messages are now sent on a 50 kbs circuit with
+ zero load every 128 msec. This corresponds to a line utilization of
+ 18.125 percent and a mean queuing delay of 2.10 msec. The queuing
+ delay due to routing messages in a very lightly loaded net in
+ December was therefore five times as large as it was in August.
+
+2. Traffic matrix. The overall mean round trip delay depends on the
+ traffic matrix. If most of the messages are sent over distances of
+ 0 or 1 hop the overall round trip delay will be small. The heavy
+ traffic between AMES and AMST over a high-speed circuit in August
+ contributed to the small overall mean round trip delay.
+
+3. Network topology. The mean round trip delay depends on the number
+ of hops between source-IMP and destination-IMP and therefore on the
+ network topology. Disregarding line or IMP failures, the mean
+ number of hops for a message in August and December was,
+ respectively, 3.24 and 4.02.
+
+
+
+
+
+Naylor & Opderbeck [Page 5]
+
+RFC 619 Mean Round-Trip Times in the ARPANET March 1974
+
+
+4. Averaging. The network load, given in number or messages per
+ minute, represents an average over a seven-day period. Even though
+ this number may be small, considerable queuing delays could have
+ been incurred during bursts of traffic.
+
+5. Host delays. The round trip delay includes the transmission delay
+ of the first packet from the destination-IMP to the destination-
+ HOST; therefore, the mean round trip delay may be influenced by HOST
+ delays that are independent of the network load.
+
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+Naylor & Opderbeck [Page 6]
+
+RFC 619 Mean Round-Trip Times in the ARPANET March 1974
+
+
+ Table 1 Mean Round Trip Delay as a
+ Function of the Number of Hops
+
+ #MESSAGES/MINUTE #SITE PAIRS MEAN ROUND TRIP DELAY
+HOPS AUG DEC AUG DEC AUG DEC DEC
+ WITH W/OUT
+ STAT STAT
+ RPTS RPTS
+O 646.9 378.3 39 45 27 44 41
+
+1 487.6 288.7 86 100 25 65 50
+
+2 191.0 143.1 118 138 70 119 80
+
+3 380.7 226.9 148 168 95 131 112
+
+4 218.5 274.1 176 196 102 167 119
+
+5 276.3 185.6 204 228 109 217 134
+
+6 183.8 136.3 210 258 175 355 167
+
+7 333.6 212.7 218 256 178 301 240
+
+8 156.7 161.1 160 234 222 365 241
+
+9 59.0 160.3 102 208 270 308 218
+
+10 0.6 29.9 40 124 331 939 410
+
+11 1.0 18.9 20 46 344 998 699
+
+12 - 10.2 - 20 - 992 655
+
+13 - 0.01 - 4 - 809 809
+
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+Naylor & Opderbeck [Page 7]
+
+RFC 619 Mean Round-Trip Times in the ARPANET March 1974
+
+
+ Table 2 Mean Round Trip Delays for Messages from a Given Site
+
+ #MESSAGES/MINUTE MEAN ROUND TRIP DELAY
+ SITE AUGUST DECEMBER AUGUST DECEMBER DECEMBER
+ WITH WITHOUT
+ STATUS STATUS
+ REPORTS REPORTS
+ 1 UCLA 50.7 40.3 130 282 165
+ 2 SRI 377.3 147.9 45 189 174
+ 3 UCSB 80.2 70.3 120 221 161
+ 4 UTAH 27.0 46.2 136 247 169
+ 5 BBN 120.4 128.3 110 133 133
+ 6 MIT 120.6 96.9 126 160 150
+ 7 RAND 29.3 34.2 127 323 208
+ 8 SDC 1.7 2.4 521 2068 131
+ 9 HARV 50.3 96.0 105 88 72
+10 LL 4.4 6.7 201 602 187
+11 STAN 49.7 39.7 173 300 191
+12 ILL 26.8 53.4 158 216 165
+13 CASE 57.6 2.5 138 1592 335
+14 CMU 61.1 59.5 153 220 170
+15 AMES 242.4 114.1 43 120 81
+16 AMST 304.0 163.0 39 94 67
+17 MTRT 89.5 60.0 126 199 142
+18 RADT 27.7 29.1 145 273 160
+19 NBST 98.4 48.2 118 213 152
+20 ETAT 24.1 20.6 119 280 119
+21 LLL - 6.8 - 721 169
+22 ISI 372.0 304.4 110 147 142
+23 USCT 298.1 210.3 60 92 70
+24 GWCT 10.5 14.1 144 381 102
+25 DOCT 5.5 7.0 236 791 171
+26 SDAT 14.7 22.9 164 322 177
+27 BELV 1.3 2.4 243 1469 466
+28 ARPT 57.9 64.3 84 150 93
+29 ABRD 1.3 2.4 183 1402 554
+30 BBNT 40.8 10.0 75 372 124
+31 CCAT 177.7 86.7 83 147 115
+32 XROX 56.8 71.7 79 136 78
+33 FNWT 2.3 3.5 347 1466 174
+34 LBL 1.2 2.7 384 1653 621
+35 UCSD 11.9 19.3 237 413 205
+36 HAWT 27.5 5.2 654 569 476
+37 RMLT 10.4 13.0 122 387 97
+40 NCCT - 59.3 - 110 97
+41 NSAT 0.6 3.4 1022 1870 1056
+42 LONT - 20.8 - 998 848
+43 TYMT - 3.7 - 1352 157
+
+
+
+Naylor & Opderbeck [Page 8]
+
+RFC 619 Mean Round-Trip Times in the ARPANET March 1974
+
+
+44 MIT2 - 5.6 - 720 100
+45 MOFF - 2.4 - 1982 447
+46 RUTT - 22.4 - 271 153
+47 WPAT - 2.7 - 1399 380
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+Naylor & Opderbeck [Page 9]
+
+RFC 619 Mean Round-Trip Times in the ARPANET March 1974
+
+
+ Table 3 Mean Round Trip Delay for Messages to a Given Site
+ #MESSAGES/MINUTE MEAN ROUND TRIP DELAY
+ SITE AUGUST DECEMBER AUGUST DECEMBER
+ 1 UCLA 57.1 43.5 134 209
+ 2 SRI 382.3 149.4 45 158
+ 3 UCSB 61.1 59.1 117 138
+ 4 UTAH 28.1 50.4 128 159
+ 5 BBN 160.8 149.2 185 110
+ 6 MIT 150.4 107.1 116 130
+ 7 RAND 22.6 25.0 95 161
+ 8 SDC 1.7 0.8 149 174
+ 9 HARV 59.3 98.3 101 70
+10 LL 4.6 5.2 195 202
+11 STAN 65.3 40.6 135 162
+12 ILL 29.1 69.8 156 149
+13 CASE 52.6 4.0 127 262
+14 CMU 74.8 68.9 135 165
+15 AMES 210.3 117.2 40 75
+16 AMST 316.7 135.0 38 86
+17 MTRT 77.7 51.7 130 151
+18 RADT 23.4 23.9 142 202
+19 NBST 92.2 39.5 125 169
+20 ETAT 25.4 22.8 110 111
+21 LLL - 3.7 - 185
+22 ISI 361.9 299.2 107 130
+23 USCT 298.1 190.6 60 68
+24 GWCT 10.5 7.3 144 122
+25 DOCT 5.5 4.2 236 187
+26 SDAT 13.3 19.7 149 177
+27 BELV 0.9 0.9 196 285
+28 ARPT 55.4 58.3 78 95
+29 ABRD 1.3 0.7 183 271
+30 BBNT 40.8 6.4 75 159
+31 CCAT 177.7 76.3 83 119
+32 XROX 56.8 75.3 79 69
+33 FNWT 2.3 1.4 347 165
+34 LBL 1.2 0.9 384 305
+35 UCSD 11.9 24.0 237 157
+36 HAWT 27.5 5.0 654 458
+37 RMLT 10.4 11.0 122 97
+40 NCCT - 140.1 - 1263
+41 NSAT 0.6 1.6 1022 918
+42 LONT - 17.3 - 855
+43 TYMT - 1.6 - 160
+44 MIT2 - 3.9 - 83
+45 MOFF - 0.2 - 219
+46 RUTT - 14.7 - 153
+47 WPAT - 0.5 - 282
+
+
+
+Naylor & Opderbeck [Page 10]
+
+RFC 619 Mean Round-Trip Times in the ARPANET March 1974
+
+
+ Table 4 Mean Round Trip Delay to the Three Most Favorite Sites
+
+ #MESSAGES/MINUTE MEAN ROUND TRIP DELAY
+FROM SITE TO SITE AUGUST DECEMBER AUGUST DECEMBER
+
+ 1 UCLA 1 RAND 10.8 9.4 57 92
+ 26 SDAT 5.6 5.9 157 191
+ 22 ISI 3.1 3.1 99 146
+
+ 2 SRI 12 RADT 16.6 19.5 142 163
+ 17 MTRT 21.9 18.7 140 161
+ 2 SRI 266.1 17.5 14 69
+
+ 3 UCSB 2 SRI 8.1 17.8 72 68
+ 22 ISI 18.1 17.0 75 86
+ 14 CMU 16.6 11.8 140 152
+
+ 4 UTAH 4 UTAH 3.5 13.5 136 27
+ 22 ISI 3.7 4.8 131 165
+ 5 BBN 4.2 4.1 168 204
+
+ 5 BBN 40 NCCT - 81.4 - 105
+ 5 BBN 12.5 19.7 102 37
+ 9 HARV 0.5 9.2 22 37
+
+ 6 MIT 6 MIT 40.6 24.0 81 85
+ 23 USCT 9.8 13.9 150 173
+ 9 HARV 1.7 12.0 63 88
+
+ 7 RAND 1 UCLA 12.5 10.4 54 96
+ 16 AMST 0.8 2.6 99 190
+ 40 NCCT - 2.5 - 1941
+
+ 8 SDC 40 NCCT - 2.2 - 2217
+ 1 UCLA 0.2 0.2 110 136
+ 8 SDC 0.01 0.01 93 13
+
+ 9 HARV 9 HARV 7.6 50.5 49 21
+ 2 MIT 1.6 11.9 62 85
+ 5 BBN 1.6 9.5 56 37
+
+10 LL 40 NCCT - 2.2 - 1420
+ 10 LL 1.5 1.8 238 135
+ 24 GWCT 0.04 0.6 146 80
+
+11 STAN 14 CMU 3.0 7.0 215 207
+ 4 UTAH 0.2 5.5 117 117
+ 6 MIT 6.5 5.0 186 225
+
+
+
+Naylor & Opderbeck [Page 11]
+
+RFC 619 Mean Round-Trip Times in the ARPANET March 1974
+
+
+12 ILL 22 ISI 13.3 20.3 146 142
+ 15 AMES 0.8 14.6 109 135
+ 35 UCSD 6.7 6.5 192 269
+
+13 CASE 40 NCCT - 2.2 - 1744
+ 1 UCLA 0.2 0.2 296 400
+ 2 SRI 7.1 0.01 163 316
+
+14 CMU 14 CMU 13.8 23.4 129 94
+ 3 UCSB 13.8 9.2 153 166
+ 11 STAN 3.2 5.1 193 209
+
+15 AMES 16 AMST 205.0 65.8 15 34
+ 12 ILL 1.2 19.6 115 120
+ 31 CCAT 3.2 4.6 174 230
+
+16 AMST 15 AMES 176.8 74.3 13 28
+ 22 ISI 63.6 33.2 50 69
+ 32 XROX 13.3 17.4 41 60
+
+17 MTRT 22 ISI 26.3 27.5 115 118
+ 2 SRI 23.8 20.3 137 155
+ 5 BBN 3.5 4.2 179 133
+
+18 RADT 2 SRI 17.7 21.7 139 156
+ 1 UCLA 0.4 2.3 265 181
+ 40 NCCT - 2.3 - 1618
+
+19 NBST 2 SRI 14.1 12.1 132 163
+ 22 ISI 29.6 11.8 100 117
+ 5 BBN 21.6 9.6 71 97
+
+20 ETAT 22 ISI 11.9 11.3 106 107
+ 24 GWCT 5.0 5.9 99 107
+ 40 NCCT - 2.2 - 1602
+
+21 LLL 5 BBN - 2.9 - 183
+ 40 NCCT - 2.2 - 1847
+ 4 UTAH - 0.5 - 71
+
+22 ISI 28 ARPT 26.0 38.3 106 104
+ 23 USCT 69.0 32.7 80 92
+ 16 AMST 62.0 28.5 53 87
+
+23 USCT 23 USCT 160.9 119.2 19 23
+ 22 ISI 69.2 34.1 78 91
+ 6 MIT 12.9 19.6 135 150
+
+
+
+
+Naylor & Opderbeck [Page 12]
+
+RFC 619 Mean Round-Trip Times in the ARPANET March 1974
+
+
+24 GWCT 20 ETAT 6.6 10.8 93 91
+ 40 NCCT - 2.1 - 1978
+ 10 LL 0.03 0.5 359 115
+
+25 DOCT 40 NCCT - 2.3 - 2091
+ 22 ISI 1.0 1.6 220 118
+ 15 AMES 1.9 1.2 167 198
+
+26 SDAT 22 ISI 2.9 8.7 154 138
+ 1 UCLA 5.9 6.0 169 209
+ 2 SRI 1.0 4.4 182 184
+
+27 BELV 40 NCCT - 2.2 - 1553
+ 1 UCLA 0.1 0.2 405 517
+ 22 ISI - 0.01 - 325
+
+28 ARPT 22 ISI 27.4 41.6 106 101
+ 28 ARPT 19.2 13.7 20 35
+ 2 SRI 3.3 3.3 139 157
+
+29 ABRD 40 NCCT - 2.2 - 1461
+ 1 UCLA 0.2 0.2 439 562
+ 9 HARV - 0.01 - 112
+
+30 BBNT 5 BBN 24.2 5.1 36 64
+ 40 NCCT - 2.1 - 1327
+ 22 ISI 4.2 1.1 170 217
+
+31 CCAT 31 CCAT 81.9 28.2 15 31
+ 22 ISI 31.3 23.3 156 171
+ 5 BBN 7.8 7.3 45 42
+
+32 XROX 32 XROX 20.2 36.4 19 15
+ 16 AMST 10.5 13.3 69 93
+ 14 CMU 2.5 3.0 193 251
+
+33 FNWT 40 NCCT - 2.2 - 2210
+ 9 HARV 0.01 0.3 208 194
+ 7 RAND 0.3 0.3 96 171
+
+34 LBL 40 NCCT - 2.4 - 1814
+ 41 NSAT - 0.2 - 1674
+ 1 UCLA 0.1 0.2 295 478
+
+35 UCSD 12 ILL 6.0 7.5 220 260
+ 16 AMST 1.7 4.9 120 172
+ 40 NCCT - 2.0 - 2183
+
+
+
+
+Naylor & Opderbeck [Page 13]
+
+RFC 619 Mean Round-Trip Times in the ARPANET March 1974
+
+
+36 HAWT 36 HAWT 0.04 1.6 17 26
+ 22 ISI 5.1 1.0 600 623
+ 15 AMES 2.5 0.8 551 590
+
+37 RMLT 22 ISI 7.5 9.0 68 67
+ 40 NCCT - 2.2 - 1918
+ 28 ARPT - 1.0 - 63
+
+40 NCCT 5 BBN - 41.2 - 33
+ 40 NCCT - 6.6 - 433
+ 22 ISI - 3.2 - 151
+
+41 NSAT 40 NCCT - 2.2 - 2308
+ 2 SRI 0.01 0.4 1046 1002
+ 3 UCSB 0.01 0.2 1169 1018
+
+42 LONT 22 ISI - 6.1 - 837
+ 2 SRI - 3.7 - 884
+ 4 UTAH - 2.2 - 921
+
+43 TYMT 40 NCCT - 2.6 - 1859
+ 2 SRI - 0.5 - 79
+ 3 UCSB - 0.2 - 74
+
+44 MIT2 44 MIT2 - 2.8 - 18
+ 40 NCCT - 2.3 - 1664
+ 1 UCLA - 0.2 - 589
+
+46 MOFF 40 NCCT - 2.2 - 2091
+ 1 UCLA - 0.2 - 447
+
+46 RUTT 9 HARV - 4.3 - 38
+ 5 BBN - 3.5 - 93
+ 22 ISI - 2.9 - 172
+
+47 WPAT 40 NCCT - 2.2 - 1643
+ 3 UCSB - 0.2 - 301
+ 1 UCLA - 0.2 - 671
+
+
+
+
+ [ This RFC was put into machine readable form for entry ]
+ [ into the online RFC archives by Alex McKenzie with ]
+ [ support from GTE, formerly BBN Corp. 12/99 ]
+
+
+
+
+
+
+Naylor & Opderbeck [Page 14]
+