Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.3 alpha 4/15/85; site ucbvax.ARPA Path: utzoo!watmath!clyde!bonnie!akgua!whuxlm!whuxl!houxm!ihnp4!ucbvax!tcp-ip From: tcp-ip@ucbvax.ARPA Newsgroups: fa.tcp-ip Subject: ARPANET/MILNET performance statistics Message-ID: <7688@ucbvax.ARPA> Date: Sat, 1-Jun-85 12:46:38 EDT Article-I.D.: ucbvax.7688 Posted: Sat Jun 1 12:46:38 1985 Date-Received: Sun, 2-Jun-85 04:30:57 EDT Sender: daemon@ucbvax.ARPA Organization: University of California at Berkeley Lines: 125 From: mills@dcn6.arpa Folks, Responding to Vint's request, here are some relevant data covering the ARPANET/MILNET gateway performance. The data have been extracted from the lastest weekly report produced by BBN and cover only the ARPANET/MILNET gateways, which represent only seven out of the 38 operational BBN core gateways. (Who knows how many non-core gateways there are out there...) The period covered by these data cover just short of a six-day period and detail the average and peak throughputs and loss rates. The totals shown are for all of the 38 gateways. Comments follow the tables. Total Throughput GWY RCVD RCVD IP % IP DEST % DST NAME DGRAMS BYTES ERRORS ERRORS UNRCH UNRCH ---------------------------------------------------------------------- MILARP 4,169,046 306,185,112 273 0.00% 7,153 0.17% MILBBN 4,638,747 272,396,860 458 0.00% 30,045 0.65% MILDCE 3,952,555 280,374,422 372 0.00% 23,747 0.60% MILISI 5,282,635 624,869,302 779 0.01% 20,353 0.39% MILLBL 2,896,764 175,123,126 143 0.00% 6,639 0.23% MILSAC 2,765,136 157,981,916 1,122 0.04% 10,588 0.38% MILSRI 2,133,985 117,968,018 169 0.00% 13,832 0.65% ---------------------------------------------------------------------- TOTALS 92,368,009 5,768,504,913 1,556,736 1.69% 190,545 0.21% GWY SENT SENT DROPPED % DROPPED NAME DGRAMS BYTES DGRAMS DGRAMS ------------------------------------------------------- MILARP 4,146,989 295,751,188 101,471 2.39% MILBBN 4,669,813 276,807,235 157,068 3.25% MILDCE 3,942,271 284,077,034 59,404 1.48% MILISI 5,138,585 577,311,096 247,222 4.59% MILLBL 2,877,744 174,574,553 55,537 1.89% MILSAC 2,792,073 165,159,590 13,393 0.48% MILSRI 2,156,255 127,256,463 53,483 2.42% ------------------------------------------------------- TOTALS 92,523,789 5,721,526,805 1,466,274 1.56% Note that the load balancing, while not optimal, is not too bad. The data do now show, of course, the extent of the double-hop inefficiencies pointed out previously. The ARPANET/MILNET gateways see fewer IP errors than average, but somewhat more broken networks and dropped packets than average. ====================================================== Mean Throughput (per second) and Size (bytes per datagram) GWY RCVD RCVD IP AVG BYTES NAME DGRAMS BYTES ERRORS PER DGRAM -------------------------------------------------------- MILARP 8.14 597.90 0.00 73.44 MILBBN 9.06 531.92 0.00 58.72 MILDCE 7.72 547.50 0.00 70.93 MILISI 10.32 1220.21 0.00 118.29 MILLBL 5.66 341.97 0.00 60.45 MILSAC 5.40 308.50 0.00 57.13 MILSRI 4.17 230.36 0.00 55.28 GWY SENT SENT DROPPED AVG BYTES NAME DGRAMS BYTES DGRAMS PER DGRAM ------------------------------------------------------- MILARP 8.10 577.53 0.20 71.32 MILBBN 9.12 540.53 0.31 59.28 MILDCE 7.70 554.73 0.12 72.06 MILISI 10.03 1127.34 0.48 112.35 MILLBL 5.62 340.90 0.11 60.66 MILSAC 5.45 322.51 0.03 59.15 MILSRI 4.21 248.50 0.10 59.02 These values are way below the maximum throughput of the LSI-11 gateways (about 200 packets/sec); however, the average size is very small relative to the maximum ARPANET/MILNET packet size of 1007 octets. One would expect the resource crunch to be the limited buffer memory available in the present LSI-11 implementation. Note that BBN is working actively toward a dramatic increase in available memory, as noted previously. ====================================================== Peak Throughput (sum of datagrams/sec, input + output, time is time of data collection) GWY TOTAL TIME DROP TIME NAME T'PUT OF DAY RATE OF DAY ------------------------------------------------------------------------ MILARP 47.28 5/24 09:16 27.26% 5/25 22:04 MILBBN 39.53 5/23 15:32 20.70% 5/24 02:18 MILDCE 36.67 5/24 08:02 26.12% 5/24 17:59 MILISI 44.45 5/23 15:02 32.39% 5/21 16:08 MILLBL 37.76 5/22 19:43 34.91% 5/24 12:02 MILSAC 36.91 5/23 13:03 5.75% 5/21 08:53 MILSRI 22.78 5/24 08:47 24.89% 5/21 16:08 Even under peak loads the gateway horsepower is not particularily taxed; however, the buffering is obviously suffering a good deal. The times of peak throughputs do not seem to correlate with the times of peak drop rates, which tends to confirm that most of the drops occur in bunches under conditions approaching congestive collapse. The instrumentation in our gateway beteen the ARPANET and four local nets, some of which are connected by medium-speed (4800/9600 bps) lines, tends to support the above observations and conclusions. We see intense spasms on the part of some hosts (names provided upon request) which clearly are to blame for almost all of the congestion observed here. These hosts apparently have been optimized to operate well on local Ethernets with small delays and tend to bombard the long-haul paths with vast numbers of retransmissions over very short intervals. I would bet a wadge of packets against a MicroVAX-II that the prime cause for the braindamage is ARP and the unfortunately common implementation that loses the first data packet during the address-resolution cycle. If this is fixed, I bet the tendency to err on the low side of retransmission estimates would go away. There are other causes of packet spasms that have been detailed in many of my previous messages. Happily, some have gone away. Those remaining symptoms indicate continuing inefficiencies in piggybacking and send/ack policies leading to tinygram floods (with TELNET, in particular). The sad fact is that these problems have been carefully documented and are not hard to fix; however, it takes only a few bandits without these fixes to torpedo the entire Internet performance. Dave -------