Slow TCP connections between 2.2.3 and HP-UX B.10.20 A 9000/800

bwoodard@cisco.com
Thu, 25 Mar 1999 09:50:59 -0800


I believe that I am seeing some sort of bad interaction between Linux
2.2.3 and HP-UX B.10.20 A. The symptoms are that the _ALL_ TCP
connections from this one HP-UX box to the Linux 2.2.3 machine proceed
very slowly. i.e. 16-50Kb/s We first observed the problem with LPD but
it is easily reproducable using FTP.

Both machines are lightly loaded and on very fast relativively
unloaded switched networks and are only seperated by one router. (The
network is good; this is Cisco ;->)

traceroute to soot.cisco.com (171.68.225.45), 30 hops max, 40 byte packets
1 server-gw10 (171.68.10.131) 0.377 ms 0.953 ms 0.575 ms
2 soot (171.68.225.45) 0.703 ms 0.502 ms 0.577 ms

The problem doesn't to occur with a machine on the same subnet which
is running 2.0.36 kernel. I've got a suspicion that the slow start
algorithm is some how at fault but I don't know enough to really tell
for sure. Could someone look at this tcpdump and tell me if we have
tickled a bug in 2.2's TCP code? (Soot is the hp-ux and neithan is the
linux machine)

08:24:50.282526 soot.cisco.com.2363 > neithan.ftp: P 42112045:42112070(25) ack 992727448 win 32768 (DF)
08:24:50.282697 neithan.ftp > soot.cisco.com.2363: P 1:31(30) ack 25 win 32120 (DF) [tos 0x10]
08:24:50.284818 soot.cisco.com.2363 > neithan.ftp: P 25:35(10) ack 31 win 32768 (DF)
08:24:50.285720 neithan.ftp-data > soot.cisco.com.2374: S 1122078660:1122078660(0) win 32120 <mss 1460,sackOK,timestamp 15130668[|tcp]> (DF) [tos 0x8]
08:24:50.286290 soot.cisco.com.2374 > neithan.ftp-data: S 60224000:60224000(0) ack 1122078661 win 57344 <mss 1460> (DF)
08:24:50.286319 neithan.ftp-data > soot.cisco.com.2374: . ack 1 win 32120 (DF) [tos 0x8]
08:24:50.286395 neithan.ftp > soot.cisco.com.2363: P 31:81(50) ack 35 win 32120 (DF) [tos 0x10]
08:24:50.309760 soot.cisco.com.2363 > neithan.ftp: . ack 81 win 32768 (DF)
08:24:50.315653 soot.cisco.com.2374 > neithan.ftp-data: . 1:1461(1460) ack 1 win 57344 (DF)
08:24:50.315691 neithan.ftp-data > soot.cisco.com.2374: . ack 1461 win 30660 (DF) [tos 0x8]
08:24:50.315809 soot.cisco.com.2374 > neithan.ftp-data: . 1461:2921(1460) ack 1 win 57344 (DF)
08:24:50.317447 soot.cisco.com.2374 > neithan.ftp-data: . 2921:4381(1460) ack 1 win 57344 (DF)
08:24:50.317483 neithan.ftp-data > soot.cisco.com.2374: . ack 4381 win 30660 (DF) [tos 0x8]
08:24:50.317611 soot.cisco.com.2374 > neithan.ftp-data: . 4381:5841(1460) ack 1 win 57344 (DF)
08:24:50.319387 neithan.ftp-data > soot.cisco.com.2374: . ack 5841 win 32120 (DF) [tos 0x8]
08:24:50.319699 soot.cisco.com.2374 > neithan.ftp-data: . 7301:8761(1460) ack 1 win 57344 (DF)
08:24:50.319738 neithan.ftp-data > soot.cisco.com.2374: . ack 5841 win 32120 (DF) [tos 0x8]
08:24:50.319822 soot.cisco.com.2374 > neithan.ftp-data: . 8761:10221(1460) ack 1 win 57344 (DF)
08:24:50.319859 neithan.ftp-data > soot.cisco.com.2374: . ack 5841 win 32120 (DF) [tos 0x8]
08:24:50.321378 soot.cisco.com.2374 > neithan.ftp-data: . 10221:11681(1460) ack 1 win 57344 (DF)
08:24:50.321414 neithan.ftp-data > soot.cisco.com.2374: . ack 5841 win 32120 (DF) [tos 0x8]
08:24:50.321543 soot.cisco.com.2374 > neithan.ftp-data: . 11681:13141(1460) ack 1 win 57344 (DF)
08:24:50.321578 neithan.ftp-data > soot.cisco.com.2374: . ack 5841 win 32120 (DF) [tos 0x8]
08:24:50.323016 soot.cisco.com.2374 > neithan.ftp-data: . 5841:7301(1460) ack 1 win 57344 (DF)
08:24:50.323053 neithan.ftp-data > soot.cisco.com.2374: . ack 13141 win 27740 (DF) [tos 0x8]
08:24:50.325475 soot.cisco.com.2374 > neithan.ftp-data: . 13141:14601(1460) ack 1 win 57344 (DF)
08:24:50.325640 soot.cisco.com.2374 > neithan.ftp-data: . 14601:16061(1460) ack 1 win 57344 (DF)
08:24:50.325678 neithan.ftp-data > soot.cisco.com.2374: . ack 16061 win 30660 (DF) [tos 0x8]
08:24:50.325762 soot.cisco.com.2374 > neithan.ftp-data: . 16061:17521(1460) ack 1 win 57344 (DF)
08:24:50.328424 soot.cisco.com.2374 > neithan.ftp-data: . 20441:21901(1460) ack 1 win 57344 (DF)
08:24:50.328464 neithan.ftp-data > soot.cisco.com.2374: . ack 17521 win 30660 (DF) [tos 0x8]
08:24:50.328588 soot.cisco.com.2374 > neithan.ftp-data: . 21901:23361(1460) ack 1 win 57344 (DF)
08:24:50.328625 neithan.ftp-data > soot.cisco.com.2374: . ack 17521 win 30660 (DF) [tos 0x8]
08:24:50.330061 soot.cisco.com.2374 > neithan.ftp-data: . 23361:24821(1460) ack 1 win 57344 (DF)
08:24:50.330098 neithan.ftp-data > soot.cisco.com.2374: . ack 17521 win 30660 (DF) [tos 0x8]
08:24:51.280869 soot.cisco.com.2374 > neithan.ftp-data: . 17521:18981(1460) ack 1 win 57344 (DF)
08:24:51.280908 neithan.ftp-data > soot.cisco.com.2374: . ack 18981 win 29200 (DF) [tos 0x8]
08:24:51.282467 soot.cisco.com.2374 > neithan.ftp-data: . 18981:20441(1460) ack 1 win 57344 (DF)
08:24:51.282505 neithan.ftp-data > soot.cisco.com.2374: . ack 24821 win 29200 (DF) [tos 0x8]
08:24:51.282638 soot.cisco.com.2374 > neithan.ftp-data: . 20441:21901(1460) ack 1 win 57344 (DF)
08:24:51.282672 neithan.ftp-data > soot.cisco.com.2374: . ack 24821 win 30660 (DF) [tos 0x8]
08:24:51.284638 soot.cisco.com.2374 > neithan.ftp-data: . 24821:26281(1460) ack 1 win 57344 (DF)
08:24:51.284802 soot.cisco.com.2374 > neithan.ftp-data: . 26281:27741(1460) ack 1 win 57344 (DF)
08:24:51.284839 neithan.ftp-data > soot.cisco.com.2374: . ack 27741 win 30660 (DF) [tos 0x8]
08:24:51.284965 soot.cisco.com.2374 > neithan.ftp-data: . 27741:29201(1460) ack 1 win 57344 (DF)
08:24:51.286566 soot.cisco.com.2374 > neithan.ftp-data: . 29201:30661(1460) ack 1 win 57344 (DF)
08:24:51.286606 neithan.ftp-data > soot.cisco.com.2374: . ack 30661 win 30660 (DF) [tos 0x8]
08:24:51.286685 soot.cisco.com.2374 > neithan.ftp-data: . 30661:32121(1460) ack 1 win 57344 (DF)
08:24:51.288246 soot.cisco.com.2374 > neithan.ftp-data: . 32121:33581(1460) ack 1 win 57344 (DF)
08:24:51.288284 neithan.ftp-data > soot.cisco.com.2374: . ack 33581 win 30660 (DF) [tos 0x8]
08:24:51.288411 soot.cisco.com.2374 > neithan.ftp-data: . 33581:35041(1460) ack 1 win 57344 (DF)
08:24:51.290174 soot.cisco.com.2374 > neithan.ftp-data: . 35041:36501(1460) ack 1 win 57344 (DF)
08:24:51.290210 neithan.ftp-data > soot.cisco.com.2374: . ack 36501 win 30660 (DF) [tos 0x8]
08:24:51.290331 soot.cisco.com.2374 > neithan.ftp-data: . 36501:37961(1460) ack 1 win 57344 (DF)
08:24:51.291971 soot.cisco.com.2374 > neithan.ftp-data: . 39421:40881(1460) ack 1 win 57344 (DF)

...much deleted if you need more of the log please email me.

-ben

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