Date: Fri, 01 Feb 2002 10:36:20 +1100 From: Peter Jeremy <peter.jeremy@alcatel.com.au> To: freebsd-stable@freebsd.org Subject: TCP problems in 4.5-STABLE Message-ID: <20020201103619.A54287@gsmx07.alcatel.com.au>
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I've recently run into a problem that looks suspiciously similar to
the one that Matt fixed at the beginning of December last year.
The symptoms are that when transferring (using scp) a large file, the
throughput drops to 10-20kBps. The transfer starts out at full speed
and will slow down after a random time and doesn't seem to recover. I
originally noticed the problem with -STABLE from around Xmas, but
having just upgraded to -STABLE as of a couple of hours ago, the
problem still exists.
host1 is my desktop - a PII-266 running -CURRENT from early Jan'02
with an SMC EtherPower II NIC (tx):
tx0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet 192.168.123.247 netmask 0xffffff00 broadcast 192.168.123.255
ether 00:e0:29:24:34:1f
media: Ethernet autoselect (10baseT/UTP)
status: active
host2 is a Compaq Armada 1592DT (P-233) running -STABLE with a
3Com Etherlink III 3C589 (ep):
ep0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet 192.168.123.159 netmask 0xffffff00 broadcast 192.168.123.255
ether 00:50:04:b7:98:24
media: Ethernet 10baseT/UTP
The two cards are connected via a cross-over cable.
I haven't seen the problem when copying data from host1 to host2 - the
limiting factor is the PCMCIA interface on host2 (it's running at
about 55% interrupt). The problem does occur when copying from host2
to host1 - whichever is the server. I haven't tried FTP (neither
machine runs ftpd).
When viewed on host1, I see the following:
09:49:33.682213 host2.ssh > host1.2567: . 24789153:24790601(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075045> (DF) [tos 0x8]
09:49:33.682421 host1.2567 > host2.ssh: . ack 24790601 win 32580 <nop,nop,timestamp 251075045 355113> (DF) [tos 0x8]
09:49:33.683441 host2.ssh > host1.2567: . 24790601:24792049(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075045> (DF) [tos 0x8]
09:49:33.683806 host1.2567 > host2.ssh: . ack 24792049 win 33304 <nop,nop,timestamp 251075046 355114> (DF) [tos 0x8]
09:49:33.684802 host2.ssh > host1.2567: . 24792049:24793497(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075045> (DF) [tos 0x8]
09:49:33.686068 host2.ssh > host1.2567: . 24793497:24794945(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075045> (DF) [tos 0x8]
09:49:33.686265 host1.2567 > host2.ssh: . ack 24794945 win 32580 <nop,nop,timestamp 251075046 355114> (DF) [tos 0x8]
09:49:33.687624 host2.ssh > host1.2567: . 24794945:24796393(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075045> (DF) [tos 0x8]
09:49:33.688218 host1.2567 > host2.ssh: . ack 24796393 win 33304 <nop,nop,timestamp 251075046 355114> (DF) [tos 0x8]
09:49:33.688970 host2.ssh > host1.2567: . 24796393:24797841(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075045> (DF) [tos 0x8]
09:49:33.690104 host2.ssh > host1.2567: . 24797841:24799289(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075045> (DF) [tos 0x8]
09:49:33.690326 host1.2567 > host2.ssh: . ack 24799289 win 32580 <nop,nop,timestamp 251075046 355114> (DF) [tos 0x8]
09:49:35.611929 host2.ssh > host1.2567: . 24799289:24800737(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075046> (DF) [tos 0x8]
09:49:35.612361 host1.2567 > host2.ssh: . ack 24800737 win 33304 <nop,nop,timestamp 251075238 355114> (DF) [tos 0x8]
09:49:35.613166 host2.ssh > host1.2567: . 24800737:24802185(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075046> (DF) [tos 0x8]
09:49:35.614500 host2.ssh > host1.2567: . 24802185:24803633(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075046> (DF) [tos 0x8]
09:49:35.614682 host1.2567 > host2.ssh: . ack 24803633 win 32580 <nop,nop,timestamp 251075239 355114> (DF) [tos 0x8]
09:49:35.615725 host2.ssh > host1.2567: . 24803633:24805081(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075046> (DF) [tos 0x8]
When viewed on host2, I see the following:
09:49:33.806405 host2.ssh > host1.2567: . 24789153:24790601(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075045> (DF) [tos 0x8]
09:49:33.807222 host2.ssh > host1.2567: . 24790601:24792049(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075045> (DF) [tos 0x8]
09:49:33.808070 host2.ssh > host1.2567: . 24792049:24793497(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075045> (DF) [tos 0x8]
09:49:33.808887 host2.ssh > host1.2567: . 24793497:24794945(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075045> (DF) [tos 0x8]
09:49:33.810836 host1.2567 > host2.ssh: . ack 24790601 win 32580 <nop,nop,timestamp 251075045 355113> (DF) [tos 0x8]
09:49:33.810895 host1.2567 > host2.ssh: . ack 24792049 win 33304 <nop,nop,timestamp 251075046 355114> (DF) [tos 0x8]
09:49:33.811775 host2.ssh > host1.2567: . 24794945:24796393(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075045> (DF) [tos 0x8]
09:49:33.812590 host2.ssh > host1.2567: . 24796393:24797841(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075045> (DF) [tos 0x8]
09:49:33.813406 host2.ssh > host1.2567: . 24797841:24799289(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075045> (DF) [tos 0x8]
09:49:33.813567 host1.2567 > host2.ssh: . ack 24794945 win 32580 <nop,nop,timestamp 251075046 355114> (DF) [tos 0x8]
09:49:33.814882 host1.2567 > host2.ssh: . ack 24796393 win 33304 <nop,nop,timestamp 251075046 355114> (DF) [tos 0x8]
09:49:33.815121 host1.2567 > host2.ssh: . ack 24799289 win 32580 <nop,nop,timestamp 251075046 355114> (DF) [tos 0x8]
09:49:35.736124 host2.ssh > host1.2567: . 24799289:24800737(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075046> (DF) [tos 0x8]
09:49:35.736934 host2.ssh > host1.2567: . 24800737:24802185(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075046> (DF) [tos 0x8]
09:49:35.737741 host2.ssh > host1.2567: . 24802185:24803633(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075046> (DF) [tos 0x8]
09:49:35.738608 host2.ssh > host1.2567: . 24803633:24805081(1448) ack 512 win 33304 <nop,nop,timestamp 355114 251075046> (DF) [tos 0x8]
09:49:35.738675 host1.2567 > host2.ssh: . ack 24800737 win 33304 <nop,nop,timestamp 251075238 355114> (DF) [tos 0x8]
Note the two second gap. The last packet received by host2
acknowledges the last packet sent by host2, but host2 then
has a nap for 2 seconds before continuing.
Does anyone have any ideas?
Peter
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