TCP packet out-of-order problem

[Lin Jui-Nan Eric]

Hello,

Yes, it's 1 now.

On Wed, Dec 31, 2008 at 6:49 PM, Václav Haisman <v.haisman at sh.cvut.cz> wrote:
> Lin Jui-Nan Eric wrote, On 30.12.2008 21:06:
>> Dear listers,
>>
>> We recently found our new FreeBSD server (located in some foreign
>> region) has poor network performance. After doing some tcpdump and
>> iperf testing, we found that out-of-order TCP packets are not inserted
>> into queue.
>>
>> This is an 100Mbps line, and TSO is disabled.
>>
>> % uname -a
>> FreeBSD bsd 7.1-RC2 FreeBSD 7.1-RC2 #2: Wed Dec 31 03:12:39 CST 2008
>>   root at bsd:/usr/obj/usr/src/sys/KERNEL  amd64
>>
>> % iperf -c 10.1.1.250
>> ------------------------------------------------------------
>> Client connecting to office, TCP port 5001
>> TCP window size: 3.07 MByte (default)
>> ------------------------------------------------------------
>> [  4] local 10.1.1.210 port 61488 connected with 10.1.1.250 port 5001
>> [ ID] Interval       Transfer     Bandwidth
>> [  4]  0.0-10.2 sec  5.74 MBytes  4.74 Mbits/sec
>>
>> 03:47:21.146397 IP 10.1.1.210.54919 > 10.1.1.250.5001: .
>> 159305:160753(1448) ack 1 win 1040 <nop,nop,timestamp 555928950
>> 3216612488>
>> 03:47:21.146409 IP 10.1.1.250.5001 > 10.1.1.210.54919: . ack 160753
>> win 12568 <nop,nop,timestamp 3216612488 555928950>
>> 03:47:21.146473 IP 10.1.1.210.54919 > 10.1.1.250.5001: .
>> 160753:162201(1448) ack 1 win 1040 <nop,nop,timestamp 555928950
>> 3216612488>
>> 03:47:21.146485 IP 10.1.1.250.5001 > 10.1.1.210.54919: . ack 162201
>> win 12568 <nop,nop,timestamp 3216612489 555928950>
>> 03:47:21.146972 IP 10.1.1.210.54919 > 10.1.1.250.5001: .
>> 163649:165097(1448) ack 1 win 1040 <nop,nop,timestamp 555928950
>> 3216612488>
>> 03:47:21.146983 IP 10.1.1.250.5001 > 10.1.1.210.54919: . ack 162201
>> win 12573 <nop,nop,timestamp 3216612489 555928950>
>> 03:47:21.146985 IP 10.1.1.210.54919 > 10.1.1.250.5001: .
>> 162201:163649(1448) ack 1 win 1040 <nop,nop,timestamp 555928950
>> 3216612488>
>> 03:47:21.146996 IP 10.1.1.250.5001 > 10.1.1.210.54919: . ack 163649
>> win 12568 <nop,nop,timestamp 3216612489 555928950>
>> 03:47:21.146998 IP 10.1.1.210.54919 > 10.1.1.250.5001: .
>> 165097:166545(1448) ack 1 win 1040 <nop,nop,timestamp 555928950
>> 3216612488>
>> 03:47:21.147006 IP 10.1.1.250.5001 > 10.1.1.210.54919: . ack 163649
>> win 12573 <nop,nop,timestamp 3216612489 555928950>
>> 03:47:21.147009 IP 10.1.1.210.54919 > 10.1.1.250.5001: .
>> 166545:167993(1448) ack 1 win 1040 <nop,nop,timestamp 555928950
>> 3216612488>
>> 03:47:21.147017 IP 10.1.1.250.5001 > 10.1.1.210.54919: . ack 163649
>> win 12573 <nop,nop,timestamp 3216612489 555928950>
>> 03:47:21.147019 IP 10.1.1.210.54919 > 10.1.1.250.5001: .
>> 167993:169441(1448) ack 1 win 1040 <nop,nop,timestamp 555928950
>> 3216612488>
>>
>> * You can see "ack 163649" repeating, but the packet is transmitted
>> before 163649:165097.
>>
>> % cat /etc/sysctl.conf
>> # $FreeBSD: src/etc/sysctl.conf,v 1.8 2003/03/13 18:43:50 mux Exp $
>> #
>> #  This file is read when going to multi-user and its contents piped thru
>> #  ``sysctl'' to adjust kernel values.  ``man 5 sysctl.conf'' for details.
>> #
>>
>> # Uncomment this to prevent users from seeing information about processes that
>> # are being run under another UID.
>> #security.bsd.see_other_uids=0
>> debug.bootverbose=1
>> kern.ipc.somaxconn=8192
>> kern.maxfiles=65536
>> kern.maxfilesperproc=32768
>> kern.maxprocperuid=65536
>> net.inet.ip.fastforwarding=1
>> net.inet.tcp.delayed_ack=0
>> vm.pmap.shpgperproc=2000
>> kern.ipc.maxsockbuf=8388608
>> net.inet.tcp.sendspace=3217968
>> net.inet.tcp.recvspace=3217968
>>
>> Is our configuration wrong? Or it is an known bug? I have searched
>> stable & net list, but found no similar discussion.
>> Thank you all in advance!
> Do you have net.inet.tcp.sack.enable=1?
>
> --
> VH
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