From: Arnd Hannemann <hannemann@nets•rwth-aachen.de>
To: Andrew Morton <akpm@linux-foundation•org>
Cc: netdev@vger•kernel.org, bugzilla-daemon@bugzilla•kernel.org,
bugme-daemon@bugzilla•kernel.org, jasen@treshna•com
Subject: Re: [Bugme-new] [Bug 15571] New: TCP madness - some packets are shunned.
Date: Thu, 25 Mar 2010 16:34:25 +0100 [thread overview]
Message-ID: <4BAB8281.8000905@nets.rwth-aachen.de> (raw)
In-Reply-To: <20100322143711.b78c7a93.akpm@linux-foundation.org>
Am 22.03.2010 22:37, schrieb Andrew Morton:
>
> (switched to email. Please respond via emailed reply-to-all, not via the
> bugzilla web interface).
>
> On Thu, 18 Mar 2010 02:46:29 GMT
> bugzilla-daemon@bugzilla•kernel.org wrote:
>
>> http://bugzilla.kernel.org/show_bug.cgi?id=15571
>>
>> URL: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=53646
>> 2
>> Summary: TCP madness - some packets are shunned.
>> Product: Networking
>> Version: 2.5
>> Kernel Version: 2.6.30
>> Platform: All
>> OS/Version: Linux
>> Tree: Mainline
>> Status: NEW
>> Severity: normal
>> Priority: P1
>> Component: Other
>> AssignedTo: acme@ghostprotocols•net
>> ReportedBy: jasen@treshna•com
>> Regression: No
>>
>>
>> The host http://www.cv-it.com is virtually unreachable with kernel 2.6.26
>> (and later) slow with kernel 2.6.18 and just fine with windows XP.
>>
>> I used telnet to port 80 for testing.
>>
>> it seems to be a TCP issue, as the having the XP machine behind a linux based
>> iptables firewall pc causes no problems, but telnet from the firewall pc itself
>> to port 80 on www.cv-it.com does not work
For me it seems to be the host is messing up with the window scale option.
Although it claims to support window scaling:
16:23:17.466592 IP x.x.x.x.51151 > 121.199.32.220.80: Flags [S], seq 2159265664, win 5840, options [mss 1460,sackOK,TS val 8382141 ecr 0,nop,wscale 7], length 0
16:23:17.761697 IP 121.199.32.220.80 > x.x.x.x.51151: Flags [S.], seq 3910885479, ack 2159265665, win 65535, options [mss 1448,sackOK,nop,nop,nop,nop,nop,nop,nop,nop,nop,nop,nop,wscale 8], length 0
My host (linux 2.6.32) is offering a window of 5888 (46<<7):
16:23:17.761740 IP x.x.x.x.51151 > 121.199.32.220.80: Flags [.], ack 1, win 46, length 0
And cv-it.com seems to think there is only a window of 46 ignoring the previously negotiated window scaling:
16:23:23.066318 IP 121.199.32.220.80 > x.x.x.x.51151: Flags [.], seq 1:47, ack 112, win 65160, length 46
You can disable window scaling with:
sysctl -w "net.ipv4.tcp_window_scaling=0"
Best regards,
Arnd
next prev parent reply other threads:[~2010-03-25 15:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-15571-10286@http.bugzilla.kernel.org/>
2010-03-22 21:37 ` [Bugme-new] [Bug 15571] New: TCP madness - some packets are shunned Andrew Morton
2010-03-25 15:34 ` Arnd Hannemann [this message]
[not found] ` <20100326053151.GA23938@treshna.com>
2010-03-26 8:41 ` Arnd Hannemann
2010-03-28 4:26 ` Stephen Hemminger
2010-03-30 21:08 ` Jasen Betts
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