From: "Ilpo Järvinen" <ilpo.jarvinen@helsinki.fi>
To: Russell King <rmk@arm.linux.org.uk>
Cc: Netdev <netdev@vger.kernel.org>,
Ben Hutchings <bhutchings@solarflare.com>
Subject: Re: 2.6.27.8 (+the idr fix) TCP Ack issue
Date: Wed, 31 Dec 2008 22:20:46 +0200 (EET) [thread overview]
Message-ID: <Pine.LNX.4.64.0812312215590.3247@wrl-59.cs.helsinki.fi> (raw)
In-Reply-To: <20081231171016.GA1901@flint.arm.linux.org.uk>
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On Wed, 31 Dec 2008, Russell King wrote:
> On Wed, Dec 31, 2008 at 12:38:24PM +0200, Ilpo Järvinen wrote:
> > If you have the dump still at handy, could you add couple of -v -v for
> > tcpdump. It could be that the peer is using bogus seqnos in the
> > duplicate ACK but by default that's not visible for zero sized segs
> > (checked in tcp_validate_incoming in the 2.6.28.7 kernel).
>
> Is "seqno" another name for the IP ID field?
No, it's a sequence number, there are two sequence number spaces per flow,
one for each direction (each has a corresponding field in the tcp header).
For pure ACKs tcpdump won't show the sequence number by default even
though it's still there...
With tcpdump -n -v -v I get this for pure acks:
...: ., cksum 0x43c0 (correct), 671:671(0) ack 14649 win 36500
That 671:671(0) won't be visible with smaller verbosity.
--
i.
next prev parent reply other threads:[~2008-12-31 20:20 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-30 19:58 2.6.27.8 (+the idr fix) TCP Ack issue Russell King
2008-12-31 10:38 ` Ilpo Järvinen
2008-12-31 17:10 ` Russell King
2008-12-31 20:20 ` Ilpo Järvinen [this message]
2009-01-02 14:26 ` Russell King
2009-01-02 21:34 ` David Miller
2009-01-02 22:02 ` Russell King
2009-01-02 8:43 ` Herbert Xu
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