From: David Miller <davem@davemloft.net>
To: nhorman@tuxdriver.com
Cc: netdev@vger.kernel.org, ilpo.jarvinen@helsinki.fi
Subject: Re: BSD 4.2 style TCP keepalives
Date: Fri, 08 Jan 2010 17:41:38 -0800 (PST) [thread overview]
Message-ID: <20100108.174138.193059500.davem@davemloft.net> (raw)
In-Reply-To: <20100109012227.GA2762@localhost.localdomain>
From: Neil Horman <nhorman@tuxdriver.com>
Date: Fri, 8 Jan 2010 20:22:27 -0500
> I'm trying to do some independent computation on it, but its looking
> like this may have been a combination of old software (win2k) and a
> bad corner case in hardware. I think the reporter has a NIC that
> doesn't do TCO properly on these old style keepalives, which would
> explain why it wasn't reproducable outside of the reporters
> environment. I'm trying to figure out which card/hw revision of NIC
> they were using. It might be worth coding an errata check into the
> appropriate driver if this all turns out to be accurate to disable
> TCO affectecd hw.
I think it's not a hardware bug, because there isn't anything
interesting about these packets from a checksumming perspective.
It's just a normal 1-byte TCP data frame as far as the card is
concerned.
Rather, I think when checksum offloading, win2k doesn't set the
internal packet state correctly for such probe packets such that the
card is told to checksum the frame.
Ie. a win2k TCP bug and nothing to do with the card or it's driver.
prev parent reply other threads:[~2010-01-09 1:41 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-06 0:39 BSD 4.2 style TCP keepalives David Miller
2010-01-06 2:07 ` Neil Horman
2010-01-06 3:59 ` David Miller
2010-01-06 17:21 ` Rick Jones
2010-01-06 20:50 ` Neil Horman
2010-01-06 8:23 ` David Miller
2010-01-06 23:04 ` David Miller
2010-01-07 0:14 ` David Miller
2010-01-07 3:21 ` David Miller
2010-01-07 3:36 ` David Miller
2010-01-07 0:34 ` Ilpo Järvinen
2010-01-07 0:59 ` David Miller
2010-01-07 7:55 ` Ilpo Järvinen
2010-01-08 12:40 ` Neil Horman
2010-01-08 21:21 ` David Miller
2010-01-09 1:22 ` Neil Horman
2010-01-09 1:41 ` David Miller [this message]
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