From: "Guo-Fu Tseng" <cooldavid@cooldavid.org>
To: David Miller <davem@davemloft.net>, jengelh@medozas.de
Cc: netdev@vger.kernel.org
Subject: Re: jme: UDP checksum error, and lots of them
Date: Thu, 2 Dec 2010 12:33:01 +0800 [thread overview]
Message-ID: <20101202042820.M98672@cooldavid.org> (raw)
In-Reply-To: <20101201.200935.71110482.davem@davemloft.net>
On Wed, 01 Dec 2010 20:09:35 -0800 (PST), David Miller wrote
> From: Jan Engelhardt <jengelh@medozas.de>
> Date: Thu, 2 Dec 2010 04:39:34 +0100 (CET)
>
> > Why does the JME driver care so much about this that it needs to print
> > this for every packet? It does not look like it has any offloading
> > features.
>
> Well I'm glad it let us know about the bad checksum which would otherwise
> have been unnoticed.
>
> Please try to pinpoint why the checksum is bad, because it seems that
> tcpdump agrees with the driver. Perhaps it's some side effect of how
> vpnc uses TUN/TAP, or something like that.
>
> Seeing the bad checksum even in tcpdump, and then seeing proper replies
> going back, that is very suspicious and should be looked into.
> --
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Indeed... It is suspicious to reply proper response against the packet
with bad checksum.
Jan: Would you try to turn off the rx-checksum offloading with ethtool
and see how it goes?
I suspect that there might be some the HW-Checksum behavior error.
ex: Replaced the UDP checksum field while it's all zero(no need to checksum)
Guo-Fu Tseng
next prev parent reply other threads:[~2010-12-02 4:33 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-02 3:39 jme: UDP checksum error, and lots of them Jan Engelhardt
2010-12-02 3:53 ` Guo-Fu Tseng
2010-12-02 4:09 ` David Miller
2010-12-02 4:33 ` Guo-Fu Tseng [this message]
2010-12-02 5:59 ` David Miller
2010-12-02 23:15 ` Francois Romieu
2010-12-02 23:54 ` Jan Engelhardt
2010-12-03 23:02 ` Francois Romieu
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