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Re: r8169 802.1q/MTU bug

To: Jon Mason <jdmason@xxxxxxxxxx>
Subject: Re: r8169 802.1q/MTU bug
From: Francois Romieu <romieu@xxxxxxxxxxxxx>
Date: Wed, 1 Jun 2005 01:44:58 +0200
Cc: James Harr <james@xxxxxxxxxxx>, netdev@xxxxxxxxxxx
In-reply-to: <200505311820.41469.jdmason@us.ibm.com>
References: <20050530071148.GB1514@electric-eye.fr.zoreil.com> <200505301927.26110.james@grickle.org> <200505311820.41469.jdmason@us.ibm.com>
Sender: netdev-bounce@xxxxxxxxxxx
User-agent: Mutt/1.4.1i
Jon Mason <jdmason@xxxxxxxxxx> :
[...]
> I wonder if this is related to the adapter breaking large frames into
> multiple descriptors.  On normal (non-VLAN) frames, this happens at MTU
> 8169. I wonder if enabling VLAN and jumbo frames (a combination I never
> tried) brings down the threshold to MTU 7200.  

Testing suggests that there is at least a size filtering issue (fixed
in netdev-2.6.git but not in 2.6.11.xx nor in 2.6.12-rc). It is unrelated
to hardware vlan support and happens a few bytes above the MTU on the vlan
device (which is set to the same value as the adapter). Of course different
issues could hide in the dark.

--
Ueimor

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