netdev - Re: capturing VLAN

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Date:	Fri, 29 Feb 2008 16:45:20 +0100
From:	Pavel Krauz <krauz@...z.cz>
To:	netdev@...r.kernel.org
Subject: Re: capturing VLAN

>> Hi guys
>> as I see it, capturing packets with VLAN tag over PCAP is simply
>> broken on 2.6 kernel with the HW acceleration. Applications that need
>> unmodified packets over PCAP in promisc mode cannot work when VLAN
>> is present in the traffic.

> Older kernels (e.g. debian 2.6.18) had the problem that when you enable
> 802.1q VLAN support the acenic driver dropped the first vlan tag on a
> packet regardless if you enable vlans or not. If you recompile a kernel
> without 802.1q VLAN support all 802.1q tags should be in the pcap.

Unfortunately even when the CONFIG_VLAN_8021Q is undefined (no 
support for VLAN in kernel) I do not get the VLAN tags in PCAP for
NetXtreme II driver (I do not know about the Intel E1000 driver
which we also use). Even if it worked I do not think it solves the problem
-  you may need to connect the server over VLAN on different
(non monitoring) eth interface.

b.r.
Pavel
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