netdev - Re: [PATCH 1/2] NET: Re-add VLAN tag for devices incapable of keeping it

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Date:	Tue, 06 Nov 2007 10:56:45 -0800
From:	Ben Greear <greearb@...delatech.com>
To:	Krzysztof Halasa <khc@...waw.pl>
CC:	Patrick McHardy <kaber@...sh.net>,
	David Miller <davem@...emloft.net>,
	djohnson+linux-kernel@...starentnetworks.com,
	jes@...ined-monkey.org, mchan@...adcom.com, ram.vepa@...erion.com,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	bguo@...starentnetworks.com
Subject: Re: [PATCH 1/2] NET: Re-add VLAN tag for devices incapable of keeping
 it

Krzysztof Halasa wrote:
> Patrick McHardy <kaber@...sh.net> writes:
> 
>> I think there is one more case that matters, which is briding
>> from a device with VLAN stripping for a VLAN not configured
>> locally. The tag will be stripped and will be lost for forwarded
>> packets.
> 
> I think we should drop such packets on RX. Anyway we shouldn't
> forward them.

Bridging eth0 to eth1 should not pay attention to VLAN tags
at all (if the pkt comes in on VLAN 7, it should go out on VLAN 7),
in my opinion.  If the NIC is stripping the VLAN header, then this
cannot work unless something re-builds the VLAN header.  If the stripped
VLAN header is placed into the skb, then any code that does need to
rebuild it can do so.  It may be less efficient, but users can just
not use that NIC hardware for high-end solutions, and at any rate,
less efficient is better than broken.

Ben

-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com

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