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From: Simon Horman <horms@verge•net.au>
To: David Miller <davem@davemloft•net>
Cc: mst@redhat•com, eric.dumazet@gmail•com, netdev@vger•kernel.org,
	johann.baudy@gnu-log•net
Subject: Re: [PATCH] af_packet: account for VLAN when checking packet size
Date: Fri, 22 Oct 2010 10:41:26 +0200	[thread overview]
Message-ID: <20101022084052.GA2118@verge.net.au> (raw)
In-Reply-To: <20101012.104032.71103852.davem@davemloft.net>

On Tue, Oct 12, 2010 at 10:40:32AM -0700, David Miller wrote:
> From: "Michael S. Tsirkin" <mst@redhat•com>
> Date: Tue, 12 Oct 2010 19:19:41 +0200
> 
> > Yes, like eth_type_trans does I guess.  I think we had a similar
> > discussion already:
> > 
> > http://lists.openwall.net/netdev/2010/01/06/38
> > 
> > Summary: if we want to make the protocol field have the correct
> > value for this case we need to make it work for other
> > transports not just for ethernet.
> 
> Right, so for now we should just allow 4-byte larger
> than MTU TX packets, as long as the device is ethernet
> and can handle VLANs properly.

Incidently, I believe that this problem will only become more acute
and complex if support for 802.1ad (Provider Bridges, aka Q-in-Q),
802.1ah (Provider Backbone Bridges, aka MAC-in-MAC) or other standards
which further extend the maximum frame size.

Dave, you were mentioning to me the other day that the kernel
already supports some notion of Q-in-Q (though its not 802.1ad).
Does the current implementation allow for frames > 1504 bytes?
Is that a complication to the change proposed here?


  reply	other threads:[~2010-10-23  1:27 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-30 19:24 sending VLAN packets via packet_mmap Phil Sutter
2010-10-07  6:53 ` David Miller
2010-10-11 13:15   ` Phil Sutter
2010-10-11 13:25     ` [PATCH] af_packet: account for VLAN when checking packet size Phil Sutter
2010-10-11 14:03       ` Eric Dumazet
2010-10-11 16:01         ` David Miller
2010-10-11 17:29           ` Phil Sutter
2010-10-12 17:19             ` Michael S. Tsirkin
2010-10-12 17:40               ` David Miller
2010-10-22  8:41                 ` Simon Horman [this message]
2010-10-27 15:48                   ` David Miller

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