Message-ID: <353568DCBAE06148B70767C1B1A93E625EAB66@post.pc.aspectgroup.co.uk>
From: Richard Underwood <richard@aspectgroup.co.uk>
To: "'David S. Miller'" <davem@redhat.com>, Bill Davidsen <davidsen@tmr.com>
Cc: dang@fprintf.net, alan@lxorguk.ukuu.org.uk,
       Richard Underwood <richard@aspectgroup.co.uk>, skraw@ithnet.com,
       willy@w.ods.org, carlosev@newipnet.com, lamont@scriptkiddie.org,
       bloemsaa@xs4all.nl, marcelo@conectiva.com.br, netdev@oss.sgi.com,
       linux-net@vger.kernel.org, layes@loran.com, torvalds@osdl.org,
       linux-kernel@vger.kernel.org
Subject: RE: [2.4 PATCH] bugfix: ARP respond on all devices
Date: Wed, 20 Aug 2003 21:10:23 +0100
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David S. Miller wrote:
> 
> BTW, another thing which makes the source address selection for
> outgoing ARPs a real touchy area is the following.  Some weird
> configurations actually respond with different ARP answers based upon
> the source address in the ARP request.  You can ask Julian Anastasov
> about such (arguably pathological) setups.
> 
	*smirk* How horrible. I'm not sure you should be proud of supporting
this, and certainly not proud of only half-supporting it. It wouldn't work
reliably as things are now as packets will always follow the ARP reply
generated by the very first packet.

	If you want to facilitate this sort of network, you'd need to cache
an ARP reply for an IP number against BOTH the Interface AND the interface
address used as the source of the ARP request. Only then could you guarantee
that packets go to the correct IP number out of the correct interface based
on their source address.

		Richard
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