netdev - Re: How to use gretap with bridge?

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Message-ID: <20091029234756.GA1595@gondor.apana.org.au>
Date:	Thu, 29 Oct 2009 19:47:56 -0400
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	"Neulinger, Nathan" <nneul@....edu>
Cc:	Stephen Hemminger <shemminger@...tta.com>, netdev@...r.kernel.org
Subject: Re: How to use gretap with bridge?

On Thu, Oct 29, 2009 at 05:04:02PM -0500, Neulinger, Nathan wrote:
> Now I see it - Stephen actually had it right on - the problem is that
> the gre tunnel is creating a MAC address on the fly based on the tunnel
> endpoint ip address, so if the tunnel endpoint address starts with an
> odd number, it hits the multicast check in the bridging code. (I'm sure
> that's what he meant and I just missed it entirely.)
> 
> Simplest option would probably be to just mask off the first octet with
> 0xFD or using the ip as the last four octets of the mac instead of the
> first four.

This looks like a bug in either iproute or the kernel.  It's
not supposed to set a MAC address unless the user specifically
gives one.  If one is not given the kernel will generate a valid
MAC address.

Cheers,
-- 
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Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
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