Subject: Re: [RFC] gre: transparent ethernet bridging

From: Philip Craig <[email-masked]>
Date: Thu, 03 Aug 2006 11:33:25 +1000

Lennert Buytenhek wrote:
> On Mon, Jul 31, 2006 at 10:08:22PM -0700, Stephen Hemminger wrote:
> 
>>>> Why not use existing bridge code?
>>> It does use the existing bridge code.  Perhaps the name is misleading.
>>> All it does is encapsulate the full ethernet header in a gre packet,
>>> rather than only layer 3.  That is, currently gre uses ARPHRD_IPGRE,
>>> but bridging requires ARPHRD_ETHER.
>> I am not against making the bridge code smarter to handle other
>> encapsulation.
> 
> What if you want to run ethernet directly over a GRE tunnel, without
> using bridging?

But on the other hand, this method allows you to send both ethernet
and non-ethernet traffic over the same GRE tunnel.  Is that useful?
Actually, this feature is what makes the handling of the LLC_SAP_BSPAN
packets simple.

The patch to bridging is a lot cleaner than the patch to GRE, and it
also sidesteps the userspace configuration issues, so I don't want to
go back to modifying the GRE device.

Both could be achieved by creating a new virtual device that sits
between GRE and bridging.