[Bridge] IP address on physcial interface instead of bridge interface?

[Joakim Tjernlund]

Stephen Hemminger <shemminger at linux-foundation.org> wrote on 2010/03/28 05:17:52:
>
> On Sat, 27 Mar 2010 11:50:23 +0100
> Joakim Tjernlund <joakim.tjernlund at transmode.se> wrote:
>
> > "richardvoigt at gmail.com" <richardvoigt at gmail.com> wrote on 2010/03/26 22:42:52:
> > >
> > > On Fri, Mar 26, 2010 at 3:48 PM, Joakim Tjernlund
> > > <joakim.tjernlund at transmode.se> wrote:
> > > >
> > > >
> > > > Nicolas de Pesloüan <nicolas.2p.debian at free.fr> wrote on 2010/03/26 21:39:33:
> > > >
> > > >> From: Nicolas de Pesloüan <nicolas.2p.debian at free.fr>
> > > >> To: Joakim Tjernlund <joakim.tjernlund at transmode.se>
> > > >> Cc: bridge at lists.linux-foundation.org
> > > >> Date: 2010/03/26 21:39
> > > >> Subject: Re: [Bridge] IP address on physcial interface instead of
> bridge interface?
> > > >>
> > > >> Joakim Tjernlund wrote:
> > > >>
> > > >> > Figure a small picture will help so here it is:
> > > >> >
> > > >> > Before adding eth0 to br0:
> > > >> > eth0    br0
> > > >> >  |
> > > >> >  |
> > > >> > HW controller
> > > >> >
> > > >> > after adding eth0 to br0:
> > > >> > eth0
> > > >> >   \
> > > >> >    \
> > > >> >      br0
> > > >> >    /
> > > >> >   /
> > > >> > HW controller
> > > >>
> > > >> I don't understand your ascii art. What is HW controller ? eth0 is an hardware
> > > >> controller !?
> > > >>
> > > >>    Nicolas.
> > > >
> > > > eth0 is the I/F IP stack will see/use. HW controller is the ethernet HW
> controller,
> > > > the PCI HW if you like.
> > >
> > > No!
> > >
> > > br0 does NOT sit between eth0 and the NIC.  eth0 still represents the
> > > NIC.  br0 sits on top, and represents the combined traffic stream from
> > > eth0 and all other bridge ports.  By adding eth0 to the bridge, you
> > > told it to forward all incoming frames to br0 which is the next higher
> > > layer in the virtual interface hierarchy.
> >
> > Of course the above isn't how the bridge works today. I was trying
> > to described a new feature which would let me use eth0 as my normal
> > IP interface even after it was added to the bridge.
> > The above would emulate connecting the eth0 I/F to an external HW bridge.
>
> If you read the network receive code path in the kernel, you
> will see that there is a special hook used. Basically,
>
>   if received_interface_is_part_of_bridge(incoming_interface)
>   then process_bridged_packet(packet)
>
> Then bridge looks at packet and decides whether it is local or forwarded.
> The problem is with your application if it wants to use eth0 directly.

Right, what seems to be missing is at similar hook for TX path?
If a TX hook existed(I am guessing there isn't one) then it would
be relative simple to redirect pks from the IP stack to the bride
instead instead of the HW driver?

 Jocke