Re: [PATCH] [bridge] Add split horizon

["richardvoigt@xxxxxxxxx" <richardvoigt@xxxxxxxxx>]

On Sat, Jun 13, 2009 at 10:03 AM, Joakim
Tjernlund<joakim.tjernlund@xxxxxxxxxxxx> wrote:
> Benny Amorsen <benny+usenet@xxxxxxxxxx> wrote on 13/06/2009 01:58:53:
>>
>> Joakim Tjernlund <Joakim.Tjernlund@xxxxxxxxxxxx> writes:
>>
>> > Currently the bridge does not impl. split horizon which will easily
>> > cause loops when 2 or more VLANs are added from the same physical interface.
>>
>> Why would they cause loops? If your topology isn't loop free, run
>> spanning tree in the VLAN's. Yet another thing most hardware switches
>> can't do, incidentally.
>
> ehh, connect two Linux bridges that have 2 VLANs in common on the interswitch connection.

For example, here is a configuration that meets your problem
description and has no loops:

host A eth0 connected to hostB eth0

host A:
brctl add br0
brctl addif br0 eth0.1
brctl addif br0 eth1
brctl add br1
brctl addif br1 eth0.2
brctl addif br1 eth2

host B:
brctl add br0
brctl addif br0 eth0.1
brctl addif br0 wlan0.1
brctl add br1
brctl addif br1 eth0.2
brctl addif br1 wlan0.2

Let's compare this to your complaint:
Two Linux hosts.... check
Two VLANs in common.... check
Both VLANs on the inter-switch connection.... check

Nope, there are no loops.

You need to stop calling "a machine running bridging" a "Linux
bridge".  A "bridge", in Linux, is a virtual interface inside a
machine with the bridging module loaded.  There can be more than zero,
one, or multiple bridges in a single Linux machine.  I think that when
you understand that, all your problems will go away with a simpler
configuration and no changes to the Linux kernel.



> What happens?
>
>  Jocke
>
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