On Thu, 07 Jan 2010 17:57:16 -0600
Andrew <amckay at iders.ca> wrote:
> Hey guys,
>
> I'm working with a bridge I set up on Linux 2.6.30.9. I have two
boards
> connected and created a redundant connection between them. Basic set up
is:
>
> brctl addbr br0
> brctl addif br0 vlan1
> brctl addif br0 vlan2
> brctl stp br0 on
>
> Then I bring up the interfaces. Everything seems to be fine. Root
> bridge is negotiated properly and leaves both interfaces in forwarding
> mode. The other bridge leaves one port in forwarding and puts the other
> in blocking mode. However after several seconds a message is printed on
> my terminal saying that vlan2 lost it's neighbor and goes through the
> listening, learning and then forwarding states. It then quickly flips
> back to blocking mode. Is this normal behavior for STP on Linux
> 2.6.30.9? Or do I have something else going on here?
>
> net/bridge/br_stp.c:36 br0: port 2(vlan2) entering blocking state
> br0: neighbor 8000.3a:1f:34:08:54:56 lost on port 2(vlan2)
> net/bridge/br_stp.c:36 br0: port 2(vlan2) entering listening state
> net/bridge/br_stp.c:36 br0: port 2(vlan2) entering learning state
> br0: topology change detected, sending tcn bpdu
> net/bridge/br_stp.c:36 br0: port 2(vlan2) entering forwarding state
> br0: topology change detected, sending tcn bpdu
> net/bridge/br_stp.c:36 br0: port 2(vlan2) entering blocking state
>
> If there's any further information you need, let me know.
Bridging two vlan's with STP can be problematic because many
switches implement STP on a physical interface (see vlan Spanning
Tree). Also, make sure that STP packets aren't being blocked by
some firewall rule.