STP on Linux 2.6.30.9

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.

Andrew McKay
Iders Inc.

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.