mario.verbelen.org

When I rebooted a xen guest I had no network anymore
this was strange, all the other guests had no problem with networking

After checking some commands I saw that the bridge has a weard problem(lenny/xen/bridge)

dummy0
 bridge id		8000.065a2bb7ed3a
 designated root	8000.065a2bb7ed3a
 root port		   0			path cost		   0
 max age		   0.00			bridge max age		   0.00
 hello time		   2.00			bridge hello time	   2.00
 forward delay		-150503672.24			bridge forward delay	-150503672.24
 ageing time		 300.01
 hello timer		   0.98			tcn timer		   0.00
 topology change timer	-143192091.79			gc timer		-156558985.99
 flags			TOPOLOGY_CHANGE TOPOLOGY_CHANGE_DETECTED 
====snip other interfaces===
vif51.0 (10)
 port id		800a			state		      listening
 designated root	8000.065a2bb7ed3a	path cost		 100
 designated bridge	8000.065a2bb7ed3a	message age timer	   0.00
 designated port	800a			forward delay timer	-150504113.11
 designated cost	   0			hold timer		   0.00
 flags			

vif51.1 (11)
 port id		800b			state		      listening
 designated root	8000.065a2bb7ed3a	path cost		 100
 designated bridge	8000.065a2bb7ed3a	message age timer	   0.00
 designated port	800b			forward delay timer	-150504113.11
 designated cost	   0			hold timer		   0.00
 flags

It looks like the bridge has lost some counters

off-course rebooting is no option with many other production guests
I guess that reloading the bridge module will fix this to, but no option ...

I found out that resetting the Forward delay counter can help here
after resetting I reconnect the interfaces and ... here we are again

brctl setfd dummy0 5
brctl delif dummy0 vif51.0
brctl delif dummy0 vif51.1
brctl addif dummy0 vif51.0
brctl addif dummy0 vif51.1

brctl showstp dummy0
dummy0
 bridge id		8000.065a2bb7ed3a
 designated root	8000.065a2bb7ed3a
 root port		   0			path cost		   0
 max age		   0.00			bridge max age		   0.00
 hello time		   2.00			bridge hello time	   2.00
 forward delay		   5.00			bridge forward delay	   5.00
 ageing time		 300.01
 hello timer		   1.15			tcn timer		   0.00
 topology change timer	   0.00			gc timer		-156559706.11
 flags			

vif51.0 (10)
 port id		800a			state		     forwarding
 designated root	8000.065a2bb7ed3a	path cost		 100
 designated bridge	8000.065a2bb7ed3a	message age timer	   0.00
 designated port	800a			forward delay timer	   0.00
 designated cost	   0			hold timer		   0.00
 flags			

vif51.1 (11)
 port id		800b			state		     forwarding
 designated root	8000.065a2bb7ed3a	path cost		 100
 designated bridge	8000.065a2bb7ed3a	message age timer	   0.00
 designated port	800b			forward delay timer	   0.00
 designated cost	   0			hold timer		   0.00
 flags