[Bridge] tg3 bridge problems

Gergely Madarasz gorgo at broadband.hu
Mon Jan 10 06:06:38 PST 2005


I've got a very strange problem. Lately I've been setting up my linux
servers for network (layer2) redundancy with a bridge interface containing
two ethernet interfaces connecting to two switches. So far I didn't have
any problems with it, but now a very strange thing happens with a new
server I'm installing. The server is an ibm x346 having two onboard
BCM5721 cards, the switches are cisco 3550, and I've tested with kernel
versions 2.6.10 and 2.4.28.

The bpdu's from the cisco switches simply cannot be seen on the server,
causing loops in l2 traffic. I've tested with sticking a hub between the
c3550 and the server, the switch sends out the bpdu's, but they are not
seen by linux (running tethereal). This happens only on eth0, on eth1
everything seems fine. Any IP traffic on eth0 goes through, no packet
loss, no errors.

And something even more strange: if I do an 
ifconfig eth0 0 up; brctl addif br0 eth0; 
it seems to be working fine, if I do it the other way
round, then the bpdu's sent by the switches are lost somewhere.

Considering all these, the problem seems to me a strange interaction
between the bridge driver, the tg3 driver and the hardware in question. 

Any ideas? 


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