[Bridge] Re: tg3 bridge problems

Neil Horman nhorman at redhat.com
Mon Jan 10 07:05:56 PST 2005

Gergely Madarasz wrote:
> Hello,
> 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? 
> Greg
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It looks to me like either order should work just fine, as long as the 
IFF_PROMISC flag isn't cleared when you bring up the interface.  Is 
IF_PROMISC clear in ifconfig after you issue your ifconfig eth0 up command?


  *Neil Horman
  *Software Engineer
  *Red Hat, Inc.
  *nhorman at redhat.com
  *gpg keyid: 1024D / 0x92A74FA1

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