[Bridge] Re: tg3 bridge problems

Gergely Madarasz gorgo at broadband.hu
Mon Jan 10 11:11:33 PST 2005

On Mon, Jan 10, 2005 at 12:40:57PM -0500, Neil Horman wrote:
> Gergely Madarasz wrote:
> >On Mon, Jan 10, 2005 at 11:04:55AM -0500, Neil Horman wrote:
> >
> >>Strange.  My concern was that the tg3 interface has its hardware reset 
> >>whenever its set to be up, and part of that is a resetting of its 
> >>receive mode.  If for some reason IFF_PROMISC was cleared after you set 
> >>it using brctl, the interface might be taken out of promisc mode.  Do 
> >>you have any iptables rules running that might drop bpdus?
> >
> >
> >No iptables rules az all. Btw iptables wouldn't prevent tcpdump from
> >seeing the packets, would it?
> >Could it be that the driver perhaps has a problem setting promisc mode
> >when resetting the hardware?
> >
> Not really sure about this.  One experiment is worth a thousand guesses 
> I suppose.......  I'll try and let you know. :)

I did some other checks, like adding an explicit ifconfig eth0 promisc,
then looking at tcpdump output - I didn't see any stray packets like I
usually do, just ethernet broadcasts and unicasts to my mac, this also
points to a problem that the ethernet interface is actually not in
promisc, while the driver thinks it is.

And it is probably not a driver-only issue. I've got older machines with
tg3 running fine with bridge (with an older tg3 driver), and eth1 on the
same machine also runs fine. On another machine I tested today, an IBM
x326, the same thing happens - eth0 broken, eth1 fine. Would access to one
of these machines help? :)


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