On 2011-07-06 23:48:18 (+0800), jiangtao.jit [off-list ref] wrote:

5.brctl show         like 
bridge name     bridge id               STP enabled     interfaces
br0                                                no              eth0

You've got a loop in your Ethernet network and spanning tree is
disabled.
The surprising bit is that you manage to get any packets through at all.

Ethernet packets don't have a TTL field, so if they end up in a loop
(for example br0 -> eth0 -> LAN -> eth1 -> br0 -> ...) they just keep
getting repeated.

brctl br0 stp on should fix your network.

I suspect you're trying to do bonding though, which (as far as I know,
having never played with it myself) is configured completely differently 
and might require support from the switch.

Regards,
Kristof