For the impatient – bug id 5572.
A colleague called the other day – one of our machines had rebooted, and quite a number of network interfaces were not working. This particular machine has quite a number of vlans connected to it – most of them can’t work. The primary interface (eth0), still works fine; only eth0.xxx interfaces were affected.
Tcpdump shows that the arp requests were being made to the vlan interfaces, and replies were sent. However, the replies were not getting to other machines. After quite some troubleshooting, we decided to downgrade the kernel. That fixed the problem!
Seems like a bug has crept into tg3 kernel module in the 2.6.18-308 kernel. Hope this helps someone.