We have been using the 'interface bvi' method to increase redundancy to 2800 series routers installed behind firewalls, so that each LAN interface on the router can connect to a different switch <same vlan of course>, which are then connected to the Primary and Backup firewalls in a redundant pair. We are moving on to the 3900 and 2900 series routers for the same application, but have found that they might work for a short time (180seconds/3 minutes); fail, and not come back. The testing I am doing just involves pings, but the end result is that the physical interface that is tied via the bridge group to the BVI interface shows no increase in the inbound packet count. I first suspected this was an issue with the 3560 switch that the test routers were connected to, but the same set up, same 3560 switch, with a 2811 router still works great. BTW, our production deployments of this technology have involved a pair of 5510 FW; pair of 2960 switches, and 28xx routers. Here is the partial config I am running on a 2911 that is having problems:
bridge 129 protocol ieee
bridge 129 route ip
ip address 10.19.129.204 255.255.255.0
As mentioned previously, I am testing this with pings sourced from within the same subnet. Works for a period of time - about 3 minutes - then stops. Deeper inspection show that the 'show interface F0/0' packets input line has stopped incrementing.
I appreciate in advance any suggestions you might have for this situation.