I have this setup:
a 2621 with its fa0/0 connected to a 2912(a) and its fa0/1 to another 2912(b). The 2 2912 are connected using a crossover cable. I enable IRB on 2621 and make it as root of vlan1. A laptop is attached to 2912a to ping the router. Everything is fine when all cables are connected. But if the link from 2912a to 2621 is disconnected, the ping to the router cannot be resumed. I suspect there is something wrong with the spanning tree since I found ALL connected ports are in the state of forwarding(before disconnecting the link from 2912a to 2621). There should be a blocked port on one of the 2912 but in this case no.
Is there something wrong with the config, or there is no way to make this work? Actually I want to use both ethernet ports on 2621 for resiliency.
2621 ver: 12.1(20)
2912 ver: 12.0(5)WC8
2621 config:
-------------
bridge irb
!
!
interface FastEthernet0/0
no ip address
speed 100
full-duplex
bridge-group 1
!
interface FastEthernet0/1
no ip address
speed 100
full-duplex
bridge-group 1
!
interface BVI1
ip address 10.1.1.1 255.0.0.0
!
ip classless
no ip http server
!
bridge 1 protocol ieee
bridge 1 route ip
bridge 1 priority 1
!
