The redundant Route Processors (RPs) have different memory configurations. To support the high availability feature, it is recommended that both RPs have the same memory configurations.
This issue is specific to MSFC2. It is not neccessary that the error message and the duplicate interface always occur together. If the ROM Monitor (ROMmon) version is not the minimum required to support the Cisco IOS for MSFC2, this causes the error message to be displayed, even if the memory configurations are physically correct between both RPs. This issue can also lead to duplicate or bogus Switched Virtual Interfaces (SVIs) or interface VLANs.
This is an example:
! interface Vlan24 ip address 10.24.24.254 255.255.255.0 ip helper-address 10.24.2.245 no ip redirects ! interface Vlan24 no ip address shutdown !
router#show ip interface brief
Interface IP-Address OK? Method Status Protocol Vlan24 10.24.24.254 YES manual up up Vlan24 unassigned YES unset administratively down down