For reasons beyond the scope of the following discussion, I find myself in a situaltion where I need to think about using MPLS to backup a carrier ethernet solution that we have between two sites. Please see attached for the current configuration (left) and the target configuration (right).
The current configuration is really quite simple -- we have a 1Gbps L2 carrier ethernet solution in place that is connected to 1 x 2960X switch in each of the two sites. The VLAN 100 is defined on this intercos and is also configured on the interfaces connected to our ISRs. The switch ports facing the ISRs are all in mode access VLAN100. The routers interfaces add the L3 to this infrastructure.
My question is, how can we use MPLS to backup this carrier ethernet solution without creating a second VLAN/dedicating a second IP subnet and using basic static routing with a matrix to converge the traffic in the event of a failure. This is not what we want. We want to keep the service as a L2 service and have only 1 IP subnet. To further complicate the requirement, we only want to use the backup solution if the primary service goes down, thus eliminating a port-channel/xconnect type configuration.