1. We have 3 switches installed in different geological locations and are interconnected via SDH network. applications used on these switches fall under the same subnet and very well communicating via SDH Network since everything is L2.
2. All 3 switches have one more link connecting to its own leased line routers which further terminates into a L3 MPLS cloud.
3. we want to use this link as redundant. if SDH network goes down all the applications will communicate via this L3 MPLS cloud over VPLS configured on the Leased Line Router.
4. we used EIGRP and MPLS and then configured VPLS. all the applications communicate with each other over these links.
5. the issue is only one link works at a time, meaning all Applications communicate fine via SDH Network only when the interfaces connected to the Leased Line Router are shutdown and Vice Versa.
6. When both the links are a up a broadcast storm is observed and the whole network goes down.
here you go Balaji.. VPLS is configured between LLR1 , 2 & 3. for Switch 1 2 & 3 primary path for communication is via SDH and redundant path is via LLRs over VPLS. Node 7 is MPLS cloud i dont why but for some reason i wasn't able to change the name.