The 7950 XRS, 7750 SR, and 7450 ESS perform the packet replication required for broadcast and multicast traffic across the bridged domain. MAC address learning is performed by the router to reduce the amount of unknown destination MAC address flooding.
The 7450 ESS, 7750 SR, and 7950 XRS routers learn the source MAC addresses of the traffic arriving on their access and network ports.
Each router maintains an FDB for each VPLS service instance and learned MAC addresses are populated in the FDB table of the service. All traffic is switched based on MAC addresses and forwarded between all objects in the VPLS service. Unknown destination packets (for example, the destination MAC address has not been learned) are forwarded on all objects to all participating nodes for that service until the target station responds and the MAC address is learned by the routers associated with that service.