PIM Designated Router Load Balancing

On a multi-access network, one of the PIM routers is elected as a Designated Router (DR). On the last hop LAN, the PIM DR is responsible for tracking local multicast listeners and forwarding traffic to these listeners if the group is operating in PIM-SM. This document specifies a modification to the PIM-SM protocol that allows more than one of these last hop routers to be selected, so that the forwarding load can be distributed among these routers.