Cisco Technology, Inc.

Ramana Mellacheruva

Yiqun Cai

Nagarani Chandika

Ishan Wu

A method and apparatus for a downstream router to inform an upstream router by use of packets of a new router command protocol that the upstream router is to forward multicast packets of a specified group to the downstream router. First the downstream router transmits a HELLO packet to upstream router to inform the upstream router that the downstream router is a multicast router implementing the invention. Then, in the event that the downstream router receives a packet from an end station requesting multicast packets of a particular group, in response the downstream router sends a JOIN packet to the upstream router. The JOIN packet requests that the upstream router forward the requested group multicast packets to the downstream router. When a multicast group packet arrives at the upstream router, the upstream router forwards the packet to those downstream routers requesting that group.

Multicast system for forwarding desired multicast packets in a computer network

A method and apparatus for a router to inform a Layerswitch by use of packets of a new router group port management protocol (RGMP) that the layerswitch is to forward multicast packets of a specified group to the router. First the router transmits a RGMP HELLO packet to the layerswitch to inform the switch that the router is a multicast router implementing the invention. Then, in the event that the router receives an IGMP packet from an end station requesting multicast packets of a particular group, in response the router sends an RGMP JOIN packet to the layerswitch. The RGMP JOIN packet requests that the layerswitch forward only multicast group packets, of the group whose group number is written into a field of the RGMP JOIN packet, to the router. Also, the router sends a prior art PIM JOIN packet to other multicast routers in order to be placed on the multicast distribution tree for that group. The layerswitch builds a forwarding table for multicast groups listing ports connected to routers having sent a RGMP JOIN for that group. When a multicast group packet arrives at the layerswitch, the switch uses the forwarding table to forward the packet only to those routers requesting that group.

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Ramana Mellacheruva