Cisco Technology, Inc.

Ishan Wu

Yiqun Cai

Nagarani Chandika

Ramana Mellacheruva

Toerless Eckert

Sundher Narayanaswamy

Isidoros Kouvelas

Senthil Arunachalam

A method, system, computer program product and apparatus are presented to enable a L2 network device, such as a bridge or switch, to control the flow of a multicast data stream to a connected router in response to control messages received from the router by the L2 network device. By controlling the flow of multicast data streams in this manner, there will be a corresponding reduction in wasted bandwidth due to unnecessary transmission of these multicast data streams and a reduction in processing overhead by the router due to analysis and dropping of unnecessary multicast frames. In one aspect of the present invention, the router can generate the control messages in response to receiving a data frame in a multicast data stream from the L2 network device. The router can determine whether a subscriber to that multicast data stream is connected downstream of the router and then transmit an appropriate control message to the upstream L2 network device, indicating whether the router does or does not have a downstream subscriber. In response to such a control message, the L2 network device can cease transmitting the multicast data stream to the router, if appropriate.

Constraining multicast traffic between a layer 2 network device and a router

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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Cupertino, CA, United States of America

Ishan Wu