Method and apparatus for authorizing multicast forwarding states

摘要

A method and apparatus for authorizing forwarding states in a Layer 2 device of a multicast system includes a forwarding table for use in forwarding communications to group members over interfaces of the Layer 2 device. According to one aspect of the invention, associated with the forwarding state is an authorization flag. The authorization flag signals whether or not the forwarding state is an authorized forwarding state over which multicast communications may be transferred. The Layer 2 device snoops authorization communications between a host and a layer 3 device, and updates the forwarding table authorization flags in response to these communications.

主权项

1. An apparatus comprising:
a Layer 3 device; a plurality of host devices; and a Layer 2 switch which processes packets sent from the Layer 3 device to the host devices, the Layer 2 switch functioning to:
examine Layer 3 information in the packets to identify changes in multicast group membership of the hosts;update a data record indicative of multicast group membership by:
adding a first host to a first multicast group in response to a report or join message indicative of membership of the first host in the first multicast group; anddeleting the first host from the first multicast group if a corresponding success notification is not received within a predetermined time following the report or join message, or in response to a corresponding leave or accounting stop notification message, prevent a first multicast group packet addressed to the first host device from being forwarded to the first host device if the data record indicates that the first host device is not a member of the first multicast group; andforward the first multicast group packet addressed to the first host device to the first host device if the data record indicates that the first host device is a member of the first multicast group.