Network bridge with multicast forwarding table
First Claim
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1. In a hierarchical communications network comprising:
- a plurality of interconnected routers anda plurality of subnetworks connected to said routers, wherein each of said subnetworks comprises;
one or more network segments, andone or more bridges interconnecting said network segments andconnecting each said subnetwork to one or more of said routers, andwherein each network segment comprises one or more hosts, a process for providing multicast communication comprising the steps of;
transmitting from a selected one of said hosts on a route to a destination one of said routers a multicast control packet indicating a multicast group to which said host belongs,receiving said multicast control packet at a bridge on said route to said destination router,using said multicast control packet, updating a multicast forwarding table entry in a multicast forwarding table corresponding to said multicast group at said bridge,retransmitting said multicast control packet from said bridge on said route to said destination router,using said multicast control packet, updating a routing table at said destination router, andat said bridge, retransmitting multicast message packets destined to said indicated multicast group according to said updated multicast forwarding table maintained at said bridge.
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Abstract
A system and method are disclosed for routing multicast packets in a subnetwork so as to conserve bandwidth in at least some of the network segments or collision domains of the subnetwork. In particular, multicast packets are only retransmitted in the network segments that are on a path to a host that is a member of the multicast group of hosts to which the multicast packet is destined.
247 Citations
13 Claims
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1. In a hierarchical communications network comprising:
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a plurality of interconnected routers and a plurality of subnetworks connected to said routers, wherein each of said subnetworks comprises; one or more network segments, and one or more bridges interconnecting said network segments and connecting each said subnetwork to one or more of said routers, and wherein each network segment comprises one or more hosts, a process for providing multicast communication comprising the steps of; transmitting from a selected one of said hosts on a route to a destination one of said routers a multicast control packet indicating a multicast group to which said host belongs, receiving said multicast control packet at a bridge on said route to said destination router, using said multicast control packet, updating a multicast forwarding table entry in a multicast forwarding table corresponding to said multicast group at said bridge, retransmitting said multicast control packet from said bridge on said route to said destination router, using said multicast control packet, updating a routing table at said destination router, and at said bridge, retransmitting multicast message packets destined to said indicated multicast group according to said updated multicast forwarding table maintained at said bridge. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A bridge in a hierarchical communications network comprising:
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a plurality of I/O interfaces for transmitting packets to, and for receiving packets from, routers and network segments attached to said bridge, said plurality of I/O interfaces including one I/O interface connected to each of said routers and one I/O interface connected to each of said network segments, and a processor connected to said I/O interfaces, for receiving a multicast control packet transmitted from a host of one of said network segments to one destination router of said routers via a route including said bridge, for updating a multicast forwarding table entry in a multicast forwarding table in said bridge corresponding to a multicast group of said multicast control packet, for causing said I/O interface connected to said destination router of said multicast control packet to retransmit said multicast control packet, and for causing said I/O interfaces to retransmit multicast message packets destined to said multicast group according to said multicast forwarding table. - View Dependent Claims (9)
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10. A network bridge, comprising:
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at least two I/O interfaces to each receive and transmit data packets; and a processor operatively coupled to the at least two I/O interfaces; wherein the processor comprises; means for receiving any data packet received by any of the at least two I/O interfaces; means for identifying the received data packet as a multicast control packet destined for a device other than the network bridge; means for identifying the I/O interface on which the identified multicast control packet arrived; means for identifying a multicast group from the multicast control packet; and means for updating a multicast forwarding table entry associated with the determined multicast group. - View Dependent Claims (11, 12, 13)
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Specification