Network bridge with multicast forwarding table
AssigneeCabletron Systems, Inc.
InventorKenneth Virgile
Life of this patent
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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.
Claims25
A method of providing multicast communications in a network bridge having a multicast forwarding table and including at least two I/O interfaces to each receive and transmit data packets, the method comprising steps of:
- (a) retrieving a data packet received on any of the at least two I/O interfaces;
- (b) identifying the I/O interface on which the retrieved data packet arrived;
- (c) determining whether the retrieved data packet is a multicast control packet destined for a device other than the network bridge;
- (d) when the retrieved data packet is determined to be a multicast control packet destined for a device other than the network bridge;
- (e) identifying a multicast group from the multicast control packet;
- (e1) determining a source of the multicast control packet;
- and
- (f) updating the multicast forwarding table, said updating comprising updating an entry for the identified multicast group to include the identified I/O interface and the determined source of the multicast control packet;
- and when no entry exists in the multicast forwarding table for the identified multicast group, adding a new entry for the identified multicast group to the multicast forwarding table, wherein the new entry cross-references the identified multicast group to the identified I/O interface and to the determined source of the multicast control packet.
A method of providing multicast communications in a network bridge having a multicast forwarding table and including at least two I/O interfaces to each receive and transmit data packets, the method comprising:
- retrieving a data packet received on any of the at least two I/O interfaces;
- identifying the I/O interface on which the retrieved data packet arrived;
- determining whether the retrieved data packet is a multicast control packet destined for a device other than the network bridge;
- when the retrieved data packet is determined to be a multicast control packet destined for a device other than the network bridge:
- identifying a multicast group from the multicast control packet;
- identifying a source of the multicast control packet and
- updating the multicast forwarding table, said updating comprising updating the multicast forwarding table to cross-reference the determined source of the multicast control packet, the identified I/O interface and the identified multicast group;
- determining whether the retrieved data packet is a multicast message packet;
- when the retrieved data packet is determined to be a multicast message packet:
- identifying a multicast destination group from the multicast message packet;
- retrieving an entry from the multicast forwarding table according to the identified multicast destination group, the retrieved entry including at least one cross-referenced I/O interface;
- and
- sending the multicast message packet out each at least one cross-referenced I/O interface in the retrieved multicast forwarding table entry other than the identified I/O interface.
A method of providing multicast communications in a network bridge having a multicast forwarding table including at least two I/O interfaces to each receive and transmit data packets, the method comprising:
- retrieving a data packet received on any of the at least two I/O interfaces;
- identifying the I/O interface on which the retrieved data packet arrived;
- determining whether the retrieved data packet is a multicast control packet destined for a device other than the network bridge;
- when the retrieved data packet is determined to be a multicast control packet destined for a device other than the network bridge:
- identifying a multicast group from the multicast control packet;
- and
- updating the multicast forwarding table, said updating comprising updating an entry in the multicast forwarding table to cross-reference the identified I/O interface and the identified multicast group;
- determining whether the retrieved data packet is a multicast message packet;
- when the retrieved data packet is determined to be a multicast message packet:
- identifying a multicast destination group from the multicast message packet;
- retrieving an entry from the multicast forwarding table according to the identified multicast destination group, the retrieved entry including at least one cross-referenced I/O interface;
- and
- sending the multicast message packet out each at least one cross-referenced I/O interface in the retrieved multicast forwarding table entry other than the identified I/O interface on which the multicast message packet arrived.
Dependencies are inferred from the claim text.