System and method for IP multicast
View Patent ↗A system and method for routing multicast packets. A multicast packet is received at an inbound interface on a switch/router. S,G data are obtained from the packet and used to search an OIL table. If the S,G data are found in the OIL table, the packet is forwarded on an outbound interface associated with the S,G data. If the S,G data are not found in the OIL table, the multicast routing table is consulted to obtain a longest match for the packet, and the packet is forwarded on the interface(s) which correspond to the longest match route. The multicast routing table may include a single entry, such that all packets that do not match an entry in the OIL are forwarded on the same outbound interface. The multicast routing table may include multiple entries with different covered ranges of (S,G).
1. A method for routing multicast packets, the method comprising:
receiving at an inbound interface on a switch/router a multicast packet, wherein the multicast packet comprises source (S) and group (G) addresses;
determining whether the S and G addresses are mapped to an outbound interface in an Outgoing Interface List (OIL) table;
obtaining from the OIL table a single routing entry for an outbound interface, wherein the single routing entry comprises a longest partial match of an address of the outbound interface and the S and G addresses, when the S and G addresses are not mapped to any outbound interface in the OIL table; and
forwarding the multicast packet over the outbound interface.
2. The method of claim 1 , further comprising:
building a second OIL table comprising the routing entry for the outbound interface and the S and G addresses.
3. The method of claim 2 , further comprising detecting Internet Group Management Protocol (IGMP) information for the outbound interface and building the second OIL table comprising the routing entry for the outbound interface and the S and G addresses based on the IGMP information.
4. The method of claim 1 , further comprising:
determining that the S and G addresses fall within a predetermined range of S and G addresses; and
forwarding the multicast packet to a plurality of outbound interfaces in the OIL table regardless of whether the S and G addresses are mapped to an outbound interface of the OIL table.
5. A method for routing multicast packets, the method comprising:
receiving at an inbound interface on a switch/router a multicast packet, wherein the multicast packet comprises source (S) and group (G) addresses;
determining whether the S and G addresses are mapped to an outbound interface in an Outgoing Interface List (OIL) table;
obtaining from the OIL table a first routing entry for a first outbound interface and a second routing entry for a second outbound interface, wherein the first routing entry comprises a partial match of a first address of the first outbound interface and the S and G addresses and the second routing entry comprises a partial match of a second address of the second outbound interface and the S and G addresses, when the S and G addresses are not mapped to an outbound interface in the OIL table;
determining which of the first and second routing entries comprises a longest partial match of the respective first and second outbound interface addresses and the S and G addresses; and
forwarding the multicast packet over the determined first or second outbound interface.
6. The method of claim 5 , wherein the first and second routing entries further comprise disjointed partial matches of the respective first and second outbound interface addresses and the S and G addresses.
7. The method of claim 5 , wherein the first and second routing entries further comprise overlapping partial matches of the respective first and second outbound interface addresses and the S and G addresses.
8. The method of claim 5 , further comprising:
determining which of the first and second outbound interfaces comprises a smaller traffic distribution; and
forwarding the multicast packet over the first or second outbound interface comprising the longest partial match of the respective first and second outbound interface addresses and the S and G addresses and the smaller traffic distribution.
9. A method for routing multicast packets, the method comprising:
receiving at an inbound interface on a switch/router a multicast packet, wherein the multicast packet comprises source (S) and group (G) addresses;
determining whether the S and G addresses are mapped to an outbound interface in an Outgoing Interface List (OIL) table;
obtaining from the OIL table a plurality of routing entries for outbound interfaces, wherein each routing entry comprises a partial match of an address of an outbound interface and the S and G addresses, when the S and G addresses are not mapped to any outbound interface in the OIL table; and
forwarding the multicast packet over each outbound interface.
10. The method of claim 9 , further comprising:
determining a traffic distribution among the each of the outbound interfaces; and
forwarding the multicast packet over the each of the outbound interfaces according to the traffic distribution.