Method and system for intelligently forwarding multicast packets

• US 7,389,359 B2
• Filed: 10/19/2001
• Issued: 06/17/2008
• Est. Priority Date: 10/19/2001
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Foundry Networks Incorporated (Broadcom, Inc.)
• Inventors: Chen, Lee, Ferguson, Earl, Jain, Nitin, Zhu, Min
• Primary Examiner(s): Dalencourt; Yves
• Application Number:
  US09/982,106
• Publication Number:
  US 20030079040A1
• Time in Patent Office: 2,433 Days
• Field of Search: 709/223, 709/227, 709/238, 709/239, 709/242, 709/249, 713/160, 713/162, 370/471
• US Class Current: 709/238
• CPC Class Codes: H04L 12/1886 with traffic restrictions for efficiency improvement, e.g. involving subnets or subdomains

Abstract

A routing system utilizes a layer 2 switch interconnecting several routers to intelligently forward multicast packets throughout an internet exchange carrying multicast content. The layer 2 switch performs protocol snooping to extract a lookup key that is based on network layer protocol information. The lookup key is uniquely formulated to support either shared or explicit source distribution trees. The lookup key is used to query a forwarding memory that returns an outgoing port index. The outgoing port index points to one or more outgoing ports that are eligible to receive the multicast packet. The outgoing ports are also connected to the neighboring device(s) that are designated to receive the multicast packet. The routing system also supports real time maintenance and updating of the forwarding memory based on the periodic exchange of control messages. The routing system is configured to support PIM routers operating in PIM SM or PIM SSM modes. However, the routing system can also support other multicast protocols and/or standards.

Claims

1. A method for handling a control message in a Virtual Local Area Network (VLAN), the method comprising:

receiving a control message at a layer 2 switch of said VLAN, said control message sent by a layer 3 router;

determining if the control message establishes shared source distribution trees or explicit source distribution trees;

updating a source-group data structure using information from the control message, the source-group data structure containing data regarding a multicast group, if the control message establishes shared source distribution trees;

adding an outgoing port index to said source-group data structure, said outgoing port index identifying a port that received the control message if the control message establishes shared source distribution trees;

deriving an explicit source lookup key from the control message if the control message establishes explicit source distribution trees;

retrieving an outgoing port index associated with an entry in a session data structure, said entry corresponding to said explicit source lookup key if the control message establishes explicit source distribution trees; and

updating an outgoing lookup table entry corresponding to said outgoing port index with information regarding designated devices in said multicast group indicated by the control message if the control message establishes explicit source distribution trees.

2. The method of claim 1, wherein said source-group data structure is a source-group table.

3. The method of claim 1, further comprising:

creating an entry in an outgoing port lookup table, said entry associating said outgoing port index to said port that received the control message if the control message establishes shared source distribution trees.

4. The method of claim 1, further comprising:

searching in a forwarding table for a forwarding entry having a destination hardware address matching a destination hardware address for a multicast group indicated by the control message if the control message establishes shared source distribution trees; and

updating said forwarding entry in said forwarding table if a destination hardware address matching a destination hardware address for said multicast group is found and if the control message establishes shared source distribution trees.

5. The method of claim 1, wherein said session data structure is a session table.

6. The method of claim 1, further comprising:

determining if the control message is a hello or join/prune message; and

performing said determining, updating a source-group data structure, adding, deriving, retrieving, and updating an outgoing lookup table entry only if said control message is a join/prune message.

7. The method of claim 6, further comprising:

creating or updating a neighbor list using said hello message, said neighbor list identifying address and port information regarding a device which sent the control message.

8. The method of claim 1, wherein incoming ports and outgoing ports of said switch form part of said VLAN.

9. The method of claim 1, wherein said control message comprises a layer 3 control message.

10. An apparatus for handling a control message in a Virtual Local Area Network (VLAN), the apparatus comprising:

receiving a control message at a layer 2 switch of said VLAN, said control message sent by a layer 3 router;

means for determining if the control message establishes shared source distribution trees or explicit source distribution trees;

means for updating a source-group data structure using information from the control message, the source-group data structure containing data regarding a multicast group if the control message establishes shared source distribution trees;

means for adding an outgoing port index to said source-group data structure, said outgoing port index identifying a port that received the control message, if the control message establishes shared source distribution trees;

means for deriving an explicit source lookup key from the control message if the control message establishes explicit source distribution trees;

means for retrieving an outgoing port index associated with an entry in a session data structure, said entry corresponding to said explicit source lookup key, if the control message establishes explicit source distribution trees; and

means for updating an outgoing lookup table entry corresponding to said outgoing port index with information regarding designated devices in said multicast group indicated by the control message if the control message establishes explicit source distribution trees.

11. The apparatus of claim 10, wherein said source-group data structure is a source-group table.

12. The apparatus of claim 10, further comprising:

means for creating an entry in an outgoing port lookup table, said entry associating said outgoing port index to said port that received the control message if the control message establishes shared source distribution trees.

13. The apparatus of claim 10, further comprising:

means for searching in a forwarding table for a forwarding entry having a destination hardware address matching a destination hardware address for a multicast group indicated by the control message if the control message establishes shared source distribution trees; and

means for updating said forwarding entry in said forwarding table if a destination hardware address matching a destination hardware address for said multicast group is found and if the control message establishes shared source distribution trees.

14. The apparatus of claim 10 wherein said session data structure is a session table.

15. The apparatus of claim 10, further comprising:

means for determining if the control message is a hello or join/prune message; and

means for performing said determining, updating a source-group data structure, adding, deriving, retrieving, and updating an outgoing lookup table entry only if said control message is a join/prune message.

16. The apparatus of claim 15, further comprising:

creating or updating a neighbor list using said hello message, said neighbor list identifying address and port.

17. The apparatus of claim 10, wherein incoming ports and outgoing ports of said switch form part of said VLAN.

18. The apparatus of claim 10, wherein said control message comprises a layer 3 control message.

19. A program storage device readable by a machine, embodying a program of instructions executable by the machine to perform a method for handling a control message in a Virtual Local Area Network (VLAN), the method comprising:

receiving a control message at a layer 2 switch of said VLAN, said control message sent by a layer 3 router;

determining if the control message establishes shared source distribution trees or explicit source distribution trees;

updating a source-group data structure using information from the control message, the source-group data structure containing data regarding a multicast group if the control message establishes shared source distribution trees;

adding an outgoing port index to said source-group table, said outgoing port index identifying a port that received the control message, if the control message establishes shared source distribution trees;

deriving an explicit source lookup key from the control message if the control message establishes explicit source distribution trees;

retrieving an outgoing port index associated with an entry in a session data structure, said entry corresponding to said explicit source lookup key, if the control message establishes explicit source distribution trees; and

updating an outgoing lookup table entry corresponding to said outgoing port index with information regarding designated devices in said multicast group indicated by the control message if the control message establishes explicit source distribution trees.

20. A method for handling a control message in a Virtual Local Area Network (VLAN), the method comprising:

receiving a control message at a layer 2 switch of said VLAN, said control message sent by a layer 3 router;

deriving a shared source lookup key from multicast group information in the control message;

searching a forwarding data structure for a forwarding entry having a shared source lookup key matching the shared source lookup key;

if a forwarding entry having a shared source lookup key matching the destination shared source lookup key is found, revising an associated outgoing port in the forwarding entry to match an incoming port for the control message;

extracting multicast group information from the control message;

updating a source-group data structure with the multicast group information; and

adding an outgoing port index to the source-group table, the outgoing port index identifying a port that received the control message.

21. The method of claim 20, wherein the shared source lookup key is a destination media access control (MAC) address for the control message.

22. The method of claim 20, wherein the source-group data structure is a source-group table.

23. The method of claim 20, wherein the forwarding data structure is a forwarding table.

24. The method of claim 20, wherein incoming ports and outgoing ports of said switch form part of said VLAN.

25. The method of claim 20, wherein said control message comprises a layer 3 control message.