Multicast echo removal

• US 6,765,907 B1
• Filed: 06/26/2002
• Issued: 07/20/2004
• Est. Priority Date: 03/16/1999
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Xu, Xi, Lou, Shuxian, Zhang, Shujin
• Primary Examiner(s): VANDERPUYE, KENNETH N
• Application Number:
  US10/185,989
• Time in Patent Office: 755 Days
• Field of Search: 370/390, 370/401, 370/432, 370/312
• US Class Current: 370/390
• CPC Class Codes: H04L 12/18 for broadcast or conference , e.g. multicast
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling
• CPC Class Codes: H04L 12/4625 Single bridge functionality, e.g. connection of two networks over a single bridge
• CPC Class Codes: H04L 49/201 Multicast operation; Broadcast operation
• CPC Class Codes: H04L 49/351 for local area network [LAN], e.g. Ethernet switches

Abstract

An apparatus is provided which processes upstream multicast packets and downstream multicast packets in a manner such as to avoid the problem of multicast echo which is generated from a host gateway. For upstream multicast packets, a method is provided which includes: extracting the source network address from the upstream multicast packet; storing said source network address in a table corresponding to the destination host gateway of the packet; and forwarding the upstream multicast packet to the destination network address. For downstream multicast packets, a method is provided which includes: accessing a table corresponding to the host gateway from which the packet was sent; determining if said source network address of the multicast packet is identical to an entry in said table; discarding the multicast packet if said source network address is identical to an entry in said table; and forwarding the multicast packet to said destination network address if said source network address is not identical to an entry in said table. This eliminates any downstream multicast packets which originated from one of the hosts coupled to the apparatus, and thus prevents multicast echo problems from occurring.

Claims

1. A method for processing an upstream multicast packet, the upstream multicast packet having a source network address, a destination network address, and associated with a destination host gateway, the method comprising:

extracting the source network address from the upstream multicast packet;

storing said network address in a table corresponding to the destination host gateway of the upstream multicast packet; and

forwarding the upstream multicast packet to the destination network address.

2. The method of claim 1, wherein said table is a hash table.

12. The program storage device of claim 1, wherein said table is a hash table.

3. A method for processing a downstream multicast packet sent from a host gateway, the downstream multicast packet having a source network address and a destination network address, the method including:

accessing a table corresponding to the host gateway, wherein said table includes a list of network addresses;

determining if said source network address is identical to an entry in said table;

discarding said multicast packet if said source network address is identical to an entry in said table; and

forwarding the multicast packet to said destination network address if said source network address is not identical to an entry in said table.

4. The method of claim 3, wherein said table is a hash table.

5. The method of claim 3, wherein said accessing includes:

taking information regarding the port on which the multicast packet arrived; and

using said information to determine from which host gateway the multicast packet arrived.

6. An apparatus for processing an upstream multicast packet, the upstream multicast packet having a source network address, a destination network address, and associated with a destination host gateway, the apparatus including:

a source network address extractor;

one or more tables, each of said tables corresponding to a different host gateway;

a source network address storer coupled to said source network address extractor and coupled to the one of said one or more tables corresponding to the destination host gateway; and

an upstream multicast packet forwarder coupled to said source network address storer.

7. The apparatus of claim 6, wherein said table is a hash table.

8. An apparatus for processing a downstream multicast packet sent from a host gateway, the downstream multicast packet having a source network address and a destination network address, the apparatus including:

a table corresponding to the host gateway, said table containing a list of network addresses;

a table accessor coupled to said table;

a source network address comparator coupled to said table accessor;

a multicast packet discarder coupled to said source network address comparator if said source network address is identical to an entry in said table; and

a multicast packet forwarder coupled to said source network address comparator if said source network address is not identical to an entry in said table.

9. The apparatus of claim 8, wherein said table is a hash table.

10. The apparatus of claim 8, wherein said table accessor includes:

an information accessor; and

a host gateway determiner couped to said information accessor.

11. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for processing an upstream multicast packet, the upstream multicast packet having a source network address, a destination network address, and associated with a destination host gateway, the method comprising:

extracting the source network address from the upstream multicast packet;

storing said network address in a table corresponding to the destination host gateway of the upstream multicast packet; and

forwarding the upstream multicast packet to the destination network address.

13. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for processing a downstream multicast packet sent from a host gateway, the downstream multicast packet having a source network address and a destination network address, said method including:

accessing a table corresponding to the host gateway, wherein said table includes a list of network addresses;

determining if said source network address is identical to an entry in said table;

discarding said multicast packet if said source network address is identical to an entry in said table; and

forwarding the multicast packet to said destination network address if said source network address is not identical to an entry in said table.

14. The program storage device of claim 13, wherein said table is a hash table.

15. The program storage device of claim 13, wherein said accessing includes:

taking information regarding the port on which the multicast packet arrived; and

using said information to determine from which host gateway the multicast packet arrived.

16. An apparatus for processing an upstream multicast packet, the upstream multicast packet having a source network address, a destination network address, and a destination host gateway, the apparatus comprising:

means for extracting the source network address from the upstream multicast packet;

means for storing said source network address in a table corresponding to the destination host gateway of the upstream multicast packet; and

means for forwarding the upstream multicast packet to the destination network address.

17. The apparatus of claim 16, wherein said table is a hash table.

18. An apparatus for processing a downstream multicast packet sent from a host gateway, the downstream multicast packet having a source network address and a destination network address, the apparatus including:

means for accessing a table corresponding to the host gateway, wherein said table includes a list of network addresses;

means for determining if said source network address is identical to an entry in said table;

means for discarding said multicast packet if said source network address is identical to an entry in said table; and

means for forwarding the multicast packet to said destination network address if said source network address is not identical to an entry in said table.

19. The apparatus of claim 18, wherein said table is a hash table.

20. The apparatus of claim 19, wherein said accessing includes:

means for taking information regarding the port on which the multicast packet arrived; and

means for using said information to determine from which host gateway the multicast packet arrived.