Method and apparatus for authorizing multicast forwarding states

• US 20060045085A1
• Filed: 08/24/2004
• Published: 03/02/2006
• Est. Priority Date: 08/24/2004
• Status: Active Grant

• Current Assignee: Avaya Incorporated
• Original Assignee: Avaya Incorporated
• Inventors: He, Haixiang
• Granted Patent: US 9,065,669 B2
• Time in Patent Office: Days
• US Class Current: 370/390
• CPC Class Codes: H04L 12/18 for broadcast or conference , e.g. multicast
• CPC Class Codes: H04L 12/185 with management of multicast group membership
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: H04L 63/08 for authentication of entities cryptographic mechanisms or cryptographic arrangements for entity authentication H04L9/32

Abstract

A method and apparatus for authorizing forwarding states in a Layer 2 device of a multicast system includes a forwarding table for use in forwarding communications to group members over interfaces of the Layer 2 device. According to one aspect of the invention, associated with the forwarding state is an authorization flag. The authorization flag signals whether or not the forwarding state is an authorized forwarding state over which multicast communications may be transferred. The Layer 2 device snoops authorization communications between a host and a layer 3 device, and updates the forwarding table authorization flags in response to these communications.

Claims

1. An apparatus for authorizing multicast forwarding states includes:

a switch having a plurality of input interfaces and a plurality of output interfaces, the switch including a forwarding table including an entry for each one of the output interface, the entry including a group and a flag, the group indicating a multicast group of which the apparatus desires to be a member and the flag indicating whether the apparatus is authorized to receive content for that group.

2. The apparatus of claim 1 comprising means for snooping communications between a host device and a layer 3 device coupled to the switch, the means for snooping including means for identifying group membership communications between the host device and the layer 3 device.

3. The apparatus of claim 2 wherein the group communications use an Internet Group Management with Authentication (IGAP) protocol.

4. The apparatus of claim 2 including means for generating the entry in the forwarding table in response to the communications, including means for setting the flag associated with the entry in response to the communications.

5. The apparatus of claim 2 including means for deleting the entry in the forwarding table in response to the communications between the host device and the layer 3 device.

6. A method for authorizing multicast forwarding states at a device includes the steps of:

snooping communications between a router and a host, the communications including communications associated with group membership of the host;

detecting, at the device, a communication associated with group membership of the host, the communication identifying a group in which the host desires to be a member;

storing a forwarding state associated with the group in a forwarding table, the step of storing including setting a flag corresponding to the forwarding state to indicate that the forwarding state is unauthorized;

forwarding multicast communications to the host for the group in response to the flag.

7. The method as recited in claim 6, including the step of

monitoring communications between the router and the host to detect authorization of the forwarding state, including setting the flag corresponding to the forwarding state to indicate that the forwarding state is authorized in response to detection of a communication between the router and the host indicating such authorization.

8. The method of claim 6 including the step of deleting the forwarding state associated with the group in response to a group termination message exchanged between the router and the host.

9. The method of claim 8 wherein communications between the router and the host use an Internet Group Management and Authorization Protocol (IGAP).

10. The method of claim 9 wherein the communication is an IGAP Join.

11. The method of claim 9 wherein the group termination message is an IGAP Leave message issued by the host.

12. The method of claim 9 wherein the group termination message is an Accounting Stop Notification issued by the router.

13. A multicast system comprising:

a host device;

a layer 2 device, coupled to the host device; and

a layer 3 device, coupled to the layer 2 device, the layer 3 device including authorization logic, for authorizing membership in a multicast group, wherein the host and the layer 3 device exchange communications regarding host group membership, the communications including authorization communications, and wherein the layer 2 device includes a table for storing forwarding states for groups associated with the host, the forwarding state including an authorization flag indicating whether the host is authorized to receive communications for the group, the authorization flag set in response to snooped authorization communications.