HIGH-SPEED PROCESSING OF MULTICAST CONTENT REQUESTS

• US 20100202452A1
• Filed: 02/11/2009
• Published: 08/12/2010
• Est. Priority Date: 02/11/2009
• Status: Active Grant

• Current Assignee: Portsmouth Network Corporation
• Original Assignee: Corrigent Systems Ltd. (Orckit-Corrigent )
• Inventors: RAM, RAFI, SOLOMON, RONEN
• Granted Patent: US 8,014,394 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 49/10 characterised by the switching fabric construction
• CPC Class Codes: H04L 49/111 Switch interfaces, e.g. port details
• CPC Class Codes: H04L 49/557 Error correction, e.g. fault recovery or fault tolerance

Abstract

A method for communication includes operating a network element, which includes multiple ports and multiple interconnected processing units, such that each processing unit is assigned to process packets that are communicated over a respective set of one or more of the ports. Each processing unit stores a respective list, which indicates one or more multicast packet streams that are permitted for forwarding by the network element, and further indicates a respective subset of the ports over which each of the multicast packet streams is permitted for forwarding.

A request relating to reception of a given multicast packet stream is received from a client. The request is distributed among the multiple processing units, and the respective list in each processing unit is updated responsively to the request. Multicast packets associated with the given multicast packet stream are forwarded selectively by the processing units in accordance with the respective updated lists.

Claims

1. A method for communication, comprising:

operating a network element, which includes multiple ports and multiple interconnected processing units, such that each processing unit is assigned to process packets that are communicated over a respective set of one or more of the ports;

storing in each processing unit a respective list, which indicates one or more multicast packet streams that are permitted for forwarding by the network element, and further indicates a respective subset of the ports over which each of the multicast packet streams is permitted for forwarding;

receiving from a client a request relating to reception of a given multicast packet stream;

distributing the request among the multiple processing units, and updating the respective list in each processing unit responsively to the request; and

selectively forwarding multicast packets associated with the given multicast packet stream by the processing units in accordance with the respective updated lists.

2. The method according to claim 1, wherein storing the list, distributing the request and selectively forwarding the multicast packets are performed by dedicated hardware logic.

3. The method according to claim 1, wherein distributing the request comprises duplicating the request to produce first and second copies, forwarding the first copy to a source of the given multicast packet stream, and distributing the second copy among the multiple processing units.

4. The method according to claim 1, wherein distributing the request comprises distributing among the multiple processing units an identity of an ingress port over which the request was received at the network element, and wherein updating the list comprises causing the list to indicate that the given multicast packet stream is permitted for forwarding over the ingress port.

5. The method according to claim 1, wherein updating the list comprises modifying the list to indicate that the given multicast packet stream is permitted for forwarding over a given port only when a number of the multicast packet streams that are permitted for forwarding over the given port, including the given multicast packet stream, does not exceed a maximum value specified for the given port.

6. The method according to claim 1, wherein operating the network element comprises aggregating two or more of the ports to form a high-capacity port.

7. The method according to claim 6, wherein aggregating the ports comprises setting an upper limit on a number of the multicast packet streams that are permitted for forwarding over the high-capacity port, wherein the request indicates that the given multicast packet stream is to be forwarded over the high-capacity port, and wherein updating the list comprises modifying the list to indicate that the given multicast packet stream is permitted for forwarding over the high-capacity port only when the number of the multicast packet streams that are permitted for forwarding over the high-capacity port, including the given multicast packet stream, does not exceed the upper limit.

8. The method according to claim 7, wherein the ports forming the high-capacity port are assigned to at least two of the processing units, and wherein updating the list comprises holding respective local copies of the number of the multicast packet streams that are permitted for forwarding over the high-capacity port, updating the local copies based on the distributed request, and selectively updating the list in each of the at least two processing units based on the respective local copies.

9. The method according to claim 1, wherein updating the list comprises tracking a use of a permission to forward a certain multicast packet stream over a certain port by monitoring requests relating to the certain multicast packet stream that are received at the network element, and removing the permission from the list responsively to determining that the permission is aged.

10. The method according to claim 1, wherein operating the network element comprises initializing a new processing unit added to the network element by:

deactivating the ports to which the new processing unit is assigned;

while the ports to which the new processing unit is assigned are deactivated, sending a multicast status request, receiving multicast membership reports sent by multicast clients in response to the multicast status request, constructing the list by the new processing unit based on the received multicast membership reports; and

after constructing the list, activating the ports to which the new processing unit is assigned.

11. The method according to claim 1, wherein the request specifies a requested action selected from a group of actions consisting of receiving the given multicast packet stream and stopping to receive the given multicast packet stream.

12. The method according to claim 1, wherein the request conforms to one of an Internet Group Management Protocol (IGMP) and a Multicast Listener Discovery (MLD) protocol.

13. A method for communication, comprising:

operating first and second network elements for forwarding multicast packet streams, such that during a given time period the first network element serves as an active network element and the second network element serves as backup to the first network element;

during the given time period, updating in the first and second network elements respective first and second lists of one or more of the multicast packet streams that are permitted for forwarding, and selectively forwarding the multicast packet streams by the first network element in accordance with the first list; and

in response to an event that causes the first network element to become inactive, replacing the first network element with the second network element as the active network element, and selectively forwarding the multicast packet streams by the second network element in accordance with the second list.

14. The method according to claim 13, wherein updating the second list comprises receiving at the second network element a request relating to reception of a given multicast packet stream, and updating the second list responsively to the request.

15. The method according to claim 14, and comprising forwarding the request to a source of the given multicast packet stream, so as to cause the source to forward the given multicast packet stream to the second network element.

16. The method according to claim 15, and comprising discarding the given multicast packet stream by the second network element during the given time period.

17. The method according to claim 14, wherein the request specifies a requested action selected from a group of actions consisting of receiving the given multicast packet stream and stopping to receive the given multicast packet stream.

18. The method according to claim 14, wherein the request conforms to one of an Internet Group Management Protocol (IGMP) and a Multicast Listener Discovery (MLD) protocol.

19. A network element, comprising:

multiple ports; and

multiple interconnected processing units, which are configured to process packets that are communicated over respective sets of one or more of the ports, to store respective lists, which indicate one or more multicast packet streams that are permitted for forwarding by the network element and further indicate a respective subset of the ports over which each of the multicast packet streams is permitted for forwarding, to receive from a client a request relating to reception of a given multicast packet stream, and to distribute the request among the processing units so as to update the lists responsively to the distributed request and to selectively forward multicast packets associated with the given multicast packet stream in accordance with the updated lists.

20. The network element according to claim 19, wherein the processing units comprise dedicated hardware logic for storing the lists, distributing the request and selectively forwarding the multicast packets.

21. The network element according to claim 19, wherein a processing unit receiving the request is configured to duplicate the request to produce first and second copies, so as to forward the first copy to a source of the given multicast packet stream and distribute the second copy among the multiple processing units.

22. The network element according to claim 19, wherein a processing unit receiving the request is configured to distribute among the multiple processing units an identity of an ingress port over which the request was received, and wherein the processing units are configured to cause the respective lists to indicate that the given multicast packet stream is permitted for forwarding over the ingress port.

23. The network element according to claim 19, wherein the processing units are configured to update the list to indicate that the given multicast packet stream is permitted for forwarding over a given port only when a number of the multicast packet streams that are permitted for forwarding over the given port, including the given multicast packet stream, does not exceed a maximum value specified for the given port.

24. The network element according to claim 19, wherein two or more of the ports are aggregated to form a high-capacity port.

25. The network element according to claim 24, wherein an upper limit is set on a number of the multicast packet streams that are permitted for forwarding over the high-capacity port, wherein the request indicates that the given multicast packet stream is to be forwarded over the high-capacity port, and wherein the processing units are configured to update the lists to indicate that the given multicast packet stream is permitted for forwarding over the high-capacity port only when the number of the multicast packet streams that are permitted for forwarding over the high-capacity port, including the given multicast packet stream, does not exceed the upper limit.

26. The network element according to claim 25, wherein the ports forming the high-capacity port are assigned to at least two of the processing units, and wherein the at least two processing units are configured to hold respective local copies of the number of the multicast packet streams that are permitted for forwarding over the high-capacity port, to update the local copies based on the distributed request, and to selectively update their respective lists based on the respective local copies.

27. The network element according to claim 19, wherein the processing units are configured to track a use of a permission to forward a certain multicast packet stream over a certain port by monitoring requests relating to the certain multicast packet stream that are received at the network element, and to remove the permission from the respective lists responsively to determining that the permission is aged.

28. The network element according to claim 19, wherein a new processing unit added to the network element is configured to initialize by:

deactivating the ports to which the new processing unit is assigned;

while the ports to which the new processing unit is assigned are deactivated, sending a multicast status request, receiving multicast membership reports sent by multicast clients in response to the multicast status request, constructing the list by the new processing unit based on the received multicast membership reports; and

after constructing the list, activating the ports to which the new processing unit is assigned.

29. The network element according to claim 19, wherein the request specifies a requested action selected from a group of actions consisting of receiving the given multicast packet stream and stopping to receive the given multicast packet stream.

30. The network element according to claim 19, wherein the request conforms to one of an Internet Group Management Protocol (IGMP) and a Multicast Listener Discovery (MLD) protocol.

31. A network element, comprising:

one or more ports; and

one or more processing units, which are coupled to the ports and are configured to update, during a time period in which the network element serves as backup to another network element serving as an active network element, a list of one or more multicast packet streams that are permitted for forwarding, and, in response to an event that causes the other network element to become inactive, to replace the other network element as the active network element, and to selectively forward the multicast packet streams in accordance with the updated list.

32. The network element according to claim 31, wherein the processing units are configured to receive during the time period a request relating to reception of a given multicast packet stream, and to update the list responsively to the request.

33. The network element according to claim 32, wherein the processing units are configured to forward the request to a source of the given multicast packet stream, so as to cause the source to forward the given multicast packet stream to the network element.

34. The network element according to claim 33, wherein the processing units are configured to discard the given multicast packet stream during the given time period.

35. The network element according to claim 32, wherein the request specifies a requested action selected from a group of actions consisting of receiving the given multicast packet stream and stopping to receive the given multicast packet stream.

36. The network element according to claim 32, wherein the request conforms to one of an Internet Group Management Protocol (IGMP) and a Multicast Listener Discovery (MLD) protocol.

37. A communication system, comprising first and second network elements, which are configured to update, during a given time period in which the first network element serves as an active network element and the second network element serves as backup to the first network element, respective first and second lists of one or more multicast packet streams that are permitted for forwarding, to selectively forward the multicast packet streams during the given time period by the first network element in accordance with the first list, and, in response to an event that causes the first network element to become inactive, to replace the first network element with the second network element as the active network element and to selectively forward the multicast packet streams by the second network element in accordance with the second list.