Reverse path forwarding lookup with link bundles

• US 20130034097A1
• Filed: 08/03/2011
• Published: 02/07/2013
• Est. Priority Date: 08/03/2011
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Maddury, Mahesh, Matus, Francisco, Dharmapurikar, Sarang
• Granted Patent: US 8,873,558 B2
• Time in Patent Office: Days
• US Class Current: 370/390
• CPC Class Codes: H04L 45/026 Details of "hello" or keep-alive messages
• CPC Class Codes: H04L 45/16 Multipoint routing
• CPC Class Codes: H04L 45/245 Link aggregation, e.g. trunking
• CPC Class Codes: H04L 45/54 Organization of routing tables
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

In one embodiment, a method includes receiving a packet at an interface at a network device having a plurality of interfaces connected to a plurality of links forming a bundle, performing a Reverse Path Forwarding (RPF) check on the received packet, and forwarding the packet if it passes the RPF check. The RPF check includes a lookup in an RPF table having a plurality of entries for the bundle, each of the entries including the bundle and one of the links in the bundle, and verification that the interface receiving the packet is connected to one of the links in the bundle identified in the lookup. An apparatus is also disclosed.

Claims

1. A method comprising:

receiving a packet at an interface at a network device comprising a plurality of interfaces connected to a plurality of links forming a bundle;

performing a Reverse Path Forwarding (RPF) check on the received packet; and

forwarding the packet if the packet passes said RPF check;

wherein said RPF check comprises;

a lookup in an RPF table comprising a plurality of entries for said bundle, each of said entries comprising said bundle and one of the links in said bundle; and

verification that the interface receiving the packet is connected to one of the links in said bundle identified in said lookup.

2. The method of claim 1 wherein said bundle comprises an equal cost multi-path bundle and the lookup is based on a source address in the packet.

3. The method of claim 1 wherein performing said RPF check comprises performing a security binding check for unicast.

4. The method of claim 1 wherein said plurality of links are connected to Protocol Independent Multicast (PIM) routers and said lookup is based on a multicast group address in the packet.

5. The method of claim 4 wherein the network device is configured for bidirectional-PIM operation and said plurality of links are in communication with designated forwarders.

6. The method of claim 1 wherein the RPF table comprises a hash table.

7. The method of claim 1 wherein the RPF table comprises a plurality of entries for at least one other bundle.

8. The method of claim 1 wherein said bundle comprises more than eight links.

9. The method of claim 1 wherein said bundle comprises more than one hundred links.

10. An apparatus comprising:

a plurality of interfaces for connection to a plurality of links forming a bundle;

a processor for receiving a packet, performing a Reverse Path Forwarding (RPF) check on the received packet, and forwarding the packet if the packet passes said RPF check; and

memory for storing an RPF table comprising a plurality of entries for said bundle, each of said entries comprising said bundle and one of the links in said bundle;

wherein said RPF check comprises a lookup in the RPF table and verification that the interface receiving the packet is connected to one of the links in said bundle identified in said lookup.

11. The apparatus of claim 10 wherein said bundle comprises an equal cost multi-path bundle and said lookup is based on a source address contained in the packet.

12. The apparatus of claim 10 wherein performing said RPF check comprises performing a security binding check for unicast.

13. The apparatus of claim 10 wherein said plurality of links are connected to Protocol Independent Multicast (PIM) routers and said lookup is based on a multicast group address in the packet.

14. The apparatus of claim 13 wherein the processor is configured for bidirectional-PIM operation and said plurality of links are in communication with designated forwarders.

15. The apparatus of claim 10 wherein the RPF table comprises a hash table.

16. An apparatus comprising:

means for performing a Reverse Path Forwarding (RPF) check on a packet received at an interface, the apparatus comprising a plurality of interfaces for connection to a plurality of links forming a bundle; and

means for forwarding the packet if the packet passes said RPF check;

wherein said RPF check comprises;

a lookup in an RPF table comprising a plurality of entries for said bundle, each of said entries comprising said bundle and one of the links in said bundle; and

verification that the interface receiving the packet is connected to one of the links in said bundle identified in said lookup.

17. The apparatus of claim 16 wherein said bundle comprises an equal cost multi-path bundle and said lookup is based on a source address in the packet.

18. The apparatus of claim 16 wherein performing said RPF check comprises performing a security binding check for unicast.

19. The apparatus of claim 16 wherein said plurality of links are connected to Protocol Independent Multicast (PIM) routers and said lookup is based on a multicast group address in the packet.

20. The apparatus of claim 16 wherein the apparatus is configured to perform the lookup in hardware.