Fast path forwarding of link state advertisements using multicast addressing
First Claim
1. A method for propagating link state advertisement protocol messages by a network device in a communication network, the network device having a plurality of interfaces, a fast path for forwarding protocol messages, and a control plane for processing protocol messages, the method comprising:
- determining a multicast distribution tree for forwarding link state advertisement protocol messages from an originating device S to a multicast group G;
receiving a link state advertisement protocol message for the (S,G) pair over an inbound interface; and
forwarding the link state advertisement protocol message by the fast path according to the multicast distribution tree associated with the (S,G) pair independently of any control plane processing of the link state advertisement protocol message.
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Abstract
A link state advertisement protocol message received from an originating device over an inbound interface is forwarded over the fast path according to a multicast distribution tree using a special multicast address. Specifically, a special multicast address is used for the link state advertisement protocol message. The special multicast address differentiates the link state advertisement protocol message from other protocol messages. A multicast routing protocol is used to establish a multicast distribution tree for distributing link state advertisement protocol messages based upon the special multicast address. The multicast distribution tree determines, among other things, the preferred inbound interface for the link state advertisement protocol message and any outbound interfaces to which the link state advertisement protocol message is to be forwarded. The link state advertisement protocol message is forwarded according to the multicast distribution tree. If the link state advertisement protocol message is received over the preferred inbound interface, then the link state advertisement protocol message is forwarded over the fast path to the outbound interface(s) as indicated by the multicast distribution tree. Otherwise, the link state advertisement protocol message is not forwarded over the fast path. The link state advertisement protocol message continues to be processed and forwarded by the control plane as usual for robustness.
46 Citations
28 Claims
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1. A method for propagating link state advertisement protocol messages by a network device in a communication network, the network device having a plurality of interfaces, a fast path for forwarding protocol messages, and a control plane for processing protocol messages, the method comprising:
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determining a multicast distribution tree for forwarding link state advertisement protocol messages from an originating device S to a multicast group G;
receiving a link state advertisement protocol message for the (S,G) pair over an inbound interface; and
forwarding the link state advertisement protocol message by the fast path according to the multicast distribution tree associated with the (S,G) pair independently of any control plane processing of the link state advertisement protocol message. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
running a multicast routing protocol to determine the multicast distribution tree.
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3. The method of claim 2, wherein the multicast distribution tree identifies a preferred inbound interface for the (S,G) pair.
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4. The method of claim 2, wherein the multicast distribution tree identifies outbound interface(s) for the (S,G) pair.
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5. The method of claim 2, further comprising:
installing a multicast forwarding state for the (S,G) pair in a forwarding table, the multicast forwarding state indicating rules for forwarding link state advertisement protocol messages associated with the (S,G) pair.
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6. The method of claim 5, wherein the multicast forwarding state indicates a preferred inbound interface for the (S,G) pair.
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7. The method of claim 5, wherein the multicast forwarding state indicates outbound interface(s) for the (S,G) pair.
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8. The method of claim 1, wherein the multicast distribution tree identifies a preferred inbound interface for the (S,G) pair, and wherein forwarding the link state advertisement protocol message by the fast path according to the multicast distribution tree associated with the (S,G) pair comprises:
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determining whether the inbound interface is the preferred inbound interface for the (S,G) pair; and
forwarding the link state advertisement protocol message by the fast path, if and only if the inbound interface is the preferred inbound interface for the (S,G) pair.
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9. The method of claim 8, wherein determining whether the inbound interface is the preferred inbound interface for the (S,G) pair comprises:
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finding a multicast forwarding state in a forwarding table, the multicast forwarding state indicating the preferred inbound interface for the (S,G) pair; and
determining whether the inbound interface is the preferred inbound interface indicated by the multicast forwarding state.
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10. The method of claim 1, further comprising:
routing the link state advertisement protocol message to the control plane for local processing of the link state advertisement protocol message.
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11. The method of claim 10, further comprising:
forwarding the link state advertisement protocol message by the control plane via the fast path.
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12. A device for propagating a link state advertisement protocol message in a communication network, the device comprising:
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a plurality of interfaces;
a control plane for processing protocol messages; and
a fast path coupled to the control plane and to the plurality of interfaces, the fast path comprising;
receiving logic operably coupled to receive a link state advertisement protocol message from an originating device S to a multicast group G; and
fast path forwarding logic responsive to the receiving logic and operably coupled to forward the link state advertisement protocol message according to a multicast distribution tree for the (S,G) pair independently of any control plane processing of the link state advertisement protocol message. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
multicast routing protocol logic operably coupled to determine the multicast distribution tree for the (S,G) pair.
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14. The device of claim 13, further comprising:
forwarding state installation logic responsive to the multicast routing protocol logic and operably coupled to install a multicast forwarding state in a forwarding table indicating rules for forwarding the link state advertisement protocol messages associated with the (S,G) pair.
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15. The device of claim 14, wherein the multicast forwarding state indicates a preferred inbound interface for the (S,G) pair.
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16. The device of claim 14, wherein the multicast forwarding state indicates outbound interface(s) for the (S,G) pair.
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17. The device of claim 12, further comprising a forwarding table having at least one multicast forwarding state indicating a preferred inbound interface and outbound interface(s) for the (S,G) pair identified by the multicast distribution tree.
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18. The device of claim 17, wherein the fast path forwarding logic is operably coupled to forward the link state advertisement protocol message to all outbound interfaces indicated by the multicast forwarding state, if and only if the inbound interface is the preferred inbound interface indicated by the multicast forwarding state.
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19. The device of claim 12, wherein the fast path forwarding logic is operably coupled to route the link state advertisement protocol message to the control plane for local processing of the link state advertisement protocol message.
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20. The device of claim 19, wherein the control plane is operably coupled to forward the link state advertisement protocol message via the fast path.
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21. A program product comprising a computer readable medium having embodied therein a computer program for propagating a link state advertisement protocol message by a network device in a communication network, the network device having a plurality of interfaces, a fast path for forwarding protocol messages, and a control path for processing control messages, the computer program comprising:
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receiving logic programmed to receive a link state advertisement protocol message from an originating device S to a multicast group G; and
fast path forwarding logic responsive to the receiving logic and programmed to forward the link state advertisement protocol message according to a multicast distribution tree for the (S,G) pair. - View Dependent Claims (22, 23, 24, 25, 26, 27)
multicast routing protocol logicprogrammed to determine the multicast distribution tree for the (S,G) pair.
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23. The program product of claim 22, wherein the computer program further comprises:
forwarding state installation logic responsive to the multicast routing protocol logic and programmed to install a multicast forwarding state in a forwarding table indicating rules for forwarding the link state advertisement protocol messages associated with the (S,G) pair.
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24. The program product of claim 23, wherein the multicast forwarding state indicates a preferred inbound interface for the (S,G) pair.
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25. The program product of claim 23, wherein the multicast forwarding state indicates outbound interface(s) for the (S,G) pair.
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26. The program product of claim 21, wherein the network device includes a forwarding table having at least one multicast forwarding state indicating a preferred inbound interface and outbound interface(s) for the (S,G) pair identified by the multicast distribution tree, and wherein the fast path forwarding logic is programmed to forward the link state advertisement protocol message to all outbound interfaces indicated by the multicast forwarding state, if and only if the inbound interface is the preferred inbound interface indicated by the multicast forwarding state.
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27. The program product of claim 21, wherein the fast path forwarding logic is programmed to route the link state advertisement protocol message to the control plane for local processing of the link state advertisement protocol message.
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28. In a communication system having a plurality of interconnected network devices, each network device having a plurality of interfaces, a fast path for forwarding protocol messages, and a control plane for processing protocol message, a method for propagating link state advertisement protocol messages, the method comprising:
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sending a link state advertisement protocol message by an originating device S to at least one network device using a multicast group address G; and
forwarding the link state advertisement protocol message by the network device over the fast path according to a multicast distribution tree associated with the (S,G) pair independently of any control plane processing of the link state advertisement protocol message.
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Specification