Network fault recovery method and apparatus

• US 6,530,032 B1
• Filed: 09/23/1999
• Issued: 03/04/2003
• Est. Priority Date: 09/23/1999
• Status: Expired due to Term

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Hayward, Kenneth G., Shew, Stephen D.
• Primary Examiner(s): BADERMAN, SCOTT T
• Application Number:
  US09/401,919
• Time in Patent Office: 1,258 Days
• Field of Search: 714/4 709/239-242 370/216,217,218-221,222-228
• US Class Current: 714/4.3
• CPC Class Codes: H04L 41/0663 Performing the actions predefined by failover planning, e.g. switching to standby network elements
• CPC Class Codes: H04L 43/0811 by checking connectivity
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]
• CPC Class Codes: H04L 49/251 Cut-through or wormhole routing
• CPC Class Codes: H04L 49/557 Error correction, e.g. fault recovery or fault tolerance
• CPC Class Codes: H04L 49/602 Multilayer or multiprotocol switching, e.g. IP switching
• CPC Class Codes: H04L 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06

Abstract

The present invention provides layer one, two and three (L1/L2/L3) Integration and L1 cut-through path utilization in an apparatus and method of fault recovery. A switch combines an IP router with L2 capabilities, and an L1 cross connect (optical or electrical). A network of such switches is configured with label switched paths (LSP) that correspond to layer 1 (L1) cut-through paths. The layer 2 (L2) cut-through path is over laid on the L1 cut-through path and the L2 cut-through path is used for IP data flows. Preferably, the L2 cut-through paths are defined as label switched paths (LSP) and the L1 cut-through paths are each an end-to-end path established with L1 cross connects associated with each switch.

Claims

1. A method of fault recovery for a network including the steps of:

establishing a physical topology for the network;

aligning a logical topology for the network with the physical such that a router at a L1 cut-though path end point views a L1 cut-through as a next hop; and

using a fault indication from the physical topology to effect fault recovery in the logical topology.

2. A method as claimed in claim 1 wherein the step of establishing comprises the step of defining a node in the network as a combination of a cross connect and a router.

3. A method as claimed in claim 2 wherein the step of establishing comprises the step of interconnecting network nodes via the respective cross connects.

4. A method as claimed in claim 3 wherein the step of aligning includes a step of establishing a logical link corresponding each physical connection between nodes.

5. A method as claimed in claim 1 wherein the step of using includes the step of defining an alternative path and corresponding physical connection for each primary route.

6. A method as claimed in claim 5 wherein the step of defining an alternative path includes the step of defining a layer 2 link.

7. A method as claimed in claim 6 wherein the layer 2 link is a label switched path.

8. A method as claimed in claim 7 wherein the label switched path is predetermined.

9. A method as claimed in claim 7 wherein the label switched path is defined at the time of the fault indication.

10. Apparatus for data networking comprising:

a cross connect for switching at a physical layer;

a router for redirecting data packets at a logical layer coupled to the cross connect; and

a fault recovery mechanism responsive to a fault indication in the physical layer for effecting a recovery in the logical layer.

11. Apparatus as claimed in claim 10 wherein the router includes an internetworking protocol (IP).

12. Apparatus as claimed in claim 11 wherein the cross connect is a synchronous optical network (SONET) add-drop multiplexor.

13. Apparatus as claimed in claim 11 wherein the cross connect is a time division multiplex (TDM) cross connect.

14. Apparatus as claimed in claim 11 wherein the internetworking protocol includes layer 3 routing.

15. Apparatus as claimed in claim 14 wherein the internetworking protocol includes layer 2 linking.

16. Apparatus as claimed in claim 15 wherein the internetworking protocol includes explicit route (ER) linking.

17. Apparatus as claimed in claim 16 wherein the internetworking protocol includes multi-protocol label switching (MPLS).

18. A network comprising:

a plurality of nodes, each node including a cross connect for switching at a physical layer, a router for redirecting data packets at a logical layer coupled to the cross connect and a fault recovery mechanism responsive to a fault indication in the physical layer for effecting a recovery in the logical layer;

a plurality of physical connections between nodes via the respective cross connects;

a plurality of logical routes between nodes via the respective routers; and

an alternative logical route for use by the fault recovery mechanism.

19. The network as claimed in claim 18 wherein the router includes an internetworking protocol (IP).

20. The network as claimed in claim 18 wherein the cross connect is a synchronous optical network (SONET) add-drop multiplexor.

21. The network as claimed in claim 18 wherein the cross connect is a time division multiplex (TDM) cross connect.

22. The network as claimed in claim 19 wherein the internetworking protocol includes layer 3 routing.

23. The network as claimed in claim 22 wherein the internetworking protocol includes layer 2 linking.

24. The network as claimed in claim 23 wherein the internetworking protocol includes explicit route (FR) linking.

25. The network as claimed in claim 24 wherein the internetworking protocol includes multi-protocol label switching (MPLS).

26. In a network including a plurality of nodes and having a plurality of communications layers, a method of providing fault recovery comprising the steps of:

aligning at least a first and second layer of the plurality of communications layers such that a router on the second layer at a L1 cut-through path end point views a L1 cut-through of the first layer as a next hop;

for a given path in the first layer, defining a corresponding path in the second layer and an alternative path in the second layer, the alternative path in the second layer corresponding to an alternative path in the first layer disjoint from the given path; and

on detection in the first layer of a fault in the given path. switching in the second layer from the corresponding path to the alternative path, whereby fault recovery in the network is provided in dependence upon speed of detection in the first layer.

27. A method as claimed in claim 26 wherein the first layer path is a physical connection between two nodes in the network.

28. A method as claimed in claim 27 wherein the physical connection is a cut-through path spanning several nodes in the network.

29. A method as claimed in claim 28 wherein the cut-through path is viewed as a next hop by a third layer of the plurality of communications layers.

30. A method as claimed in claim 26 wherein the second layer path is a label switched path.

31. A method as claimed in claim 27 wherein end points of the second layer path correspond to end points of the cut-through path.

32. A method as claimed in claim 26 wherein the alternative first layer path includes a first layer cut-through path between first and second nodes and a physical connection to a third node.

33. A method as claimed in claim 32 wherein the alternative second layer path uses the first layer cut-through path as a first hop.

34. A method as claimed in claim 26 wherein the given first layer path and the corresponding second layer path are designated as primary paths and the alternative first and second layer paths are designated as secondary paths.

35. A method as claimed in claim 34 wherein on the first designated path detecting that the fault no longer exists switching back to the primary paths.

36. A method as claimed in claim 26 wherein the step of switching in the second layer to provide fault recovery is independent of fault recovery in a third layer of the network.