DETECTION OF SPECIFIC BFD PATH FAILURES

• US 20080247324A1
• Filed: 04/06/2007
• Published: 10/09/2008
• Est. Priority Date: 04/06/2007
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Rahman, Reshad, Nadeau, Thomas D., Swallow, George, Prairie, Danny
• Granted Patent: US 8,374,164 B2
• Time in Patent Office: Days
• US Class Current: 370/245
• CPC Class Codes: H04L 41/12 Discovery or management of network topologies
• CPC Class Codes: H04L 45/02 Topology update or discovery
• 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]

Abstract

Improved detection of specific BFD LSP path failures is herein disclosed. The improved detection described herein allow for faster fault isolation of a failure along a LSP path, which in turn may allow for faster repair of the failure. When opening a BFD session with a LSP egress node, the LSP ingress node provides the LSP egress node a path descriptor along with the BFD Discriminator. If a BFD failure is detected at the LSP egress node, the LSP egress node can signal an alarm that includes a full description of the path.

Claims

1. Logic encoded in one or more tangible media for execution and, when executed, operable to perform operations of:

discovering a plurality of paths between an ingress node and an egress node;

constructing a path descriptor for each of the plurality of paths, wherein each path descriptor includes a plurality of node descriptors and each node descriptor includes a downstream IP address;

associating each path descriptor with a BFD discriminator that is locally-unique to the ingress node; and

for each of the plurality of paths, bootstrapping a BFD session with the LSP egress node, wherein the bootstrapping of the BFD session includes providing the egress node with the path descriptor and the associated BFD discriminator.

2. The logic of claim 1, wherein the discovered plurality of paths comprise a plurality of label switched paths (“

LSPs”

).

3. The logic of claim 1, wherein discovering a plurality of paths comprises:

performing a tree trace to discover all equal-cost multiple paths for a forwarding equivalence class.

4. The logic of claim 2, wherein bootstrapping a BFD session comprises:

sending a LSP-ping echo-request containing the path descriptor and the associated BFD discriminator to the LSP egress node.

5. The logic of claim 2, wherein bootstrapping a BFD session comprises:

providing the LSP egress node with the path descriptor in a type-length-value entry.

6. The logic of claim 2, wherein bootstrapping a BFD session comprises:

providing the LSP egress node with the path descriptor in a type-length-value entry that also includes a field indicating the number of node descriptors in the path descriptor.

7. The logic of claim 2, wherein bootstrapping a BFD session comprises:

providing the LSP egress node with the path descriptor in a type-length-value entry that also includes an address-type field indicating the address type and length of the downstream IP addresses as well as the length of any downstream interface fields.

9. The logic of claim 7, wherein the path is a label switched path.

8. Logic encoded in one or more tangible media for execution and, when executed, operable to perform operations of:

bootstrapping a BFD session with an ingress node of a path, wherein the bootstrapping includes receiving, from the path'"'"'s ingress node, a path descriptor for the path and a BFD discriminator associated with the path descriptor, wherein the path descriptor includes a plurality of node descriptors and each node descriptor includes a downstream IP address;

detecting a failure in the BFD session; and

signaling an alarm to indicate the detected failure, wherein the alarm includes the path descriptor for the path and the associated BFD discriminator.

10. The logic of claim 8, wherein bootstrapping a BFD session comprises:

receiving a LSP-ping echo-request containing the path descriptor and the associated BFD discriminator from the LSP ingress node.

11. The logic of claim 8, wherein bootstrapping a BFD session comprises:

receiving, from the LSP ingress node, the path descriptor in a type-length-value entry.

12. The logic of claim 8, wherein bootstrapping a BFD session comprises:

receiving, from the LSP ingress node, the path descriptor in a type-length-value entry that also includes a field indicating the number of node descriptors in the path descriptor.

13. The logic of claim 8, wherein bootstrapping a BFD session comprises:

receiving, from the LSP ingress node, the path descriptor in a type-length-value entry that also includes an address-type field indicating the address type and length of the downstream IP addresses as well as the length of any downstream interface fields.