Detecting data plane liveliness of a label-switched path

Claim 2

For use with an ingress node of a label-switched path, a method for testing liveliness of the label-switched path comprising: a) generating information related to requesting a reply from a downstream node on the label-switched path, wherein the information identifies a relationship between the downstream node and the label-switched path; b) inserting the generated information into a request message; c) forwarding the request message over the label-switched path; d) determining whether or not a reply to the request message is received within a predetermined time; and e) if no reply to the request message is received within the predetermined time, concluding that the label-switched path is not functioning and implementing a first responsive policy, wherein the generated information specifies one of a data plane return path and a control plane return path to be used by the reply.

Claim 3

The method of claim 1 further comprising: f) if a reply to the request message is received within the predetermined time, then i) examining information inserted into the reply by a replying downstream node, and ii) if the information inserted into the reply indicates a problem with the label-switched path, then implementing a second responsive policy.

Claim 4

The method of claim 1 wherein the generated information specifies one of a connectivity test mode and a fault isolation test mode.

Claim 5

The method of claim 1 wherein the generated information specifies type of return path to be used by the reply.

Claim 6

The method of claim 1 wherein the data plane return path is a routed path.

Claim 7

The method of claim 1 wherein the first responsive policy includes at least one of (A) isolating a point of failure in the label-switched path, (B) marking the label-switched path as failed, (C) activating a backup label-switched path, (D) determining a new label-switched path, (E) determining a new label-switched path subject to a constraint of avoiding a point of failure isolated in the label-switched path, and (F) determining an alternative communication means to an egress node of the failed LSP.

Claim 8

The method of claim 1 wherein the generated information includes a unique identifier such that a reply to the request message can be associated with the request message.

Claim 9

The method of claim 7 wherein the unique identifier includes at least one of a sequence number and a time stamp.

Claim 10

A machine-readable medium having stored thereon machine-executable instructions which, when executed by a machine, perform the method of claim 1 .

Claim 11

For use with an ingress node of a label-switched path, apparatus for testing liveliness of the label-switched path comprising: a) a test facility for i) generating information related to requesting a reply from a downstream node on the label-switched path, wherein the information identifies the label-switched path being tested, and ii) inserting the generated information into a request message; b) a forwarding engine for forwarding the request message over the label-switched path; and c) a diagnostic facility for i) determining whether or not a reply to the request message is received within a predetermined time; and ii) if no reply to the request message is received within the predetermined time, concluding that the label-switched path is not functioning and implementing a first responsive policy, wherein the generated information specifies one of a data plane return path and a control plane return path to be used by the reply.

Claim 12

For use with an ingress node of a label-switched path, apparatus for testing liveliness of the label-switched path comprising: a) a test facility for i) generating information related to requesting a reply from a downstream node on the label-switched path, wherein the information identifies the label-switched path being tested, and ii) inserting the generated information into a request message; b) a forwarding engine for forwarding the request message over the label-switched path; and c) a diagnostic facility for i) determining whether or not a reply to the request message is received within a predetermined time; and ii) if no reply to the request message is received within the predetermined time, concluding that the label-switched path is not functioning and implementing a first responsive policy, wherein the generated information specifies one of a data plane return path and a control plane return path to be used by the reply.

Claim 13

The apparatus of claim 10 wherein the diagnostic facility is further adapted for iii) if a reply to the request message is received within the predetermined time, then A) examining information inserted into the reply by the downstream node, and B) if the information inserted into the reply indicates a problem with the label-switched path, then implementing a second responsive policy.

Claim 14

The apparatus of claim 10 wherein the generated information specifies one of a connectivity test mode and a fault isolation test mode.

Claim 15

The apparatus of claim 10 wherein the generated information specifies type of return path to be used by the reply.

Claim 16

The apparatus of claim 10 wherein the data plane return path is a routed path.

Claim 17

The apparatus of claim 10 wherein the first responsive policy includes at least one of (A) isolating a point of failure in the label-switched path, (B) marking the label-switched path as failed, (C) activating a backup label-switched path, (D) determining a new label-switched path, (E) determining a new label-switched path subject to a constraint of avoiding a point of failure isolated in the label-switched path, and (F) determining an alternative communication means to an egress node of the failed LSP.

Claim 18

For use with a node, a method for replying to a request related to testing liveliness of a label-switched path, the method comprising: a) generating information related to replying to the request from an upstream node on the label-switched path, the information including an indication of a relationship between the node and the label-switched path being tested; b) inserting the generated information into a reply message; and c) forwarding the reply message, back to a node that sourced the request, over a path or route other than the label-switched path, wherein the indication of a relationship between the node and the label-switched path indicates a relationship selected from a group of relationships consisting of (A) the replying node is an egress node for a forwarding equivalency class bound to the label-switched path, (B) the replying node has no mapping for the forwarding equivalency class bound to the label-switched path, (C) the replying node does not belong to a set of downstream routers earlier identified by an upstream node of the label-switched path, (D) the replying node belongs to a set of downstream routers earlier identified by an upstream node of the label-switched path and its label mapping for the forwarding equivalency class bound to the label-switched path is as expected, and (E) the replying node belongs to a set of downstream routers earlier identified by an upstream node of the label-switched path and but its label mapping for the forwarding equivalency class bound to the label-switched path is not as expected.

Claim 19

For use with a node, a method for replying to a request related to testing liveliness of a label-switched path, the method comprising: a) generating information related to replying to the request from an upstream node on the label-switched path, the information including an indication of a relationship between the node and the label-switched path being tested; b) inserting the generated information into a reply message; and c) forwarding the reply message, back to a node that sourced the request, over a path or route other than the label-switched path, wherein the indication of a relationship between the node and the label-switched path indicates a relationship selected from a group of relationships consisting of (A) the replying node is an egress node for a forwarding equivalency class bound to the label-switched path, (B) the replying node has no mapping for the forwarding equivalency class bound to the label-switched path, (C) the replying node does not belong to a set of downstream routers earlier identified by an upstream node of the label-switched path, (D) the replying node belongs to a set of downstream routers earlier identified by an upstream node of the label-switched path and its label mapping for the forwarding equivalency class bound to the label-switched path is as expected, and (E) the replying node belongs to a set of downstream routers earlier identified by an upstream node of the label-switched path and but its label mapping for the forwarding equivalency class bound to the label-switched path is not as expected.

Claim 20

For use with a node, a method for replying to a request related to testing liveliness of a label-switched path, the method comprising: a) generating information related to replying to the request from an upstream node on the label-switched path, the information including an indication of a relationship between the node and the label-switched path being tested; b) inserting the generated information into a reply message; and c) forwarding the reply message, back to a node that sourced the request, over a path or route other than the label-switched path, wherein the request includes a reply mode to be used, and wherein the path or route used to forward the reply message back to a node that sourced the request depends on the reply mode specified in the request.

Claim 21

For use with a node, a method for replying to a request related to testing liveliness of a label-switched path, the method comprising: a) generating information related to replying to the request from an upstream node on the label-switched path, the information including an indication of a relationship between the node and the label-switched path being tested; b) inserting the generated information into a reply message; and c) forwarding the reply message, back to a node that sourced the request, over a path or route other than the label-switched path, wherein the request includes a reply mode to be used, and wherein the path or route used to forward the reply message back to a node that sourced the request depends on the reply mode specified in the request.

Claim 22

The method of claim 17 wherein the path or route is a routed path on the data plane.

Claim 23

The method of claim 18 wherein the reply message is a UDP packet.

Claim 24

The method of claim 18 wherein the reply message is a UDP packet with a router alert Internet protocol option set.

Claim 25

The method of claim 17 wherein the path or route is a routed path used by the control plane.

Claim 26

The method of claim 21 wherein the label-switched path is controlled using the RVSP protocol, and wherein the reply message is an RESV message.

Claim 27

The method of claim 21 wherein the label-switched path is controlled using the LDP protocol, and wherein the reply message is a label mapping message.

Claim 28

The method of claim 21 wherein the label-switched path is controlled using the BGP protocol, and wherein the reply message is a selected one of (A) a notification message and (B) a network layer reachability information message.

Claim 29

The method of claim 17 wherein the information generated includes an identifier of the label-switched path.

Claim 30

The method of claim 17 further comprising: checking a hop count of the request; and if the hop count is a predetermined value, then determining immediately adjacent downstream nodes on the label-switched path, wherein the information generated includes an indication of the immediately adjacent downstream nodes.

Claim 31

A machine-readable medium having stored thereon machine-executable instructions which, when executed by a machine, perform the method of claim 17 .

Claim 32

For use with a node, apparatus for replying to a request related to testing liveliness of a label-switched path, the apparatus comprising: a) a test facility for i) generating information related to replying to the request from an upstream node on the label-switched path, the information including an indication of a relationship between the node and the label-switched path being tested, and ii) inserting the generated information into a reply message; and b) a forwarding engine for forwarding the reply message, back to a node that sourced the request, over channel other than the label-switched path, wherein the indication of a relationship between the node and the label-switched path indicates a relationship selected from a group or relationships consisting of (A) the replying node is an egress node for a forwarding equivalency class bound to the label-switched path, (B) the replying node has no mapping for the forwarding equivalency class bound to the label-switched path, (C) the replying node does not belong to a set of downstream routers earlier identified by an upstream node of the label-switched path, (D) the replying node belongs to a set of downstream routers earlier identified by an upstream node of the label-switched path and its label mapping for the forwarding equivalency class bound to the label-switched path is as expected, and (E) the replying node belongs to a set of downstream routers earlier identified by an upstream node of the label-switched path and but its label mapping for the forwarding equivalency class bound to the label-switched path is not as expected.

Claim 33

For use with a node, apparatus for replying to a request related to testing liveliness of a label-switched path, the apparatus comprising: a) a test facility for i) generating information related to replying to the request from an upstream node on the label-switched path, the information including an indication of a relationship between the node and the label-switched path being tested, and ii) inserting the generated information into a reply message; and b) a forwarding engine for forwarding the reply message, back to a node that sourced the request, over channel other than the label-switched path, wherein the indication of a relationship between the node and the label-switched path indicates a relationship selected from a group or relationships consisting of (A) the replying node is an egress node for a forwarding equivalency class bound to the label-switched path, (B) the replying node has no mapping for the forwarding equivalency class bound to the label-switched path, (C) the replying node does not belong to a set of downstream routers earlier identified by an upstream node of the label-switched path, (D) the replying node belongs to a set of downstream routers earlier identified by an upstream node of the label-switched path and its label mapping for the forwarding equivalency class bound to the label-switched path is as expected, and (E) the replying node belongs to a set of downstream routers earlier identified by an upstream node of the label-switched path and but its label mapping for the forwarding equivalency class bound to the label-switched path is not as expected.

Claim 34

For use with a node, apparatus for replying to a request related to testing liveliness of a label-switched path, the apparatus comprising: a) a test facility for i) generating information related to replying to the request from an upstream node on the label-switched path, the information including an indication of a relationship between the node and the label-switched path being tested, and ii) inserting the generated information into a reply message; and b) a forwarding engine for forwarding the reply message, back to a node that sourced the request, over channel other than the label-switched path, wherein the request includes a reply mode to be used, and wherein the path or route used by the forwarding engine to forward the reply message back to a node that sourced the request depends on the reply mode specified in the request.

Claim 35

For use with a node, apparatus for replying to a request related to testing liveliness of a label-switched path, the apparatus comprising: a) a test facility for i) generating information related to replying to the request from an upstream node on the label-switched path, the information including an indication of a relationship between the node and the label-switched path being tested, and ii) inserting the generated information into a reply message; and b) a forwarding engine for forwarding the reply message, back to a node that sourced the request, over channel other than the label-switched path, wherein the request includes a reply mode to be used, and wherein the path or route used by the forwarding engine to forward the reply message back to a node that sourced the request depends on the reply mode specified in the request.

Claim 36

The apparatus of claim 29 wherein the path or route is a routed path on the data plane.

Claim 37

The apparatus of claim 30 wherein the reply message is a UDP packet.

Claim 38

The apparatus of claim 30 wherein the reply message is a UDP packet with a router alert Internet protocol option set.

Claim 39

The apparatus of claim 29 wherein the path or route is a routed path used by the control plane.

Claim 40

The apparatus of claim 33 wherein the label-switched path is controlled using the RVSP protocol, and wherein the reply message is an RESV message.

Claim 41

The apparatus of claim 33 wherein the label-switched path is controlled using the LDP protocol, and wherein the reply message is a label mapping message.

Claim 42

The apparatus of claim 33 wherein the label-switched path is controlled using the BGP protocol, and wherein the reply message is a selected one of (A) a notification message and (B) a network layer reachability information message.

Claim 43

The apparatus of claim 29 wherein the information generated includes an identifier of the label-switched path.

Claim 44

The apparatus of claim 29 further comprising: means for checking a hop count value of the request; and a control facility for determining immediately adjacent downstream nodes on the label-switched path if the hop count value is a predetermined value, wherein the information generated includes an indication of the immediately adjacent downstream nodes.