Method and system for verifying connectivity of multi-segment pseudo-wires by tracing

1. A method of testing connectivity of a multi-segment pseudo-wire in a packet switched network, the method comprising:

sending an echo request message from a first provider edge device to a second provider edge device for a first segment of the multi-segment pseudo-wire between the first provider edge device and the second provider edge device;

receiving an echo reply message from the second provider edge device in response to the echo request message, the echo reply message confirming connectivity of the first segment and having a return code of either a first value or a second value;

for the return code of the first value, indicating whether there is a second segment in the multi-segment pseudo-wire between the second provider edge device and a third provider edge device; and,

including pseudo-wire information pertaining to the second segment in the echo reply message, wherein the sending, receiving, and indicating steps are repeated for each subsequent segment in the multi-segment pseudo-wire until the return code of the second value is received, indicating termination of the multi-segment pseudo-wire.

2. The method of claim 1 , wherein the first provider edge device has pseudo-wire information pertaining to the first segment.

3. The method of claim 2 , wherein the echo request message includes the pseudo-wire information pertaining to the first segment.

4. The method of claim 3 , wherein a second echo request message includes the pseudo-wire information pertaining to the second segment.

5. The method of claim 4 , wherein the packet switched network is a multiprotocol label switching (“MPLS”) network.

6. The method of claim 5 , wherein the pseudo-wire information pertaining to the first and second segments includes a type-length-value (“TLV”) for a pseudo-wire forwarding equivalence class (“FEC”).

7. The method of claim 1 , wherein the packet switched network includes first and second packet switched networks, wherein the first and second segments are in the first and second packet switched networks, respectively, and wherein the first and second packet switched networks are controlled by first and second service providers, respectively.

8. The method of claim 1 , wherein the second provider edge device is a k th provider edge device, the third provider edge device is a (k+1) th provider edge device, the first segment is a (k−1) th segment of n segments of the multi-segment pseudo-wire between the first provider edge device and the k th provider edge device, the second segment is a k th segment of the n segments of the multi-segment pseudo-wire between the k th provider edge device and the (k+1) th provider edge device, k and n are integers, and k is less than or equal to n.

9. A system that tests connectivity of a multi-segment pseudo-wire in a packet switched network, the system comprising:

a processor coupled to memory and to an interface to the packet switched network; and,

modules within the memory and executed by the processor, the modules including:

a first module that sends an echo request message from a first provider edge device to a second provider edge device containing pseudo-wire information of a first segment of the multi-segment pseudo-wire between the first provider edge device and the second provider edge device; and,

a second module that:

receives an echo reply message from the second provider edge device in response to the echo request message, the echo reply message confirming connectivity of the first segment and containing a return code of either a first value or a second value;

for the return code of the first value, indicating whether there is a second segment in the multi-segment pseudo-wire between the second provider edge device and a third provider edge device; and,

receives pseudo-wire information pertaining to the second segment in the echo reply message,

wherein the first module and the second module repeat the sending, receiving, and indicating for each subsequent segment in the multi-segment pseudo-wire until the return code of the second value is received, indicating termination of the multi-segment pseudo-wire.

10. The system of claim 9 , wherein second echo request message includes the pseudo-wire information pertaining to the second segment.

11. The system of claim 10 , wherein the packet switched network is a multiprotocol label switching (“MPLS”) network.

12. The system of claim 11 , wherein the pseudo-wire information pertaining to the first and second segments includes a type-length-value (“TLV”) for a pseudo-wire forwarding equivalence class (“FEC”).

13. The system of claim 9 , wherein the packet switched network includes first and second packet switched networks, wherein the first and second segments are in the first and second packet switched networks, respectively, and wherein the first and second packet switched networks are controlled by first and second service providers, respectively.

14. The system of claim 9 , wherein the second provider edge device is a k th provider edge device, the third provider edge device is a (k+1) th provider edge device, the first segment is a (k−1) th segment of n segments of the multi-segment pseudo-wire between the first provider edge device and the k th provider edge device, the second segment is a k th segment of the n segments of the multi-segment pseudo-wire between the k th provider edge device and the (k+1) th provider edge device, k and n are integers, and k is less than or equal to n.