Label switched path OAM wrapper
View Patent ↗Methods and devices for logically segmenting an LSP so that OAM DTUs may be used to determine the performance and/or the status of LSP segments. To segment a previously determined LSP, a dedicated subpath (a logical LSP) within that predetermined LSP is defined between two LSRs that are capable of processing OAM DTUs. The source node (source LSR) establishes a logical LSP between itself and the destination node (destination LSR) using an LDP. In doing this, the logical LSP traverses a specific path and transits through specific nodes in that path. The source node then transmits an OAM DTU or any other specialized DTU to the destination node using a label specifically associated with the logical LSP that was established. The characteristic of the specific path traversed by the logical LSP can thus be determined by when, how, and if the specialized DTU is received by the destination node.
1. A method of processing an operation and maintenance (OAM) data transmission unit (DTU) in a multi-protocol label switched (MPLS) network at an intermediate node between a source node and a destination node of a first label switched path (LSP), the source node, destination node and intermediate node being capable of processing OAM DTUs, the method comprising:
receiving a DTU at the intermediate node, the intermediate node being a defined end point of a second LSP that comprises a segment of the first LSP;
identifying that a top level label of the DTU is a label assigned to the second LSP;
determining that the DTU has been received on the second LSP based on the label assigned to the second LSP; and
in response to identifying the label assigned to the second LSP, determining that a label in the DTU following the label assigned to the second LSP is a label indicating that the DTU is an OAM DTU.
2. The method of claim 1 further comprising removing the label assigned to the second LSP.
3. The method of claim 1 wherein the OAM DTU comprises a time stamp.
4. The method of claim 3 further comprising determining a transit time of the OAM DTU based on the time stamp.
5. The method of claim 1 wherein the OAM DTU is transmitted by the source node.
6. The method of claim 1 further comprising calculating a performance of the segment of the first LSP based on data contained in the OAM DTU.
7. The method of claim 1 wherein the second LSP is established using a Label Distribution Protocol.
8. The method of claim 1 further comprising determining that the label indicating that the DTU is an OAM DTU is a last label in the DTU.
9. The method of claim 1 wherein the label indicating that the DTU is an OAM DTU is an OAM label.
10. An intermediate node between a source node and a destination node of a first label switched path (LSP), the source node, destination node and intermediate node being configured to process operation and maintenance (OAM) data transmission units (DTUs), the intermediate node comprising:
an interface configured to receive a DTU, the intermediate node being a defined end point of a second LSP that comprises a segment of the first LSP; and
a processor configured to:
identify that a top level label of the DTU is a label assigned to the second LSP;
determine that the DTU has been received on the second LSP based on the label assigned to the second LSP; and
in response to identifying the label assigned to the second LSP, determine that a label in the DTU following the label assigned to the second LSP is a label indicating that the DTU is an OAM DTU.
11. The intermediate node of claim 10 wherein the processor is further configured to remove the label assigned to the second LSP.
12. The intermediate node of claim 10 wherein the processor is further configured to identify a time stamp in the OAM DTU.
13. The intermediate node of claim 12 wherein the processor is further configured to determine a transit time of the OAM DTU based on the time stamp.
14. The intermediate node of claim 10 wherein the processor is further configured to calculate a performance of the segment of the first LSP based on data contained in the OAM DTU.
15. The intermediate node of claim 10 wherein the second LSP is established using a Label Distribution Protocol.
16. The intermediate node of claim 10 wherein the processor is further configured to determine that the label indicating that the DTU is an OAM DTU is a last label in the DTU.
17. The intermediate node of claim 10 wherein the label indicating that the DTU is an OAM DTU is an OAM label.
18. A system for measuring the performance of a segment of a first Label Switched Path (LSP) in a multi-protocol label switched (MPLS) network, the system comprising:
a source and destination node of a first LSP that are configured to process operation and maintenance(OAM) data transmission units (DTUs); and
an intermediate node that is configured to process OAM DTUs and is the defined end point of a second LSP that comprises a segment of the first LSP, the intermediate node also configured to:
receive a DTU;
identify that a top level label of the DTU is a label assigned to the second LSP;
determine that the DTU has been received on the second LSP based on the label assigned to the second LSP; and
in response to identifying the label assigned to the second LSP, determine that a next label in the DTU following the label assigned to the second LSP is a label indicating that the DTU is an OAM DTU.
19. The system of claim 18 wherein the intermediate node is further configured to remove the label assigned to the second LSP.
20. The system of claim 18 wherein the intermediate node is further configured to identify a time stamp in the OAM DTU.
21. The system of claim 20 wherein the intermediate node is further configured to determine a transit time of the OAM DTU based on the time stamp.
22. The system of claim 18 wherein the source node is configured to transmit the OAM DTU.
23. The system of claim 18 wherein the intermediate node is further configured to calculate a performance of the segment of the first LSP based on data contained in the OAM DTU.
24. The system of claim 18 wherein the second LSP is established using a Label Distribution Protocol.
25. The system of claim 18 wherein the intermediate node is further configured to determine whether the label indicating the DTU is an OAM DTU is a last label in the DTU.
26. A network router for routing data transmission units (DTUs) in a domain which only allows unidirectional flow, the router including:
a receiving module configured to receive DTUs;
a transmitting module configured to transmit DTUs;
a switch core module placed between the receiving module and the transmitting module, the switch core module configured to route DTUs between the receiving and the transmitting modules; and
a diagnostic module configured to determine a performance of a network path of the domain, the diagnostic module further configured to process specialized DTUs received by the receiving module and create specialized DTUs to be transmitted by the transmitting module,
the router being configured to execute computer readable and computer executable instructions for implementing a method for determining the performance of the network path, the method including:
a) if the network router is a source node for the network path, transmitting the specialized DTUs to a destination node; and
b) if the network router is a destination node for the network path, receiving the specialized DTUs and performing an action chosen from a group consisting of:
b1) calculating a performance of the network path based on data contained in the specialized DTU; and
b2) determining if there is a fault on the network path based on whether a specialized DTU is received within a given amount of time.
27. The network router of claim 26 wherein the network path is in a multi-protocol label switched (MPLS) network.
28. The network router of claim 27 wherein the specialized DTU is an operation and maintenance (OAM) DTU.
29. The network router of claim 26 wherein the specialized DTU is an operation and maintenance (OAM) DTU.