System and Method for Computing a Backup Ingress of a Point-to-Multipoint Label Switched Path

• US 20110211445A1
• Filed: 02/23/2011
• Published: 09/01/2011
• Est. Priority Date: 02/26/2010
• Status: Active Grant

• Current Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Inventors: Chen, Huaimo
• Granted Patent: US 8,885,459 B2
• Time in Patent Office: Days
• US Class Current: 370/221
• CPC Class Codes: H04L 45/16 Multipoint routing
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04L 45/42 Centralised routing
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]

Abstract

Disclosed is an apparatus that includes a path computation element (PCE) configured to communicate with a path computation client (PCC) and compute a backup ingress node for a Point-to-Multipoint (P2MP) Label Switched Path (LSP) in a network associated with the PCC. The backup ingress node is coupled to an ingress node of the P2MP LSP and to a plurality of next-hop nodes of the ingress node of the P2MP LSP via a backup tree.

Claims

1. An apparatus comprising:

a path computation element (PCE) configured to communicate with a path computation client (PCC) and compute a backup ingress node for a Point-to-Multipoint (P2MP) Label Switched Path (LSP) in a network associated with the PCC,

wherein the backup ingress node is coupled to an ingress node of the P2MP LSP and to a plurality of next-hop nodes of the ingress node of the P2MP LSP via a backup tree.

2. The apparatus of claim 1, wherein the backup ingress node and the ingress node are both coupled to an external node, and wherein the backup node is configured to ensure data delivery in the P2MP LSP when the ingress node fails.

3. The apparatus of claim 2, wherein the PCE is further configured to communicate with a second PCE associated with the external node'"'"'s network to obtain a list of candidate backup ingress nodes;

wherein each of the candidate backup ingress nodes satisfies one or more constraints from the external node to the candidate backup node.

4. The apparatus of claim 3, wherein a candidate backup ingress node is a node in the same network as the ingress node of the P2MP LSP.

5. The apparatus of claim 3, wherein the constraints compromise a hop limit, bandwidth and metric constraints on the path from the external node to a candidate backup ingress node.

6. The apparatus of claim 3, wherein the PCE is configured to receive the list of the candidate backup ingress nodes from the second PCE and select a backup ingress node from the list that satisfies a set of constraints.

7. The apparatus of claim 6, wherein the constraints compromise exclusive constraints, a hop limit, and bandwidth and metric constraints on the sub tree from the backup ingress node to the next-hop nodes of the ingress node of the P2MP LSP.

8. The apparatus of claim 6, wherein the constraints compromise a hop limit constraints on the path between the backup ingress node and the ingress node of the P2MP LSP.

9. The apparatus of claim 6, wherein the PCE is configured to send the PCC the backup ingress node and the sub tree path from the backup ingress node to the next-hop nodes of the ingress node of the P2MP LSP.

10. The apparatus of claim 1, wherein the ingress node is configured to receive the backup ingress node and the sub tree path from the PCC and communicate with the backup ingress node, and wherein the backup ingress node establishes a backup P2MP sub tree that merges into the P2MP LSP at the next-hop nodes of the ingress node, wherein the backup P2MP sub tree is from the backup ingress node to the next-hop nodes.

11. A network component comprising:

a receiver configured to receive a request message for computing a backup ingress node of a Point-to-Multipoint (P2MP) Label Switched Path (LSP) in a network;

a circuit logic configured to attempt computing a backup ingress node for the P2MP LSP based on the network'"'"'s topology and a set of constraints in the request message; and

a transmitter configured to send a reply message comprising the computed backup ingress node if the backup ingress node is computed successfully.

12. The network component of claim 11, wherein the request message, the reply message, or both comprise a request parameter (RP) object that comprises a reserved field, a plurality of flags, a request identification (ID) number, and one or more optional type-length-values (TLVs), and wherein the flags comprise a backup ingress bit (I) flag, a fragmentation bit (F) flag, a P2MP bit (N) flag, an Explicit Route Object (ERO) compression bit (E) flag, a strict/loose bit (O) flag, a bi-directional bit (B) flag, a re-optimization (R) flag, and a plurality of priority bit (P) flags.

13. The network component of claim 11, wherein the constraints comprise bandwidth limitation and information about an external node that transmits traffic to an ingress node of the P2MP LSP.

14. The network component of claim 11, wherein if the attempt to compute the backup ingress node fails, a reply message is sent to indicate a reason for failure to compute the backup ingress node.

15. The network component of claim 14, wherein the reply message comprises a PCE Protocol (PCEP) Error object that indicates an error related to the backup ingress node computation, and wherein the PCEP Error object comprises a flags field, an error-type field, an error-value field, and one or more optional type-length-value (TLVs).

16. The network component of claim 14, wherein the reply message comprises a NO-PATH object that indicates a reason of failure to compute the backup ingress node, wherein the NO-PATH object comprises a nature of issue field, a flags field that comprises a capability (C) flag, a first optional type-length-value (TLV), and one or more second optional TLVs, and wherein the first optional TLV comprises a type field, a length field, and a second flags field that comprises a reachability (R) flag.

17. The network component of claim 16, wherein the R flag is set to indicate a reachability issue with one or more next-hops of an ingress node of the P2MP LSP from a candidate backup ingress node, and wherein the NO-PATH object comprises a plurality of unreachable Internet Protocol (IP) version four (IPv4) or IP version six (IPv6) next-hops TLVs that list IP addresses of the next-hops of the ingress node of the P2MP LSP that are not reachable from the candidate backup ingress node.

18. A method comprising:

exchanging capability information between a path computation element (PCE) and a path computation client (PCC) during a session establishment between the PCE and the PCC,

wherein the capability information are related to computing a backup ingress node for a Point-to-Multipoint (P2MP) Label Switched Path (LSP) in a network.

19. The method of claim 18, wherein the capability information are sent by the PCE in a PCE capability sub type-length-value (TLV) in a PCE Discovery (PCED) TLV, wherein the PCE capability sub TLV comprises a type field, a length field, and a value field that comprises a first flag and a second flag, and wherein the first flag is set to indicate that the PCE is capable of computing a backup ingress node for a P2MP LSP and the second flag is set to indicate that the PCE is capable of computing a backup ingress node for a Point-to-Point (P2P) LSP.

20. The method of claim 18, wherein the capability information are sent by the PCC in PCE capability TLV in an open object message to discover the capability information, and wherein the PCE capability TLV comprises a type field, a length field, and a value field that indicates a capability to compute a backup ingress node for the P2MP LSP.