Inter-domain TE-LSP with IGP extensions

• US 7,460,481 B2
• Filed: 12/01/2004
• Issued: 12/02/2008
• Est. Priority Date: 12/01/2004
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Vasseur, Jean-Philippe, Previdi, Stefano B.
• Primary Examiner(s): Moore, Jr.; Michael J
• Application Number:
  US11/001,459
• Publication Number:
  US 20060114916A1
• Time in Patent Office: 1,462 Days
• Field of Search: None
• US Class Current: 370/238
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/04 Interdomain routing, e.g. hierarchical routing
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04L 45/502 Frame based
• CPC Class Codes: H04L 47/70 Admission control; Resource allocation
• CPC Class Codes: H04L 47/724 at intermediate nodes, e.g. resource reservation protocol [RSVP]
• CPC Class Codes: H04L 47/785 among multiple network domains, e.g. multilateral agreements
• CPC Class Codes: H04L 47/825 Involving tunnels, e.g. MPLS

Abstract

A technique propagates reachability information for a tail-end node of a traffic engineering (TE) label switched path (LSP) to a head-end node of the TE-LSP in a computer network. The TE-LSP preferably spans multiple domains of the network such that the tail-end node resides in a domain that is different (remote) from the domain of the head-end node. The inter-domain information propagation technique employs an Interior Gateway Protocol (IGP) to transmit the remote reachability information from a target node residing in the same domain as the tail-end node to the head-end node. The head-end node uses the remote information to calculate routes, i.e., address prefixes and associated attributes, reachable from the tail-end node for insertion into its routing table.

Claims

1. A method for propagating reachability information for a tail-end node of a traffic engineering (TE) label switched path (LSP) to a head-end node of the TE-LSP in a computer network, the TE-LSP spanning multiple domains of the network such that the tail-end node resides in a domain that is remote from the domain of the head-end node, the method comprising:

transmitting, via an Interior Gateway Protocol (IGP) advertisement, the reachability information from the target node residing in the domain of the tail-end node to the head-end node;

receiving, at the head-end node, the transmitted reachability information;

calculating, at the head-end node, routes reachable from the tail-end node using the received information; and

inserting the calculated routes into a routing table of the head-end node.

2. The method of claim 1, further comprising:

advertising a reachable address prefix from the target node using an area-identifier (area-id) data structure that identifies the domain to which each prefix belongs.

3. The method of claim 2, further comprising:

transmitting an extended reachability object data structure within the IGP advertisement, the extended reachability object data structure containing the area-id data structure.

4. The method of claim 1, further comprising:

advertising a reachable address prefix that is downstream from the tail-end node in its domain using a node-id data structure that identifies the tail-end node as originating the prefix.

5. The method of claim 4, further comprising:

transmitting an extended reachability object data structure within the IGP advertisement across the domains, the extended reachability object data structure containing the node-id data structure.

6. The method of claim 5, further comprising:

advertising a metric of each reachable address prefix from the tail-end node using a prefix-cost data structure that contains the metric as computed by a node that does not originate the prefix.

7. The method of claim 6, further comprising:

transmitting the extended reachability object data structure within the IGP advertisement across the domains, the extended reachability object data structure containing the prefix-cost data structure.

8. The method of claim 1, further comprising:

storing the received reachability information in a shadow routing table at the head-end node prior to calculating routes.

9. The method of claim 1, wherein the TE-LSP spans multiple areas.

10. A system for propagating reachability information for a tail-end node of a traffic engineering (TB) label switched path (LSP) to a head-end node of the TE-LSP in a computer network, the TE-LSP spanning multiple domains of the network such that the tail-end node resides in a domain that is remote from the domain of the head-end node, the system comprising:

an Interior Gateway Protocol (IGP) advertisement configured to carry the reachability information from a target node residing in a domain of the tail-end node to the head-end node;

a memory of the head-end node configured to store received reachability information;

a processor of the head-end node implementing a routing information base (RIB) to calculate routes reachable from the tail-end node using the received reachability information; and

the memory of the head-end node further configured to maintain a routing table of the head-end node that stores the calculated routes.

11. The system of claim 10, further comprising:

an area-identifier (area-id) data structure to advertise a reachable address prefix from the target node, wherein the area-id data structure identifies the domain to which each prefix belongs.

12. The system of claim 11, further comprising:

an extended reachability object data structure within the IGP advertisement to transmit the area-id data structure.

13. The system of claim 10, further comprising:

a node-id data structure to advertise a reachable address prefix that is downstream from the tail-end node in its domain, wherein the node-id data structure identifies the tail-end node as originating the prefix.

14. The system of claim 13, further comprising:

an extended reachability object data structure within the IGP advertisement to transmit, across the domains, the node-id data structure.

15. The system of claim 10, further comprising:

a prefix-cost data structure to advertise a metric of each reachable address prefix from the tail-end node, wherein the prefix-cost data structure contains the metric as computed by a node that does not originate the prefix.

16. The system of claim 15, further comprising:

an extended reachability object data structure within the IGP advertisement to transmit, across the domains, the prefix-cost data structure.

17. The system of claim 10, further comprising:

the memory of the head-end node further configured to maintain a shadow routing table that stores the received reachability information prior to use of the information in calculating routes.

18. An apparatus for propagating reachability information for a tail-end node of a traffic engineering (TE) label switched path (LSP) to a head-end node of the TE-LSP in a computer network, the TE-LSP spanning multiple domains of the network such that the tail-end node resides in a domain that is remote from the domain of the head-end node, the apparatus comprising:

means for transmitting, via an Interior Gateway Protocol (IGP) advertisement, the reachability information from the target node residing in the domain of the tail-end node to the head-end node;

means for receiving, at the head-end node, the transmitted reachability information;

means for calculating, at the head-end node, routes reachable from the tail-end node using the received information; and

means for inserting the calculated routes into a routing table of the head-end node.

19. A computer readable medium containing executable program instructions for propagating reachability information for a tail-end node of a traffic engineering (TE) label switched path (LSP) to a head-end node of the TE-LSP in a computer network, the TE-LSP spanning multiple domains of the network such that the tail-end node resides in a domain that is remote from the domain of the head-end node, the executable program instructions comprising program instructions for:

transmitting, via an Interior Gateway Protocol (IGP) advertisement, the reachability information from the target node residing in the domain of the tail-end node to the head-end node;

receiving, at the head-end node, the transmitted reachability information;

calculating, at the head-end node, routes reachable from the tail-end node using the received information; and

inserting the calculated routes into a routing table of the head-end node.