Controlled distribution of inter-area routing information

• US 20070058568A1
• Filed: 09/14/2005
• Published: 03/15/2007
• Est. Priority Date: 09/14/2005
• 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
• Granted Patent: US 7,554,996 B2
• Time in Patent Office: Days
• US Class Current: 370/254
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]

Abstract

A technique controls distribution of 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 (“tail-end domain”) that is different (remote) from the domain of the head-end node (“head-end domain”). According to the inter-domain information distribution technique, the head-end node requests the remote reachability information from the tail-end node, which may employ an Interior Gateway Protocol (IGP) to transmit the information to a border router of the tail-end domain. The tail-end domain border router then shares this information with at least a head-end domain border router. The head-end node thereafter requests that the head-end domain border router release the reachability information into the head-end domain. 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 controlling distribution of 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 local domain of the head-end node, the method comprising:

requesting, from the head-end node, reachability information from the tail-end node;

transmitting, from the tail-end node, the reachability information via an Interior Gateway Protocol (IGP) advertisement to a border router of the remote domain (remote border router);

propagating the reachability information with one or more other border routers, at least one of the one or more other border routers being a border router in the local domain (local border router); and

requesting, from the head-end node, that the local border router release the reachability information into the local domain.

2. The method as in claim 1, further comprising:

leaking the reachability information from the local border router into the local domain in response to the request from the head-end node to release the reachability information.

3. The method as in claim 1, further comprising:

calculating, at the head-end node, routes reachable via the tail-end node through the TE-LSP; and

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

4. The method as in claim 1, further comprising:

indicating within the request for reachability information from the tail-end node that the tail-end node should respond using IGP advertisements.

5. The method as in claim 1, further comprising:

transmitting, from the tail-end node, the reachability information via the IGP advertisement in response to an indication within the request that the tail-end node should respond using a Resource ReSerVation Protocol (RSVP) message, in the event the reachability information is too large to fit within the RSVP message.

6. A system for controlling distribution of 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 local domain of the head-end node, the system comprising:

a reachability information request to send from the head-end node to the tail-end node;

an Interior Gateway Protocol (IGP) advertisement to transmit, from the tail-end node, the reachability information;

a border router of the remote domain (remote border router) to receive the IGP advertisement;

one or more other border routers to which the remote border router propagates the reachability information, at least one of the one or more other border routers being a border router in the local domain (local border router); and

a release request to be sent from the head-end node to the local border router to request that the local border router release the reachability information into the local domain.

7. The system as in claim 6, further comprising:

a controlled distribution table at the local border router, the controlled distribution table indicating whether to distribute the reachability information into the local domain.

8. An apparatus for controlling distribution of 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 local domain of the head-end node, the apparatus comprising:

means for requesting, from the head-end node, reachability information from the tail-end node;

means for transmitting, from the tail-end node, the reachability information via an Interior Gateway Protocol (IGP) advertisement to a border router of the remote domain (remote border router);

means for propagating the reachability information with one or more other border routers, at least one of the one or more other border routers being a border router in the local domain (local border router); and

means for requesting, from the head-end node, that the local border router release the reachability information into the local domain.

9. A computer readable medium containing executable program instructions for controlling distribution of 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 local domain of the head-end node, the executable program instructions comprising program instructions for:

requesting, from the head-end node, reachability information from the tail-end node;

transmitting, from the tail-end node, the reachability information via an Interior Gateway Protocol (IGP) advertisement to a border router of the remote domain (remote border router);

propagating the reachability information with one or more other border routers, at least one of the one or more other border routers being a border router in the local domain (local border router); and

requesting, from the head-end node, that the local border router release the reachability information into the local domain.

10. A method for controlling distribution of inter-domain routing information in a computer network, the method comprising:

storing inter-domain routing information at one or more border routers, the one or more border routers each contained within a single backbone domain and a respective local domain;

sharing the inter-domain routing information among the one or more border routers; and

leaking the inter-domain routing information from one of the one or more border routers into the respective domain in response to a request from a router within the respective domain for the inter-domain routing information.

11. The method as in claim 10, wherein the inter-domain routing information is selected from the group consisting of:

reachability information, Path Computation Element (PCE) Discovery information, and automesh group information.

12. The method as in claim 10, further comprising:

maintaining a controlled distribution table at the one or more border routers, the controlled distribution table indicating whether to distribute the inter-domain routing information into the respective domains.

13. A head-end node for use with controlling distribution of reachability information of a traffic engineering (TE) label switched path (LSP) in a computer network, the TE-LSP spanning multiple domains of the network, the head-end node comprising:

a network interface to i) send requests for reachability information to a tail-end node of the TE-LSP, the tail-end node residing in a remote domain, and ii) receive advertisements of the reachability information from a border router in a domain local to the node;

a processor coupled to the network interface and adapted to execute software processes; and

a memory adapted to store a head-end node process executable by the processor, the head-end node process configured to i) establish the TE-LSP to the tail-end node ii) request reachability information from the tail-end node, and iii) request that the reachability information be leaked into the local domain by the border router in the local domain.

14. A tail-end node for use with controlling distribution of reachability information of a traffic engineering (TE) label switched path (LSP) in a computer network, the TE-LSP spanning multiple domains of the network, the tail-end node comprising:

a network interface to i) receive requests for reachability information from a head-end node of the TE-LSP, the head-end node residing in a remote domain, and ii) send advertisements of the reachability information to a border router in a domain local to the node;

a processor coupled to the network interface and adapted to execute software processes; and

a memory adapted to store a tail-end node process executable by the processor, the tail-end node process configured to i) establish the TE-LSP from the head-end node ii) generate an advertisement containing reachability information of the node, and iii) send the reachability information to the border router in the local domain.

15. A border node for use with controlling distribution of reachability information of a traffic engineering (TE) label switched path (LSP) in a computer network, the TE-LSP spanning multiple domains of the network, the border node comprising:

a network interface to i) relay requests for reachability information from a head-end node of the TE-LSP to a tail-end node of the TE-LSP, the tail-end node residing in a domain that is remote from the local domain of the border node and head-end node, ii) receive advertisements of the reachability information from the tail-end node, and iii) receive requests that the reachability information be leaked into the local domain;

a processor coupled to the network interface and adapted to execute software processes; and

a memory adapted to store i) reachability information from one or more tail-end nodes, and ii) a border node process executable by the processor, the border node process configured to leak the reachability information of a particular tail-end node of the one or more tail-end nodes in response to a request that the reachability information for the particular tail-end node be leaked into the local domain.