Service Instance Applied to MPLS Networks

• US 20100124225A1
• Filed: 03/27/2009
• Published: 05/20/2010
• Est. Priority Date: 11/14/2008
• Status: Active Grant

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Fedyk, Donald
• Granted Patent: US 8,811,388 B2
• Time in Patent Office: Days
• US Class Current: 370/390
• CPC Class Codes: H04L 12/1886 with traffic restrictions for efficiency improvement, e.g. involving subnets or subdomains
• CPC Class Codes: H04L 41/12 Discovery or management of network topologies
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/026 Details of "hello" or keep-alive messages
• CPC Class Codes: H04L 45/03 by updating link state protocols
• CPC Class Codes: H04L 45/10 Routing in connection-oriented networks, e.g. X.25 or ATM
• CPC Class Codes: H04L 45/12 Shortest path evaluation
• CPC Class Codes: H04L 45/16 Multipoint routing
• CPC Class Codes: H04L 45/306 Route determination based on the nature of the carried application
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]
• CPC Class Codes: H04L 45/507 Label distribution
• CPC Class Codes: H04L 45/68 Pseudowire emulation, e.g. IETF WG PWE3

Abstract

Domain-wide unique node identifiers and domain-wide unique service identifiers are distributed within a MPLS domain using routing system LSAs. Nodes on the MPLS network compute shortest path trees for each destination and install unicast forwarding state based on the calculated trees. Nodes also install multicast connectivity between nodes advertising common interest in a common service identifier. Rather than distributing labels to be used in connection with unicast and multicast connectivity, the nodes deterministically calculate the labels. Any number of label contexts may be calculated. The labels may either be domain wide unique per unicast path or per multicast, or may be locally unique and deterministically calculated to provide forwarding context for the associated path. Multicast and unicast paths may be congruent, although this is not a requirement.

Claims

1. A method of enabling a service instance to be applied to an MPLS network, the method comprising the steps of:

exchanging routing advertisements by network elements in the MPLS network to enable the network elements to have a synchronized view of a topology of the MPLS network;

advertising, by a first MPLS network element on the MPLS network, a domain-wide unique service identifier in one of the routing advertisements; and

calculating, by a second MPLS network element from the second MPLS network element'"'"'s synchronized view of the topology of the MPLS network, whether to install forwarding state for the service identifier.

2. The method of claim 1, wherein the domain-wide unique service identifier is a domain-wide unique network element node Identifier.

3. The method of claim 2, wherein the node identifier is a domain-wide unique MPLS label.

4. The method of claim 3, wherein the domain-wide unique MPLS label may be used to forward unicast traffic to the first network element on the MPLS network.

5. The method of claim 4, wherein, if the second MPLS network element installs forwarding state for the service identifier, the second MPLS network element will install forwarding state for the domain-wide unique MPLS label such that any packet received by the second MPLS network element containing the domain-wide unique MPLS label will be forwarded toward the first MPLS network element.

6. The method of claim 1, wherein the step of calculating comprises determining whether the second MPLS network element is on a shortest path tree rooted at the first MPLS network element.

7. The method of claim 1, wherein further comprising calculating MPLS labels to be used to forward traffic associated with the service instance.

8. The method of claim 7, wherein the step of calculating MPLS labels comprises determining a domain-wide unique MPLS label that may be used to forward traffic associated with the service instance.

9. The method of claim 8, wherein the domain-wide unique MPLS label is a unicast label associated with the destination node on the MPLS network.

10. The method of claim 8, wherein the domain-wide unique MPLS label is a multicast label associated with a source of the multicast.

11. The method of claim 7, wherein the step of calculating MPLS labels comprises calculating labels to be used to forward traffic associated with the service instance in a deterministic manner.

12. The method of claim 1, wherein the step of calculating, by a second MPLS network element from the second MPLS network element'"'"'s synchronized view of the topology of the MPLS network, includes determining whether the same service identifier has been advertised by a third MPLS network element on the MPLS network and if so, determining whether the second MPLS network element is on a forwarding path between first MPLS network element and third MPLS network element.

13. The method of claim 12, wherein the third network element is multicast source associated with the service identifier, and wherein the first network element is a multicast subscriber associated with the service identifier.

14. The method of claim 12, wherein the forwarding path is a shortest path between the first MPLS network element and the third MPLS network element.

15. A method of enabling a service instance to be applied to an MPLS network, the method comprising the steps of:

advertising, by a subset of the MPLS network elements on the MPLS network, interest in a multicast service instance, the multicast service instance being a domain-wide unique value;

selectively installing, by each of the other network elements on the MPLS network, forwarding information for the multicast service instance, if the other network element is on a shortest path between two network elements advertising common interest in the same multicast service instance.

16. The method of claim 15, wherein the step of advertising is implemented via a link state routing system in use on the MPLS network.

17. The method of claim 15, wherein the forwarding information is a domain-wide unique label associated with the service instance, so that labels are not required to be signaled on the MPLS network to enable forwarding information to be installed by network elements on the MPLS network.

18. The method of claim 15, wherein the forwarding information is not domain-wide unique but is deterministically calculated by each of the nodes on the MPLS network, so that labels are not required to be signaled on the MPLS network to enable forwarding information to be installed by network elements on the MPLS network.

19. A MPLS network, comprising:

a plurality of MPLS nodes configured to run a link state routing protocol to enable each MPLS node to build a synchronized view of the MPLS network, the MPLS nodes being configured to advertise interest in service instances via the link state routing protocol and to install forwarding state between pairs of nodes advertising common interest in particular service instances, the MPLS nodes being further configured to calculate labels for use in connection with the forwarding state rather than signaling the labels for use in connection with the forwarding state.