Method to reduce routing convergence at the edge

• US 20100061227A1
• Filed: 09/30/2008
• Published: 03/11/2010
• Est. Priority Date: 09/11/2008
• Status: Active Grant

• Current Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Original Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Inventors: Sundt, Mark, Uttaro, James
• Granted Patent: US 8,174,967 B2
• Time in Patent Office: Days
• US Class Current: 370/221
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00
• CPC Class Codes: H04L 45/04 Interdomain routing, e.g. hierarchical routing
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/28 using route fault recovery
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]

Abstract

In a network comprising a provider edge router coupled to each of a mated pair of core routers in a core network, a system and methodology for rerouting upstream traffic destined for the provider edge router in the event of a link failure between one of the core routers and the provider edge router. By detecting a link failure between a first of the mated pair of core routers and the provider edge router, and directing the upstream traffic destined for the provider edge router to a second of the mated pair of core routers, internal gateway protocol (IGP) reconvergence events are not triggered.

Claims

1. In a network comprising a provider edge router coupled to each of a mated pair of core routers in a core network, a method for rerouting upstream traffic destined for the provider edge router in the event of a link failure between one of the core routers and the provider edge router, comprising the steps of:

detecting a link failure between a first of the mated pair of core routers and the provider edge router; and

directing the upstream traffic destined for the provider edge router to a second of the mated pair of core routers without triggering an internal gateway protocol (IGP) reconvergence event.

2. The method of claim 1, wherein the IGP is run exclusively on the core routers in the core network to disseminate routing information among the core routers, the IGP not running on the provider edge router.

3. The method of claim 1, wherein the provider edge router does not maintain a database of state information for the core routers in the core network.

4. A network in which traffic is routed from an ingress provider edge router to an egress provider edge router, the network eliminating the need to share state information between the ingress provider edge router and a plurality of core routers in a core network, the ingress provider edge router and egress provider edge router each coupled to first and second core routers forming a “

mated pair”

of core routers among the plurality of core routers in the core network, wherein;

the first core router of the mated pair coupled to the egress provider edge router is constructed and arranged for detecting a link failure between the first core router and the egress provider edge router;

the second core router of the mated pair coupled to the egress provider edge router is constructed and arranged for detecting a link failure between the second core router and the egress provider edge router; and

upon detection of a link failure between the first core router and the egress provider edge router, the first core router is adapted to send upstream traffic destined for the egress provider edge router to the second core router, and upon detection of a link failure between the second core router and the egress provider edge router, the second core router is adapted to send upstream traffic destined for the egress provider edge router to the first core router.

5. The network of claim 4, wherein the link failure does not trigger an internal gateway protocol (IGP) reconvergence event.

6. The network of claim 5, wherein the IGP is run exclusively on the core routers in the core network to disseminate routing information among the core routers, the IGP not running on the egress provider edge router.

7. The network of claim 4, wherein the provider edge routers do not maintain a database of state information for the core routers in the core network.