Automatic prioritization of BGP next-hop in IGP convergence

1. A method comprising:

storing, by an inter-domain routing protocol, an inter-domain routing protocol route having an associated next-hop address;

searching a routing table for an intra-domain routing protocol route used to reach the next-hop address of the inter-domain routing protocol route, wherein whether or not a route is used to reach the next-hop address of an inter-domain routing protocol route indicates whether or not the route should be marked as an important route for convergence;

in response to locating an intra-domain routing protocol route being used to reach the next-hop address of the inter-domain routing protocol route, marking the intra-domain routing protocol route as an important route for convergence; and

in response to a change in a network requiring a routing table update, processing the intra-domain routing protocol route marked as an important route for convergence, by an intra domain routing protocol, before processing any other intra-domain routing protocol routes that are not marked as important routes for convergence.

2. The method of claim 1 wherein the inter-domain routing protocol is a Border Gateway Protocol (BGP) and wherein the inter-domain routing protocol route is a BGP route.

3. The method of claim 1 wherein the intra-domain routing protocol is an interior gateway protocol (IGP) and wherein the intra-domain routing protocol route is an IGP route.

4. The method of claim 3 wherein the IGP is one of Open Shortest Path First (OSPF) and Intermediate-System-to-Intermediate-System (ISIS) protocol.

5. The method of claim 1 further comprising:

storing the intra-domain routing protocol route marked as an important route for convergence in a list of routes maintained by the intra-domain routing protocol.

6. The method of claim 1 further comprising

managing the routing table with a routing information base (RIB); and

wherein the step of searching is implemented by the RIB.

7. The method of claim 1 wherein the steps of storing, searching, and processing are implemented internal to a router.

8. The method of claim 1 wherein the marking comprises asserting a flag associated with a routing table entry corresponding to the route.

9. An apparatus comprising:

a route processor;

an inter-domain routing protocol that when executed by the route processor stores an inter-domain routing protocol route that has an associated next-hop address in a routing table within the apparatus;

a routing information base (RIB) that when executed by the route processor manages the routing table, the RIB configured to search the routing table for an intra-domain routing protocol route used to reach the next-hop address of the inter-domain routing protocol route, wherein whether or not a route is used to reach the next-hop address of an inter-domain routing protocol route indicates whether or not the route should be marked as an important route for convergence, and in response to locating an intra-domain routing protocol locating such route being used to reach the next-hop address of the inter-domain routing protocol route, mark the located intra-domain routing protocol route as an important route for convergence; and

an intra-domain routing protocol that when executed by the route processor interacts with the RIB, the intra-domain routing protocol configured to, in response to a change in a network requiring a routing table update, process the intra-domain routing protocol route marked as an important route for convergence before any other intra-domain routing protocol routes that are not marked as important routes for convergence.

10. The apparatus of claim 9 wherein the inter-domain routing protocol is a Border Gateway Protocol (BGP) and wherein the inter-domain routing protocol route is a BGP route.

11. The apparatus of claim 10 wherein the intra-domain routing protocol is an interior gateway protocol (IGP) and wherein the intra-domain routing protocol route is an IGP route.

12. The apparatus of claim 11 wherein the IGP is one of Open Shortest Path First (OSPF) and Intermediate-System-to-Intermediate-System (ISIS) protocol.

13. The apparatus of claim 11 wherein the intra-domain routing protocol is further configured to store the intra-domain routing protocol route marked as an important route for convergence in a list of routes maintained by the intra-domain routing protocol.

14. The apparatus of claim 11 wherein the apparatus is a router.

15. The apparatus of claim 11 wherein the RIB is configured to mark the route as an important route for convergence with a flag in a routing table entry corresponding to the route.

16. An apparatus comprising:

means for storing an inter-domain routing protocol route having an associated next-hop address within the apparatus;

means for searching a routing table for an intra-domain routing protocol route used to reach the next-hop address of the inter-domain routing protocol route, wherein whether or not a route is used to reach the next-hop address of an inter-domain routing protocol route indicates whether or not the route should be marked as an important route for convergence;

means for, in response to locating an intra-domain routing protocol route being used to reach the next-hop address of the inter-domain routing protocol route, marking the located intra-domain routing protocol route as an important route for convergence; and

means for processing, in response to a change in a network requiring a routing table update, the intra-domain routing protocol route marked as an important route for convergence before processing any other intra-domain routing protocol routes that are not marked as important routes for convergence.

17. The apparatus of claim 16 wherein the inter-domain routing protocol is a Border Gateway Protocol (BGP) and wherein the inter-domain routing protocol route is a BGP route.

18. The apparatus of claim 16 wherein the intra-domain routing protocol is an interior gateway protocol (IGP) and wherein the intra-domain routing protocol route is an IGP route.

19. The apparatus of claim 18 wherein the IGP is one of Open Shortest Path First (OSPF) and Intermediate-System-to-Intermediate-System (ISIS) protocol.

20. The apparatus of claim 16 wherein the apparatus is a router.

21. A method comprising:

storing, by an inter-domain routing protocol, an inter-domain routing protocol route having an associated next-hop address;

searching a routing table for an intra-domain routing protocol route used to reach the next-hop address of the inter-domain routing protocol route, and considering such route as an important route for convergence;

storing the intra-domain routing protocol route considered as an important route for convergence in a list of routes maintained by the intra-domain routing protocol; and

in response to a change in a network requiring a routing table update, processing the intra-domain routing protocol route considered as an important route for convergence, by an intra domain routing protocol, before processing any other intra-domain routing protocol routes that are not considered as important routes for convergence.

22. The method of claim 21 wherein the inter-domain routing protocol is a Border Gateway Protocol (BGP) and wherein the inter-domain routing protocol route is a BGP route.

23. The method of claim 21 wherein the intra-domain routing protocol is an interior gateway protocol (IGP) and wherein the intra-domain routing protocol route is an IGP route.

24. The method of claim 21 wherein the considering as an important route for convergence comprises marking a routing table entry corresponding to the route with a flag.

25. The method of claim 21 wherein the steps of storing, searching, and processing are implemented internal to a router.