Anycast-based internet protocol redirection to alleviate partial routing tables
View Patent ↗Systems and methods are described that instruct routers having constrained hardware/memory to redirect all outbound traffic to a helper router. The helper router contains a full routing table that can forward any packet to its destination. In a large service provider network, helper routers may be distributed at multiple locations across the network. Since packets must detour through the helper router, the distributed helper routers minimize latency.
1. A method for configuring a data communications network, the data communications network including a plurality of interconnected routers with one or more helper routers and one or more non-helper routers, each helper router having a full routing table, the method comprising:
by a non-helper router, receiving an announcement of a default route of a helper router via anycast-prefix addressing over a routing protocol;
by the non-helper router, receiving instructions to delete a full routing table of the non-helper router, the instructions being based on a determination that the non-helper router is a constrained router; and
by the non-helper router, in response to the instructions to delete the full routing, deleting the full routing table of the non-helper router.
2. The method according to claim 1 , wherein the determination that the non-helper router is a constrained router is based upon router memory and network routing table size.
3. The method according to claim 1 , further comprising:
by the non-helper router, after deleting the routing table, forwarding received packets having a destination address to the closest helper router where a next hop look-up for that destination is performed.
4. The method according to claim 3 , further comprising:
by the non-helper router, prioritizing each helper router's location in the network.
5. The method according to claim 3 , further comprising:
by the non-helper router, receiving an anycast-prefix from each helper router wherein a static default route points to the anycast-prefix.
6. The method according to claim 3 , further comprising:
by the helper router, forwarding a received packet to an optimal next hop.
7. The method according to claim 1 wherein the one or more helper routers are distributed throughout the network.
8. The method according to claim 1 wherein the routing protocol is comprised of at least one of Border Gateway Protocol (BGP), Open Shortest Path First (OSPF), Intermediate System to Intermediate System (IS IS), Routing Information Protocol (RIP) and Interior Gateway Routing Protocol (IGRP).
9. The method according to claim 1 , wherein the data communications network further includes a route reflector, the method further comprising:
by the route reflector, selecting a closest router having a full routing table for the non-helper router.
10. The method according to claim 9 wherein selecting a closest router is based on a lowest helper router routing metric.
11. A non-transitory computer-readable medium having stored thereon computer readable instructions for configuring a data communications network, the data communications network including a plurality of interconnected routers with one or more helper routers and one or more non-helper routers, each helper router having a full routing table, wherein execution of the computer readable instructions by a processor causes the processor to perform operations comprising:
by a non-helper router, receiving an announcement of a default route of a helper router via anycast-prefix addressing over a routing protocol;
by the non-helper router, receiving instructions to delete a full routing table of the non-helper router, the instructions being based on a determination that the non-helper router is a constrained router; and
by the non-helper router, in response to the instructions to delete the full routing, deleting the full routing table of the non-helper router.
12. The non-transitory computer-readable medium according to claim 11 , wherein the determination that the non-helper router is a constrained router is based upon router memory and network routing table size.
13. The non-transitory computer-readable medium according to claim 11 , wherein the operations further comprise:
by the non-helper router, after deleting the routing table, forwarding received packets having a destination address to the closest helper router where a next hop look-up for that destination is performed.
14. The non-transitory computer-readable medium according to claim 13 , wherein the operations further comprise:
by the non-helper router, prioritizing each helper router's location in the network.
15. The non-transitory computer-readable medium according to claim 13 , wherein the operations further comprise:
by the non-helper router, receiving an anycast-prefix from each helper router wherein a static default route points to the anycast-prefix.
16. The non-transitory computer-readable medium according to claim 13 , wherein the operations further comprise:
by the helper router, forwarding a received packet to an optimal next hop.
17. The non-transitory computer-readable medium according to claim 11 wherein the one or more helper routers are distributed throughout the network.
18. The non-transitory computer-readable medium according to claim 11 wherein the routing protocol is comprised of at least one of Border Gateway Protocol (BGP), Open Shortest Path First (OSPF), Intermediate System to Intermediate System (IS IS), Routing Information Protocol (RIP) and Interior Gateway Routing Protocol (IGRP).
19. The non-transitory computer-readable medium according to claim 11 , wherein the data communications network further includes a route reflector, and wherein the operations further comprise:
by the route reflector, selecting a closest router having a full routing table for the non-helper router.
20. The non-transitory computer-readable medium according to claim 19 wherein selecting a closest router is based on a lowest helper router routing metric.