BGP LU resiliency using an anycast SID and BGP driven anycast path selection
A node, in a first network, includes circuitry configured to determine a next hop as decided by Border Gateway Protocol (BGP) is an anycast prefix to a Route Reflector (RR) interconnecting the first network with a second network, responsive to the next hop being the anycast prefix to the RR, create a tunnel with a destination based on the anycast prefix, and utilize the tunnel for traffic having the next hop as the anycast prefix to the RR. The anycast prefix is assigned to two or more RRs interconnecting the first network and the second network. A first path is decided by BGP based on a BGP Path Selection Algorithm that is independent of a second path determined by Interior Gateway Protocol (IGP). The first path and the second path can be different, and wherein tunnel is utilized to ensure the traffic always follows the first path.
1 . A node, in a first network, comprising circuitry configured to:
determine whether a next hop as decided by Border Gateway Protocol (BGP) utilizing a BGP Path Selection Algorithm is an anycast prefix to a Route Reflector (RR) interconnecting the first network with a second network;
responsive to the next hop being the anycast prefix to the RR, identify a non-anycast loopback IP address of the RR associated with the determined anycast prefix, and create a tunnel defining an on-demand tunnel path with a destination based on the anycast prefix, wherein the on-demand tunnel path is pinned to an upstream node directly connected to the RR via the identified non-anycast loopback IP address; and
utilize the tunnel for traffic having the next hop as the anycast prefix to the RR.
2 . The node of claim 1 , wherein the anycast prefix is assigned to two or more RRs interconnecting the first network and the second network, the RRs are configured to provide Label Switch Router (LSR) functionality.
3 . The node of claim 1 , wherein the BGP Path Selection Algorithm is configured to determine a primary path based on a plurality of parameters that is independent of a second path determined by Interior Gateway Protocol (IGP).
4 . The node of claim 3 , wherein the first path and the second path are different, and wherein the tunnel is utilized to ensure the traffic always follows the first path.
5 . The node of claim 3 , wherein the BGP Path Selection Algorithm utilizes a plurality of parameters where the IGP utilizes a shortest metric.
6 . The node of claim 1 , wherein the circuitry is further configured to responsive to the next hop not being the anycast prefix to the RR, send traffic to the next hop.
7 . A method, implemented in a node in a first network, comprising steps of:
determine whether a next hop as decided by Border Gateway Protocol (BGP) utilizing a BGP Path Selection Algorithm is an anycast prefix to a Route Reflector (RR) interconnecting the first network with a second network;
responsive to the next hop being the anycast prefix to the RR, identify a non-anycast loopback IP address of the RR associated with the determined anycast prefix, and create a tunnel defining an on-demand tunnel path with a destination based on the anycast prefix, wherein the on-demand tunnel path is pinned to an upstream node directly connected to the RR via the identified non-anycast loopback IP address; and
utilize the tunnel for traffic having the next hop as the anycast prefix to the RR.
8 . The method of claim 7 , wherein the anycast prefix is assigned to two or more RRs interconnecting the first network and the second network.
9 . The method of claim 7 , wherein a first path is decided by BGP based on a BGP Path Selection Algorithm that is independent of a second path determined by Interior Gateway Protocol (IGP).
10 . The method of claim 9 , wherein the first path and the second path are different, and wherein the tunnel is utilized to ensure the traffic always follows the first path.
11 . The method of claim 9 , wherein the BGP Path Selection Algorithm utilizes a plurality of parameters where the IGP utilizes a shortest metric.
12 . The method of claim 7 , wherein the steps further include responsive to the next hop not being the anycast prefix to the RR, send traffic to the next hop.
13 . A non-transitory computer-readable medium comprising instructions that, when executed, cause a node in a first network to:
determine whether a next hop as decided by Border Gateway Protocol (BGP) utilizing a BGP Path Selection Algorithm is an anycast prefix to a Route Reflector (RR) interconnecting the first network with a second network;
responsive to the next hop being the anycast prefix to the RR, identify a non-anycast loopback IP address of the RR associated with the determined anycast prefix, and create a tunnel defining an on-demand tunnel path with a destination based on the any cast prefix, wherein the on-demand tunnel path is pinned to an upstream node directly connected to the RR via the identified non-anycast loopback IP address; and
utilize the tunnel for traffic having the next hop as the anycast prefix to the RR.
14 . The non-transitory computer-readable medium of claim 13 , wherein the anycast prefix is assigned to two or more RRs interconnecting the first network and the second network.
15 . The non-transitory computer-readable medium of claim 13 , wherein a first path is decided by BGP based on a BGP Path Selection Algorithm that is independent of a second path determined by Interior Gateway Protocol (IGP).
16 . The non-transitory computer-readable medium of claim 15 , wherein the first path and the second path are different, and wherein the tunnel is utilized to ensure the traffic always follows the first path.
17 . The non-transitory computer-readable medium of claim 15 , wherein the BGP Path Selection Algorithm utilizes a plurality of parameters where the IGP utilizes a shortest metric.