Handling diversity constraints with segment routing and centralized PCE

1 . A non-transitory computer-readable medium having instructions stored thereon for programming one or more processors to perform steps of:

computing a path for a service in a Segment Routing network where the path includes an explicit list of routers and interfaces in the Segment Routing network, wherein the explicit list of routers specifies every router along the path and the interfaces are on individual routers;

determining a Segment Identifier (SID) list for the path; and

signaling both the explicit list of routers and interfaces and the SID list to a head-end router for the service, such that the head-end router ensures the service is on the explicit list of routers and interfaces despite any deviations due to on-router computation using a comparison of the SID list and the explicit list at the head-end router.

2 . The non-transitory computer-readable medium of claim 1 , wherein the SID list is compressed where it does not include a SID for each of the routers in the explicit list of routers.

3 . The non-transitory computer-readable medium of claim 1 , wherein the steps further include

monitoring Traffic Engineering characteristics in the Segment Routing network based on knowing the service is on the explicit list of routers.

4 . The non-transitory computer-readable medium of claim 1 , wherein the steps further include

computing one or more backup paths for the service each with a corresponding explicit list of routers;

determining a SID list for the one or more backup paths; and

signaling the SID list for the one or more backup paths and the corresponding explicit list of routers to the head-end router.

5 . The non-transitory computer-readable medium of claim 4 , wherein the steps further include

monitoring Traffic Engineering characteristics in the Segment Routing network based on knowing the service is on one of the explicit list of routers and the corresponding explicit list of routers for the one or more backup paths.

6 . The non-transitory computer-readable medium of claim 1 , wherein the steps further include

participating in one or more routing protocols associated with the Segment Routing network.

7 . The non-transitory computer-readable medium of claim 6 , wherein the steps further include

performing the computing in a same manner as routers in the Segment Routing network.

8 . The non-transitory computer-readable medium of claim 1 , wherein the one or more processors are associated with one of a Path Computation Element (PCE) and a Software Defined Networking (SDN) controller.

9 . A method comprising steps of:

computing a path for a service in a Segment Routing network where the path includes an explicit list of routers and interfaces in the Segment Routing network, wherein the explicit list of routers specifies every router along the path and the interfaces are on individual routers;

determining a Segment Identifier (SID) list for the path; and

signaling both the explicit list of routers and interfaces and the SID list to a head-end router for the service, such that the head-end router ensures the service is on the explicit list of routers and interfaces despite any deviations due to on-router computation using a comparison of the SID list and the explicit list at the head-end router.

10 . The method of claim 9 , wherein the SID list is compressed where it does not include a SID for each of the routers in the explicit list of routers.

11 . The method of claim 9 , wherein the steps further include

monitoring Traffic Engineering characteristics in the Segment Routing network based on knowing the service is on the explicit list of routers.

12 . The method of claim 9 , wherein the steps further include

computing one or more backup paths for the service each with a corresponding explicit list of routers;

determining a SID list for the one or more backup paths; and

signaling the SID list for the one or more backup paths and the corresponding explicit list of routers to the head-end router.

13 . The method of claim 12 , wherein the steps further include

monitoring Traffic Engineering characteristics in the Segment Routing network based on knowing the service is one of the explicit list of routers and the corresponding explicit list of routers for the one or more backup paths.

14 . The method of claim 9 , wherein the steps further include

participating in one or more routing protocols associated with the Segment Routing network.

15 . The method of claim 14 , wherein the steps further include

performing the computing in a same manner as routers in the Segment Routing network.

16 . The method of claim 14 , wherein the method is performed by one of a Path Computation Element (PCE) and a Software Defined Networking (SDN) controller.

17 . An apparatus comprising:

one or more processors and memory storing instructions that, when executed, cause the one or more processors to

compute a path for a service in a Segment Routing network where the path includes an explicit list of routers and interfaces in the Segment Routing network, wherein the explicit list of routers specifies every router along the path and the interfaces are on individual routers,

determine a Segment Identifier (SID) list for the path, and

signal both the explicit list of routers and interfaces and the SID list to a head-end router for the service, such that the head-end router ensures the service is on the explicit list of routers and interfaces despite any deviations due to on-router computation using a comparison of the SID list and the explicit list at the head-end router.

18 . The apparatus of claim 17 , wherein the SID list is compressed where it does not include a SID for each of the routers in the explicit list of routers.

19 . The apparatus of claim 17 , wherein the memory storing instructions that, when executed, further cause the one or more processors to

monitor Traffic Engineering characteristics in the Segment Routing network based on knowing the service is on the explicit list of routers.

20 . The apparatus of claim 17 , wherein the apparatus is one of a Path Computation Element (PCE) and a Software Defined Networking (SDN) controller.