RSVP IGP synchronization for remote links

RSVP IGP Synchronization for remote links enables an LSP ingress router to react to neighbor down events from any location in the network. Any non-FRR can be rerouted when the router receives an IGP link or neighbor down event.

MPLS builds an IGP Sync database which is independent of the MPLS-TE database. The IGP Sync database links are keyed based on IPv4 address pair (Link IP, Router-ID of Links remote end). The link is added or updated in the database whenever an LSP Path comes UP. The IGP Link is deleted or updated whenever an LSP path goes DOWN or an IGP link down event gets generated. The IGP Link database links are associated with individual LSP instances, such that when an IGP link down event reaches MPLS, MPLS can correlate it to individual LSP paths.

An RSVP IGP synchronization remote link down event can lead to any one of the below actions:

• Bring down an LSP and retry it (setup on new path avoiding failed link) OR
• Bring down an LSP and switch to any other instance (secondary path) which is already up OR
• Create a new instance of the LSP first and then switch to the new instance.

Limitations and pre-requisites

• RSVP IGP synchronization for remote links is not usable when Traffic Engineering is not enabled in any of the routers used by the LSP.
• No additional or separate configurations are required to enable or disable.
• For full functionality of RSVP IGP synchronization for remote links, it is recommended that:
  • All routers used by all the non-FRR must be Traffic Engineering enabled.
  • All transit routers shall support RRO.