A local backup for a signaled LSP
An RSVP-TE head-end establishes a primary label-switched path (LSP). Fast reroute (FRR) can prepare a backup before failure. A router immediately upstream of the protected resource is the point of local repair (PLR). It can divert traffic onto a backup LSP and rejoin the primary path at a downstream merge point.
One-to-one protection builds a detour for an individual protected LSP at a repair point. Facility backup can use one bypass tunnel to protect multiple LSPs that cross the same resource.
Link protection and node protection
A next-hop bypass can avoid a failed link and rejoin at the next router. A next-next-hop bypass can avoid the next router itself and rejoin farther downstream. Link protection alone can still depend on the router at the other end of the failed link.
This is a local repair for protected RSVP-TE LSPs. The head-end can later signal a new end-to-end path. TI-LFA instead computes a segment list for local repair of SR and IGP forwarding.
Try it in a lab
- On RSVP-TE-capable lab routers, signal a primary tunnel and provision local protection. Confirm the point of local repair, protected resource and downstream merge point before failure.
- Send traffic through the primary tunnel and disconnect the protected link in the lab. Observe that the PLR uses the backup while the tunnel’s original resource is unavailable.
- Compare link and node protection by checking whether each backup still traverses the primary next-hop router.