What is the purpose of RSVP tear messages?

RSVP tear messages primarily remove an LSP reservation; informing the headend of LSP issues is a consequence or a trigger for tearing down, not the primary purpose of the tear message itself.

Successful end-to-end resource allocation is confirmed by the reception of RSVP Resv messages at the headend router, not by tear messages.

RSVP tear messages are sent by a router to explicitly remove a resource reservation that was previously established for a particular flow or LSP. This action frees up the allocated bandwidth and other resources on all routers along the path, allowing them to be utilized by other reservation requests.

While a tear message might follow an unavailability event, its direct purpose is to cancel an existing reservation, not to notify of unavailability in general on a transit router.