From Part II of RSVP Reservation Protocol CPS640 Internet and Multimedia Technologies -- Spring 98. byMarek Podgorny,Nancy McCracken
Two types of RSVP teardown message:
PathTear message travels towards all receivers downstream from its point of initiation and deletes path state, as well as all dependent reservation state, along the way.
ResvTear message deletes reservation state and travels towards all senders upstream from its point of initiation.
A teardown request may be initiated either by sender or receiver, or by a router as the result of state timeout.
State change will be propagated immediately to the next node, but only if there will be a net change after merging. As a result, an ResvTear message will prune the reservation state back (only) as far as possible.
