What are other processes that MPLS/IP routers can do with, or to MPLS label stack?
1 Answer
MPLS label is erased from the top of the label stack upon MPLS tunnel termination.
Sometimes, to save an additional MPLS table lookup on PE routers, a PHP(Penultimate Hop Popping) mechanism is employed - which pops the MPLS tunnel label one hop earlier (in P router). This is done by a special "label 3" signal from the PE router towards the neighboring P router.
