This document describes alternate mechanisms to perform some of the
functions of MPLS Transport Profile (MPLS-TP) linear protection
defined in RFC 6378, and also defines additional mechanisms. The
purpose of these alternate and additional mechanisms is to provide
operator control and experience that more closely models the behavior
of linear protection seen in other transport networks. This document
also introduces capabilities and modes for linear protection. A
capability is an individual behavior, and a mode is a particular
combination of capabilities. Two modes are defined in this document:
Protection State Coordination (PSC) mode and Automatic Protection
Switching (APS) mode. This document describes the behavior of the PSC
protocol including priority logic and state machine when all the
capabilities associated with the APS mode are enabled. This document
updates RFC 6378 in that the capability advertisement method defined
here is an addition to that document.