This document specifies the mapping and notification of defect states
between a pseudowire (PW) and the Attachment Circuits (ACs) of the
end-to-end emulated service. It standardizes the behavior of
Provider Edges (PEs) with respect to PW and AC defects. It addresses
ATM, Frame Relay, Time Division Multiplexing (TDM), and Synchronous
Optical Network / Synchronous Digital Hierarchy (SONET/SDH) PW
services, carried over MPLS, MPLS/IP, and Layer 2 Tunneling Protocol
version 3/IP (L2TPv3/IP) Packet Switched Networks (PSNs). [STANDARDS-TRACK]