Siemens AG This document specifies the particular requirements for edge-to-edge-emulation of circuits carrying time division multiplexed digital signals of the PDH as well as the SONET/SDH hierarchy over packet-switched networks. It is based on the common architecture for Pseudo Wire Emulation Edge-to-Edge (PWE3) as defined in [PWE3-ARCH]. It makes references to requirements in [PWE3-REQ] where applicable and complements [PWE3-REQ] by defining requirements originating from specifics of TDM circuits.