The PCE Working Group is chartered to specify the required protocols so as to enable a Path Computation Element (PCE)-based architecture for the computation of paths for MPLS and GMPLS Point to Point and Point to Multi-point Traffic Engineered LSPs. In this architecture path computation does not necessarily occur on the head-end (ingress) LSR, but on some other path computation entity that may physically not be located on each head-end LSR. The PCE WG works on application of this model within a single domain or within a group of domains (where a domain is a layer, IGP area or Autonomous System with limited visibility from the head-end LSR). At this time, applying this model to large groups of domains such as the Internet is not thought to be possible, and the PCE WG will not spend energy on that topic. The WG specifies the PCE communication Protocol (PCEP) and needed extensions for communication between LSRs (termed Path Computation Clients - PCCs) and PCEs, and between cooperating PCEs. Security mechanisms such as authentication and confidentiality are included. The WG determines requirements for extensions to existing routing and signaling protocols in support of the PCE architecture and the signaling of inter-domain paths (e.g. RSVP-TE and its GMPLS variations). Any necessary extensions will be produced in collaboration with the Working Groups responsible for the protocols. The WG also works on the mechanisms to for multi-layer path computation and PCEP extensions for communication between several network layers. The WG defines the required PCEP extensions for Wavelength Switched Optical Networks (WSON) while keeping consistency with the GMPLS architecture specified in the CCAMP WG. Work Items: - PCEP extensions for MPLS and GMPLS Traffic Engineered LSP path computation models involving PCE(s). This includes the case of computing the paths of intra and inter-domain TE LSPs. Such path computation includes the generation of primary, protection and recovery paths, as well as computations for (local/global) reoptimization and load balancing. Both intra- and inter-domain applications are covered. - In cooperation with protocol specific Working Group (e.g., MPLS, CCAMP), development of LSP signaling (RSVP-TE) extensions required to support PCE-based path computation models. - Specification of PCEP extensions for communication in the various GMPLS-controlled networks, including WSON. - Definition of PCEP extensions for path computation in multi-layer networks. - Definition of the PCEP extensions used by a stateful PCE for recommending a new path for an existing or new LSP to the PCC/PCE. Further protocol extensions must cover the case where the recommendation is not followed by the PCC/PCE.