Cisco Systems, Inc. Juniper Networks Comcast The Path Computation Element Communication Protocol (PCEP) provides mechanisms for Path Computation Elements (PCEs) to perform path computations in response to Path Computation Clients (PCCs) requests. The Stateful PCE extensions allow stateful control of Multiprotocol Label Switching (MPLS) Traffic Engineering (TE) Label Switched Paths (LSPs) using PCEP. This document defines PCEP extensions for grouping two unidirectional MPLS TE LSPs (one in each direction in the network) into an Associated Bidirectional LSP. The mechanisms defined in this document can be applied using a Stateful PCE for both PCE-Initiated and PCC-Initiated LSPs, as well as when using a Stateless PCE. The procedures defined are applicable to the LSPs using Resource Reservation Protocol (RSVP) for signaling.