Huawei Technologies Huawei Technologies RtBrick Inc Etheric Networks HPE The Path Computation Element (PCE) is a core component of Software- Defined Networking (SDN) systems. A PCE-based Central Controller (PCECC) can simplify the processing of a distributed control plane by blending it with elements of SDN and without necessarily completely replacing it. Thus, the LSP can be calculated/set up/initiated and the label forwarding entries can also be downloaded through a centralized PCE server to each network device along the path while leveraging the existing PCE technologies as much as possible. This document specifies the procedures and PCEP extensions when a PCE-based controller is also responsible for configuring the forwarding actions on the routers, in addition to computing the paths for packet flows in a segment routing (SR) network and telling the edge routers what instructions to attach to packets as they enter the network. PCECC is further enhanced for SR-MPLS SID (Segment Identifier) allocation and distribution.