Ciena Corporation Ciena Corporation Cisco Systems, Inc. Juniper Networks, Inc. Huawei Technologies Nokia A Segment Routing (SR) Policy is an ordered list of instructions, called "segments" that represent a source-routed policy. Packet flows are steered into an SR Policy on a node where it is instantiated. An SR Policy is made of one or more candidate paths. This document specifies the Path Computation Element Communication Protocol (PCEP) extension to signal candidate paths of an SR Policy. Additionally, this document updates RFC 8231 to allow delegation and setup of an SR Label Switched Path (LSP), without using the path computation request and reply messages. This document is applicable to both Segment Routing over MPLS (SR-MPLS) and Segment Routing over IPv6 (SRv6).