Cisco Systems, Inc. Cisco Systems, Inc. ZTE Corporation Huawei Technologies Nokia This document specifies extensions to the Path Computation Element Communication Protocol (PCEP) to enhance support for Segment Routing (SR) with a focus on the use of Segment Identifiers (SIDs) and SR- Algorithms in Traffic Engineering (TE). The SR-Algorithm associated with a SID defines the path computation algorithm used by Interior Gateway Protocols (IGPs). It introduces mechanisms for PCEP peers to signal SR-Algorithm associated with SIDs by encoding this information in Explicit Route Object (ERO) and Record Route Object (RRO) subobjects, enables SR-Algorithm constraints for path computation, and defines new metric types for the METRIC object. This document updates RFC 8664 and RFC 9603 to allow such extensions.