Cisco Systems, Inc. Cisco Systems, Inc. ZTE Corporation Huawei Technologies Nokia The SR-Algorithm associated with a Segment-ID (SID) defines the path computation algorithm used by Interior Gateway Protocols (IGPs). This information is available to controllers, such as the Path Computation Element (PCE), via topology learning. This document proposes an approach for informing headend routers regarding the SR- Algorithm associated with each SID used in PCE-computed paths, as well as signaling a specific SR-Algorithm as a constraint to the PCE.