Cisco Systems Cisco Systems Bell Canada Google, Inc. Microsoft Segment Routing (SR) allows a headend node to steer a packet flow along any path. Intermediate per-flow states are eliminated thanks to source routing. The headend node steers a flow into an SR Policy. The header of a packet steered in an SR Policy is augmented with an ordered list of segments associated with that SR Policy. This document details the concepts of SR Policy and steering into an SR Policy.