Cisco Systems Cisco Systems Cisco Systems Cisco Systems Cisco Systems Bell Canada Bell Canada CNIT Steinberg Consulting Segment Routing (SR) is applicable to both MPLS (SR-MPLS) and IPv6 (SRv6) data planes. This document specifies a procedure for using UDP path for sending and processing in-band Performance Measurement (PM) Probe query and response messages. The procedure uses RFC 6374 defined mechanisms for Delay and Loss performance measurement. The procedure defined is applicable to IPv4, IPv6, SR-MPLS and SRv6 data planes. This document also defines Return Path Segment List TLV for bidirectional performance measurement.