Cisco Systems, Inc. Cisco Systems, Inc. Verizon Wireless ZTE Corp. This document describes the procedure for encapsulating the Simple Two-Way Active Measurement Protocol (STAMP), defined in RFC 8762, and its optional extensions defined in RFC 8972, in MPLS networks. Label Switched Paths (LSPs) and Pseudowires (PWs) are used in MPLS networks for various services, including Layer 2 and Layer 3 data packets, and may use the Control Word (CW). The procedure for encapsulating STAMP test packets with or without the CW and/or an IP/UDP header for LSPs and PWs is also described. This document updates RFC 8972: STAMP Test Session Identifier.