Cisco Systems, Inc. Cisco Systems, Inc. Verizon Wireless ZTE Corp. This document specifies encapsulations for the Simple Two-Way Active Measurement Protocol (STAMP), defined in RFC 8762, and its optional extensions, defined in RFC 8972, in MPLS networks. It specifies the encapsulation of STAMP test packets for point-to-point Label Switched Paths (LSPs) and point-to-point single-segment Pseudowires (PWs), with or without an IP/UDP header, so that the test packets experience the same forwarding and Equal-Cost Multi-Path (ECMP) behavior as the data traffic being measured. In addition, two new MPLS Generic Associated Channel (G-ACh) types are defined. This document updates RFC 8762 for TTL and IPv6 Hop Limit processing and RFC 8972 for the STAMP Session Identifier for LSPs and PWs.