This memo explains the motivation and describes the reassignment of well-known ports for the One-Way Active Measurement Protocol (OWAMP) and the Two-Way Active Measurement Protocol (TWAMP) for control and measurement. It also clarifies the meaning and composition of these Standards Track protocol names for the industry. This memo updates RFCs 4656 and 5357@ in terms of the UDP well-known port assignments@ and it clarifies the complete OWAMP and TWAMP protocol composition for the industry.