Recommendation ITU-T G.8013/Y.1731 provides mechanisms for user-plane OAM functionality in Ethernet networks according to the requirements and principles given in Recommendation ITU‑T Y.1730. This Recommendation is designed specifically to support point-to-point connections and multipoint connectivity in the ETH layer as identified in Recommendation ITU‑T G.8010/Y.1306. The OAM mechanisms defined in this Recommendation offer capabilities to operate and maintain network and service aspects of the ETH layer. Corrigendum 1 corrects the description of the Length field in the Test ID TLV of the 1DM PDU in clause 9.14.2.