Recommendation ITU-T G.8051/Y.1345 addresses management aspects of the Ethernet transport network element containing transport functions of one or more of the layer networks of the Ethernet transport network. The management of the Ethernet layer networks is separable from that of its client layer networks so that the same means of management can be used regardless of the client. Themanagement functions for fault management, configuration management, performance monitoring, and security management are specified.The 2009 revision of this Recommendation added the management of additional transport functions that were introduced in the 2009 revision of Recommendation ITU-T G.8021/Y.1341. The 2013 revision of this Recommendation added the management of additional functions, including: client signal fail (CSF); proactive loss measurement using loss measurement message (LMM)/loss measurement reply (LMR); proactive delay measurement using delay measurement message (DMM)/delay measurement reply (DMR) and one-way delay measurement (1DM); synthetic loss measurement using synthetic loss message (SLM)/synthetic loss reply (SLR) and one-way syntheticloss measurement (1SL) (proactive and on-demand); performance management (PM) requirements on protocol data unit (PDU) generation type, message period, measurement interval, repetition period, start time, stop time and session duration; and PM data collection requirements. The 2015 Revision of this Recommendation has updated the management information (MI) signals for the ETHx_FT function in clause 8.5, the MI signals for the ETHx/MCC function in clause 8.6, the one-way synthetic loss measurement (1SL) MI signal for the ETHDe_FT_Sk function in clause 8.8, and the on-demand and proactive loss measurement requirements in clause 10.2.