This reports an optional alternate EtherType used specifically for ITU-T Y.1731 frames, separate from the primary CFM EtherType, since some deployments or legacy equipment expect Y.1731 performance-monitoring frames (like DMM/LMM/SLM) to be tagged distinctly from basic 802.1ag continuity-check frames. An admin needs both EtherTypes configured consistently across a maintenance domain, since a mismatch here specifically would break Y.1731 delay/loss measurement (DMM, LMM) exchanges even while basic CCM continuity checking using the primary EtherType keeps working fine. For example, if a neighboring device only recognizes the default Y.1731 EtherType 0x8902 shared with CFM and cienaCesCfmY1731EtherType has been set to a nonstandard value, delay-measurement tests would fail to get a response even though the link's basic continuity checks stay up.