Recommendation ITU-T G.8262/Y.1362 outlines requirements for timing devices used in synchronizing network equipment that uses synchronous Ethernet. This Recommendation defines the requirements for clocks, e.g., bandwidth, frequency accuracy, holdover and noise generation.
ITU-T G.8262-2010 history
2010ITU-T G.8262-2010 Timing characteristics of a synchronous Ethernet equipment slave clock Study Group 15