ITU-T Recommendation G.709 Interfaces for the Optical Transport Network (OTN) describes a means of communicating data over an optical network.
[1] It is a standardized method for transparent transport of services over optical wavelengths in DWDM systems.
It is also known as Optical Transport Hierarchy (OTH) standard.
[3] Work on support for InfiniBand and Common Public Radio Interface client signals is currently[when?]
The frame structure defined in G.709 is constructed of 4 areas: G.709 offers advanced OAM&P capabilities such as Tandem Connection Monitoring (TCM), End to End performance monitoring, connectivity monitoring, signal quality supervision and General Communication Channel (GCC).