G.709

ITU-T Recommendation G.709 "Interfaces for the Optical Transport Network (OTN)" describes a means of communicating data over an optical network. 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.

The G.709 OTUk signal is positioned as a server layer signal for various client signals, e.g. SDH/SONET, ATM, , Ethernet, Fibre Channel and OTN ODUk (where k=0, 1, 2, 2e, 3, 3e2, 4 or flex). Work on support for InfiniBand and Common Public Radio Interface client signals is currently in progress.

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).

Unlike SDH/SONET, the line rate is increased by maintaining the G.709 frame structure (4 rows x 4080 columns) and decreasing the frame period (in SDH/SONET the frame structure is increased and the frame period of 125 µs is maintained).

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