ODU3

ODU3 stands for Optical Data Unit level 3, a container defined in the ITU-T Optical Transport Network (OTN) architecture. It is designed to carry client data streams at roughly 40 Gbit/s and to be multiplexed with other ODUs and with higher-rate Optical Transport Units (OTUs) for scalable capacity.

ODU3 is part of the ODU hierarchy, which includes ODU0 through ODU4. It corresponds to the odor associated with OTU3, the 40 Gbit/s optical line rate. The ODU3 frame provides a payload of up to about 40 Gbit/s and includes overhead used for framing, synchronization, and management.

The structure of an ODU3 frame comprises a payload unit and overhead that support path management, performance monitoring, and error handling. It enables mapping and grooming of a variety of client signals, such as Ethernet, Fibre Channel, and SDH/SONET payloads, for transport over an Optical Channel in an OTN. The standard also supports flexible rate adaptation through concepts like ODUflex for variable bandwidth services.

In practical use, ODU3 is employed in high-capacity backbone, metro, and long-haul networks to transport aggregated client signals over wavelength-division multiplexing (WDM) systems. It is part of the ITU-T G.709 family of standards and is linked to the evolved OTU3/OTU4 hierarchy, enabling scalable, resilient optical transport.