The optical transport network (OTN) supports the operation and management aspects of optical networks of various architectures, e.g., point-to-point, ring and mesh architectures.

This Recommendation defines the interfaces of the OTN to be used within and between subnetworks of the optical network, in terms of:

– OTN hierarchy;

– functionality of the overhead in support of multi-wavelength optical networks;

– frame structures;

– bit rates;

– formats for mapping client signals.

Functions and process flows associated with the defined interfaces are specified in [ITU-T G.798].

The interfaces defined in this Recommendation can be applied at user-to-network interfaces (UNI) and network node interfaces (NNI) of the OTN.