Recommendation ITU-T G.988 specifies the optical network unit (ONU) management and control interface (OMCI) for optical access networks.

First, it specifies the managed entities of a protocol-independent management information base (MIB) that models the exchange of information between an optical line termination (OLT) and an optical network unit (ONU). In addition, it covers the ONU management and control channel, protocol and detailed messages.