The meaning of metropolitan area network originally comes from computer network. The ITU-T has so far not specifically indicated in the proposal the definition of the metropolitan Area Network in the telecommunication network.
At present, the operators began to build the metropolitan area network and different from the usual meaning of the metropolitan area network. For example, the metropolitan area network defined by China Mobile means: The network covering the city and its suburbs and providing a comprehensive transport platform for the metropolitan areas is mainly used in large and medium-sized cities.
The metropolitan area network is based on the multi service Optical transmission network, realizes the voice, data, image, multimedia, IP and so on, and mainly refers to the complete agreement interworking between the enterprise and individual users in the access network and the operators on the backbone networks.
The main technologies used in metropolitan area network transmission are MSTP based on SDH, OADM based on DWDM, and optical fiber direct connection technology.