Like WANs, a MAN is made up of interconnected LANs. Because MANs are smaller, they are usually more efficient than WANs, since data does not have to travel over large distances. MANs typically combine the networks of multiple organizations, instead of being managed by a single organization.
Most MANs use fiber optic cables to form connections between LANs. Often a MAN will run on "dark fiber" — formerly unused fiber optic cables that are able to carry traffic. These fiber optic cables may be leased from private-sector Internet service providers (ISP).
In some cases, this model is reversed: a city government builds and maintains a metropolitan fiber optic network, then leases dark fiber to private companies.
