Overview

A metropolitan area network (MAN) is a communications network designed to interconnect several local area networks (LANs) within a geographic area larger than a single site but smaller than a wide area network (WAN), typically spanning a city, suburb, or large campus. A MAN aggregates traffic from multiple LANs to provide high‑capacity links for data, voice and video services. In concept it sits between the private networks of individual buildings and the provider networks that connect across regions.

Characteristics and architecture

MANs generally emphasize high bandwidth and relatively low latency over distances commonly up to several tens of kilometres; some definitions extend to about 100 km for dispersed urban installations. Common physical mediums include fiber‑optic cable, point‑to‑point microwave, and sometimes leased copper circuits. Architectures vary from ring and mesh topologies to switched fabrics arranged by service providers.

  • Typical components: aggregation switches, optical transport, metropolitan routers and customer edge devices.
  • Common technologies: metro Ethernet, SONET/SDH, MPLS and historically protocols such as Asynchronous Transfer Mode (ATM), SMDS and DQDB.
  • Service models: carrier‑operated MANs, consortium or municipal networks, and campus MANs operated by institutions.

History and development

MANs emerged in the late 1980s and 1990s as cities and large organizations required higher capacity than LANs could provide and a more localized solution than national WANs. Early implementations relied on technologies developed for telecoms, such as SONET and ATM. Over time, Ethernet scaled up to metro deployments (often called metro Ethernet), simplifying management and reducing cost while increasing throughput to gigabit and multiservice levels.

Uses, examples and importance

Metropolitan networks are used to link institutional campuses, business districts, data centers and public services within a city. For example, a university may connect multiple buildings and research labs across a campus via a MAN; see the notion of a campus and university deployments. MANs support shared Internet access, centralized storage, city‑wide surveillance, and disaster recovery between sites.

Distinctions and notable facts

MANs differ from a simple local area network (LAN) in scale and from a WAN in scope and management: a MAN typically covers a single metropolitan region and often combines public and private infrastructure. They are implemented by service providers, municipalities or consortiums and rely heavily on fiber optics today. When describing a computer network, the MAN is a key layer for delivering high‑capacity interconnection across urban environments.