Metro Ethernet is essentially the use of carrier Ethernet technology in a metropolitan area that connects subscribers and businesses to a wide area network (WAN) and the Internet, or connects branch offices to an Intranet.

The most widely installed local area network (LAN) technology, Ethernet itself is designed to support high bandwidths with fine granularity and functions as a family of frame-based computer networking technologies for LANs. Ethernet stations are able to communicate by the sending of individual blocks of data, or data packets. Each Ethernet station receives a MAC address, which specifies both the destination and the source of each data packet. Prevalent in corporate and residential networks, Ethernet-based access networks are cost-effective and easy to implement into a customer network, thus driving its ubiquity.

A typical metro Ethernet system consists of a collection of Layer 2 and/or Layer 3 switches and/or routers that are connected through cable or optical fiber. Ethernet deployed in a metropolitan access network (MAN) is used as pure Ethernet, Ethernet over Synchronous Digital Hierarchy (SDH), Ethernet over Multiprotocol Label Switching (MPLS) or Ethernet over DWDM. Pure Ethernet is comparably inexpensive to the latter technologies.

A connection is made at a user-network interface (UNI) installed by the service provider, with one side consisting of the customer equipment, and the other being the metro Ethernet network. Functioning almost like a “wired” network connection between two locations, an Ethernet Virtual Connection makes the path between the interfaces possible and maintains the Ethernet MAC address and frame contents unchanged in order to establish Layer 2 connectivity between locations.

Corporations, government agencies and academic institutions in large cities like Washington, D.C., Baltimore and New York City have deployed metro Ethernet to achieve high-speed, secure and affordable connectivity. It has become the service of choice for many companies -- medical groups in particular, which normally consist of several hospitals, diagnostic centers and clinics -- that have two or more separate businesses in a local area.

The Metro Ethernet Forum (News - Alert) has been established to accelerate the adoption of carrier Ethernet networks and services. Consisting of more than 150 leading service providers, local exchange carriers, network equipment vendors and other networking firms dedicated to Metro Ethernet, the forum aims to create technical specifications and implementation agreements to promote the deployment of carrier Ethernet around the globe.

Tammy Wolf is a TMCnet web editor. She covers a wide range of topics, including IP communications and information technology. To read more of her articles, please visit her columnist page.

Edited by Jennifer Russell