Metropolitan Area Networks

Abstract

AbstractA metropolitan area network (MAN) is a shared network that covers the distances in most cities. The applications of MANs and the techniques that are used for communications is rapidly changing. MANs were originally used to interconnect the users in a single organization, and several specialized networks were developed. However, the Internet has increased the demand for high‐speed communications to individual consumers. In consumer applications, cost is particularly important. The networks use existing infrastructure or infrastructure that can be deployed with minimal investment and use access devices that are popular in other applications and therefore cost less than new devices.The first generation of MANs used protocols and network topologies that are similar to local area networks but are specifically designed to span the greater distances and operate at the higher transmission rates that occur in a MAN. We describe three of these protocols: the American National Standards Institute (ANSI) X3T9 standard, fiber distributed data interface, (FDDI), the IEEE 802.6 standard, dual bus distributed queue protocol, (DQDB), and an experimental network, the Manhattan Street Network, (MSN).Currently, the most widely used MANs use the existing cable TV (CATV) network and easily deployed wireless networks. The CATV standards are not keeping pace with the applications. We describe the common characteristics of the applications and describe in detail an application that is based on Ethernet technology and that can be extended to carry packet voice communications. The IEEE 802.11 standard, wireless fidelity (WiFi), is the most widely used wireless access technology. This standard is described in detail, along with a competing access technique, Bluetooth, and the IEEE 802.16 standard that can be used to extend the range of wireless access techniques to the metropolitan area.In the conclusion we predict future changes. These changes are fueled by the need for improved reliability, the emergence of IP‐voice, the increased use of wireless technologies, the overuse of the cellular bands, the eventual deployment of fiber to the home, and a resurgence of ATM‐like, cell‐based transmission.