METROPOLITAN AREA NETWORKS
DEFINITION OF A METROPOLITAN AREA NETWORK
The IEEE (Ref. 1) defines a Metropolitan Area Network (MAN) as "a network for con-
necting a group of individual stations and networks (for example, local area networks
(LANs)) located in the same urban area." The following note was added: A MAN
generally operates at a higher speed than the networks interconnected, crosses network
administrative boundaries, may be subject to some form of regulation, and supports several
There are two basic but very different approaches to building a metropolitan area network.
The most straightforward, probably the most expensive, is to build an optical fiber network
around the urban area in question. The second is to use a radio or wireless network. A
fiber-optic network has excellent expansion capabilities assuming some dark fiber is placed
in the cable alongside of the operational strands. Even the operational strands' capacity
can be notably increased by adding WDM devices and possibly amplifiers. On the other
hand, a radio (or wireless)-based network can be re-sited fairly easily. This is much more
difficult to do with the optical fiber alternative.
If the metro area is large, say
>100-km circumference, LOS microwave may be a
consideration. Once installed, it would be costly to resite. If the circumference is small
<100 km), one of the IEEE 802 wireless LAN standards may want to be considered.
In this discussion three IEEE 802 Committee standards will be briefly outlined:
FIBER-OPTIC RING NETWORK
Typically, a fiber-optic ring network is created when a fiber-optic cable connects the
several nodes around the ring. We assume at the outset that each node connected to the
Fundamentals of Telecommunications, Second Edition, by Roger L. Freeman
2005 by Roger L. Freeman
13 METROPOLITAN AREA NETWORKS 13.1 DEFINITION OF A METROPOLITAN AREA NETWORK The IEEE (Ref. 1) defines a Metropolitan Area Network (MAN) as "a network for con- necting a group of individual stations and networks (for example, local area networks (LANs)) located in the same urban area."