Page 22 - M. Abrahim Thesis

Chapter (2) Network Fundamental and Layered Network Architecture

WANs are designed to do the following:

• Operate over large, geographically separated areas
• Allow users to engage in real-time communication with other users
• Provide full-time remote resources connected to local services

• Provide e-mail, World Wide Web, file transfer, and e-commerce services

Here are some common WAN technologies:

• Modems
• Integrated Services Digital Network (ISDN)
• Digital Subscriber Line (DSL)

• Frame Relay

• T (U.S.) and E (Europe) carrier series—T1, E1, T3, E3, and so on
• Synchronous Optical Network (SONET)—Synchronous Transport Signal level 1
(STS-1) (Optical Carrier [OC]-1), STS-3 (OC-3), and so on

https://www.youtube.com/watch?v=6TF2ph6jiEI

2.4.3 Metropolitan-Area Networks (MANs)

A MAN is a network that spans a metropolitan area, such as a city or a suburban area.
MANs are networks that connect LANs separated by distance and that are located within a
common geographic area, as shown in Figure 2-3.
For example, a bank with multiple branches might use a MAN. Typically, a service
provider connects two or more LAN sites using private communication lines or optical services.
A MAN also can be created using wireless bridge technology by beaming signals across public
areas. The higher optical bandwidths that are currently available make MANs a more functional
and economically feasible option than in the past.
The following features differentiate MANs from LANs and WANs:

• MANs interconnect users in a geographic area or region larger than that covered
by a LAN but smaller than the area covered by a WAN.
• MANs connect networks in a city into a single larger network (which can then also
offer efficient connection to a WAN).
• MANs also are used to interconnect several LANs by bridging them with
backbone lines.

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