In my last article about computer networking, I mentioned about LAN or the Local Area Network. MAN or the Metropolitan Area Network is basically a bigger LAN. The technology used in LAN and WAN are the same. When LAN is restricted to a building or a few kilometers, WAN can basically serve as a backbone for connecting many office networks within a geographical area together.
It supports video as well as audio. this makes it suitable for certain cable TV networks. The design simplicity of MAN comes from the fact that there is no switching in involved. There is a standard that is adopted for all metropolitan area networks. It is Distributed Queue Dual Bus (DQDB) or IEEE 802.6.
There are basically two buses in a DQDB. One on the upper end and one on the lower end. Each of theses buses have a head end which indicates the direction of information flow. If you want to send information to a computer which is situated to the right of the host computer, then the upper bus is chosen. The lower one for communicating with computers to the left of the network.