Page 96 - DLIS408_INFORMATION_TECHNOLOGY-APPLICATIONSL SCIENCES

Unit 8: Network Media

Notes

Notes MANs geographic scope falls between a WAN and LAN. MANs provide Internet
connectivity for LANs in a metropolitan region, and connect them to wider area
networks like the Internet. It can also be used in cable television.

Implementation

Some technologies used for this purpose are Asynchronous Transfer Mode (ATM), FDDI, and
SMDS. These technologies are in the process of being displaced by Ethernet-based connections
(e.g., Metro Ethernet) in most areas. MAN links between local area networks have been built
without cables using microwave, radio, or infrared laser links.

Did u know? Most companies rent or lease circuits from common carriers due to the fact that
laying long stretches of cable can be expensive.
DQDB, Distributed-queue dual-bus, is the metropolitan area network standard for data
communication. It is specified in the IEEE 802.6 standard. Using DQDB, networks can be up to 20
miles (30 km) long and operate at speeds of 34 to 155 Mbit/s.

8.2.1 The Benefits of Metropolitan Area Network

Technology is continually advancing in this modern world and almost everyday, new technologies
are innovated and released out of the market. Advancement of technology is visible in the field of
computer networking. If Local Area Network was the only invention yesterday, it has already
progressed to a higher version which is the Wide Area Network. To bridge the two types of
network, one of the newest technologies today is MAN - Metropolitan Area Network.
The Metropolitan Area Network is designed to connect networks in a metropolitan area, city,
campus, community, etc. It is wider than the Local Area Network which can only be used in one
building, floor or wide room. But, it is not as big as the Wide Area Network which goes beyond
one area or city to another location. The coverage of Metropolitan area network in terms of
geography is between LAN and WAN.
MAN can cover several blocks and buildings depending on the communication channels of an
area. It can reach from 5 to 50 kilometers in one area. The MAN may be used to connect several
LAN in order to create a big network. That is why it is often used in business establishment that has
several branches near each other. Universities and large campus also use the Metropolitan Area
Network nowadays.
To connect several Local Area Networks, MAN uses backbone line usually made up of fiber optic.
Fiber optic runs in subway tunnels in order to connect the networks in an area using MAN. The
advantage of using fiber optic is it can be replaceable with other types of fiber with higher quality.
Fiber will be replaced once in a while as needed or there is need to upgrade to another advance
type of network in the future.
Some Metropolitan Area Network owners use infrared or radio laser links. It is because using
cables may be expensive especially that it has to cover a couple of kilometers to link networks. The
maximum distance that MAN can handle is 50 kilometers and a fiber optic cable this long will be
very expensive to install. Those organizations or campuses using MAN with just few distances in
between networks can use the cables.
Using MAN is an advantage because it has high speed network access. It serves several protocols
such as IEEE 802.6 Distributed Queue Dual Bus Defined (DQDB), IEEE 802.16 Broadband Wireless
MAN Standard (WIMAX), Asynchronous Transfer Mode Protocol (ATM) and many more. Among
all protocols, the standard one used in MAN is the DQDB where it allows up to 30 kilometer
distance between networks with speed of 34-155 Megabytes per second.

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