ICT Infrastructure design and implementation
Often ICT Infrastructure design is not given sufficient
focus which can result in more expensive capital and running
costs, or the network needing constant modification during
its lifetime. A wired network is best suitable option in
case a client’s requirement is a reliable and a robust
network operational in all conditions. A wireless network
should be installed in a place where the primary purpose
is seamless mobility and also where laying a wired network
is very expensive and difficult. There are all different
kinds of wireless protocols used for different types of
wireless networks, but if you want to build a WLAN for your
home or office the type of protocol you'll want to use is
called 802.11b.
Based on the requirements and future expansions,
an appropriate network platform whether wired or wireless
or a combination of both of them should be selected. Basically
the networks can be classified into three types:
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Local area networks. |
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Metropolitan area networks. |
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Wide area networks. |
There are different types of transmission
media may be employed as the basis of a communication channel
and they are Two-wire open lines, twisted pair lines, Coaxial
cable, Optical Fibre. The architectures that are commonly
used in the network design are mentioned below:
Hierarchical Networks: This generally involves
a high speed computer which is serviced by a number of lower
power computers which are in turn serviced by a number of
lower power computers (typically microprocessors).
Bus: Ethernet is a proprietary name for a Bus network, originally
developed by Xerox, Intel and DEC. In its simplest form
it comprise of a single communication channel to which all
computers are connected. Fast Ethernet and Giga bit Ethernet
are higher speed versions of the basic Ethernet.
Token Ring: A ring operates on a technique
known as token passing. A small frame circulates around
the ring all the times ad contains the token and the node
whishing to transmit should first acquire the token to send
the data. FDDI is a fibre optic version of the token ring
standard with a few important modifications. This mainly
consists of counter rotating rings , known as primary ring
and secondary ring. Data usually travels though the primary
ring with the secondary ring acting as a back-up. FDDI uses
Time Division multiplexing to break up the available 100
Mpbs into 17 separate channels, one at 765kbps and 16 wide
band channels at 6.144 Mbps. The 765kbps channel is reserved
for token passing. The 16 wide band channels can be designated
as either token-passing data channels or as separate connection
oriented virtual circuits for speech or video (or other
time critical data).
Another MAN standard like FDDI is DQDB
(Distributed Queue Bus) and it consists of two parallel,
unidirectional buses snake through a city, with stations
attached to both buses in parallel.
ATM (asynchronous transfer mode) is packet switched technology,
originally developed for use in wide area network. It uses
small, 53 byte length packets and operates on a connection
oriented basis that is a switched virtual circuit is established
prior to any transmission. It was originally developed as
the basis for switching and routing in Broadband ISDN networks
but has found some application in LAN’s as a high
speed backbone and this is used especially for critical
transmissions.
Convergence:
Convergence" describes a networking
environment where voice, video and data transmissions are
integrated within a single, unified system - often referred
to as a "multiservice network." More specifically,
this network is based on Internet Protocol (IP) standards,
the same packet-based architecture that drives the World
Wide Web.
Network convergence enables an organization
to use services like IP telephony (also called "Voice-over-IP",
or VoIP), unified messaging (voice and e-mail), videoconferencing,
and a host of other applications that seamlessly integrate
voice, video and data communications. Moreover, the converged
network utilizes a "distributed" framework to
provide this functionality to users. Whether deployed over
a Local-Area Network (LAN) or, with the appropriate broadband
infrastructure, across a Wide-Area Network (WAN), data and
application information for all services reside on centralized
servers rather than terminal devices, and are distributed
to the end user over the network to IP-enabled devices (e.g.,
IP phones). Again, it's the same architecture that supports
the browser-based client-server model common to the Internet.
Perhaps most importantly, by consolidating
the separate networking systems and services for voice,
video and data, convergence means an organization has only
one cost-effective, unified network infrastructure to design,
deploy, manage and support.
