Network
Cabling
Introduction
This section talks about the cabling used in
today's networks. There's a lot of different
type of cabling in today's networks and I am not
going to cover all of them, but I will be
talking about the most common cables, which
include UTP CAT5 straight through and crossover,
Coax and a few more.
Cabling is very important if you want a network
to work properly with minimum problems and
bandwidth losses. There are certain rules which
must never be broken when you're trying to
design a network, otherwise you'll have problems
when computers try to communicate. I have seen
sites which suffer from enormous problems
because the initial desgin of the network was
not done properly !
In the near future, cabling will probably be
something old and outdated since wireless
communication seems to be gaining more ground,
day by day. With that in mind, around 95% of
companies still rely on cables, so don't worry
about it too much :)
Let's have a quick look at the history of
cabling which will allow us to appreciate what
we have today !
The Beginning
We tend to think of digital communication as a
new idea but in 1844 a man called Samuel Morse
sent a message 37 miles from Washington D.C. to
Baltimore, using his new invention ‘The
Telegraph’. This may seem a far cry from today's
computer networks but the principles remain the
same.
Morse code is type of binary system which uses
dots and dashes in different sequences to
represent letters and numbers. Modern data
networks use 1s and 0s to achieve the same
result. The big difference is that while the
telegraph operators of the mid 19th Century
could perhaps transmit 4 or 5 dots and dashes
per second, computers now communicate at speeds
of up to 1 Giga bit, or to put it another way,
1,000,000,000 separate 1s and 0s every second.
Although the telegraph and the teletypewriter
were the forerunners of data communications, it
has only been in the last 35 years that things
have really started to speed up. This was borne
out of the necessity for computers to
communicate at ever ncreasing speeds and has
driven the development of faster and faster
networking equipment, higher and higher
specification cables and connecting hardware.
Development
of new network technology
Ethernet was developed in the mid 1970's by the
Xerox Corporation at its Palo Alto Research
Centre (PARC) in California and in 1979 DEC and
Intel joined forces with Xerox to standardize
the Ethernet system for everyone to use. The
first specification by the three companies,
called the 'Ethernet Blue Book', was released in
1980, it was also known as the 'DIX standard'
after their initials.
It was a 10 Mega bits per second system (10Mbps,
= 10 million 1s and 0s per second) and used a
large coaxial backbone cable running throughout
the building, with smaller coax cables tapped
off at 2.5m intervals to connect to the
workstations. The large coax, which was usually
yellow, became known as 'Thick Ethernet' or
10Base5 - the '10' refers to the speed (10Mbps),
the 'Base' because it is a base band system
(base band uses all of its bandwidth for each
transmission, as opposed to broad band which
splits the bandwidth into separate channels to
use concurrently) and the '5' is short for the
system's maximum cable length, in this case
500m.
The Institute of Electrical and Electronic
Engineers (IEEE) released the official Ethernet
standard in 1983 called the IEEE 802.3 after the
name of the working group responsible for its
development and, in 1985, version 2 (IEEE
802.3a) was released. This second version is
commonly known as 'Thin Ethernet' or 10Base2; in
this case the maximum length is 185m even though
the '2' suggest that it should be 200m.
Since 1983, various standard have been
introduced because of the increased bandwidth
requirements, so far we are up to the Gigabit
rate !
