Networks are merely a means to allow computers
to communicate with one and other. That can be two
computers in your home or a hundred computers in your office.
Since you are reading this, you are using the largest existing
network in the world, the Internet.
In our discussions we will be connecting
Personal Computers, PCs, into an environment where they utilize
common data, common peripheral devices such as printers or
modems, common software programs and sharing these resources.
These are examples of simple
peer-to-peer networks, where only two computers are connected by
a single cable. In these types of networks only a network
card in each computer and a connecting cable is required.
In these examples although you have two computers, they share
the resources of data, modem access, printer and other
components.
A peer-to-peer network
requires a special cable, different from a normal network patch
or connecting cable. This cable is called a
"cross-over" or "cross-pin" cable.
If your network contains three
or more computers, then you are required to add one more
component, either a hub or a switch.
A network connected with
either a hub can have two or more computers connected. The
hub allows for additional computers to be added to the network
at any time. All that is required is an additional cable
connected from the hub or switching hub to a network card inside
of the new computer. Each computer, printer, or other
peripheral device that is connected to the network is called a
node. Networks can have tens, thousands, or even millions of
nodes.
Like most things, networks are
are assembled according to certain rules. Cabling, for example,
has to be a certain length, each cabling strand can only support
a certain amount of network traffic, etc. The rules that govern
how a network is set up is called its topology. The most
popular topology in use today is called Ethernet, which consists
of computers and peripherals cabled together in specific ways.
Ethernet is relatively inexpensive, easy to set up and use, and
very, very fast.
Ethernet networks are
categorized by how fast they can move information. Speed is
expressed in megabits per second (or Mbps), where one
"bit" is equal to 1/8th of a character, letter, or
number. There are currently two Ethernet speed categories.
Standard Ethernet operates at a fast 10Mbps, which is quick
enough for most networking tasks. Fast Ethernet, by contrast,
races along at 100Mbps, making it ideal for desktop video,
multimedia, and other speed-hungry applications. The new
technology behind Fast Ethernet, which was introduced in the
beginning of 1995, is not readily compatible with standard
Ethernet. Making the two "talk" with each other
requires special equipment (see switching hub
below) and some knowledge of internetworking. If you're
building your first network, decide whether to go with standard
or Fast Ethernet before you begin shopping around for network
hardware and software. Unless you plan on using video,
multimedia, or heavy graphics software, plan on using standard
Ethernet. For more information on standard and Fast Ethernet,
see the Cabling & Hubs section.
Cabling Basics
The two most popular types of network cabling
are twisted-pair (also known as 10BaseT) and thin coax (also
known as 10Base2). 10BaseT cabling looks like ordinary telephone
wire, except that it has 8 wires inside instead of 4. Thin coax
looks like the copper coaxial cabling that's often used to
connect a VCR to a TV set.
Which type of cabling
is best for you?
Thin coax and 10BaseT can both be used exclusively or together,
depending on the type of network that you're putting together.
Small networks, for example, may want to use 10BaseT cabling by
itself, because it's inexpensive, flexible, and ideal for going
short distances. This is recommended for home networks as
it is the easiest.
Larger networks (usually with
10 or more computers) may use a thin coax backbone with small
clusters of 10BaseT cabling that branch off from it at regular
intervals.
I will bet you have lots of
questions already, here are a few quick answers:
Network
Adapter Card
A network computer is connected
to the network cabling with a network interface card, (also
called a "NIC", "nick", or network adapter).
Some NICs are installed inside of a computer: the PC is opened
up and a network card is plugged directly into one of the
computer's internal expansion slots. 286, 386, and many 486
computers have 16-bit slots, so a 16-bit NIC is needed.
Faster computers, like high-speed 486s, Pentiums,
PentiumII and PentiumIII, all have 32-bit, or PCI slots. These
PCs require 32-bit NICs to achieve the fastest networking speeds
possible for speed-critical applications like desktop video,
multimedia, publishing, and databases. And if a computer
is going to be used with a Fast Ethernet network, it will need a
network adapter that supports 100Mbps data speeds as well. These
cards are often referred to as 10/100cards.
If a PC lacks expansion slots (which is
true with portable PCs), special network adapters are used. A
PCMCIA network adapter connects a PC to a network if the PC has
a credit card-sized PCMCIA expansion slot, while a pocket
adapter connects a PC to a network through the its printer port.
HUB
The central connecting device
is called a hub. A hub is a box that is used to gather groups of
PCs together at a central location with 10BaseT cabling. If
you're networking a small group of computers together, you may
be able to get by with a hub, some 10BaseT cables, and a handful
of network adapters. Larger networks often use a thin coax
"backbone" that connects a row of 10BaseT hubs
together. Each hub, in turn, may connect a handful of computer
together using 10BaseT cabling, which allows you to build
networks of tens, hundreds, or thousands of computers.
Like network cards, hubs are available in
both standard (10Mbps) and Fast Ethernet (100Mbps) versions.
SWITCHING
HUB
The Switching hub, sometimes
called a "Switch" is a more advanced unit over the
basic hub. In a basic hub, all the computers connect to it
and the speed of the network is defined by the slowest computer
network card connected. If you have 10 100Mbps cards on
the network and just on 10Mbps card, the system cannot run
faster than that one 10Mbps card. There in comes the
Switching hub. This hub treats each network card
independently and in the matter of the 10 100Mbps network with
the one 10Mbps network card, the Switching hub allows all of the
faster connections to remain at the higher speed and still
interact with the 10Mbps system.
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