CHAPTER 1

INTRODUCTION TO NETWORKING

Lesson 1: What is a Network? . . . . . . 4

Lesson 2: Network Configuration . . . 12

Lesson 3: Network Topology……….. 23

What is a Network?

A Network is as simple as connecting two computers together by a piece of cable. The main purpose

to Networking is share data bases, resources, peripherals, and any other applications needed

in the workgroup.

Why use a Computer Network?

Computer networks achieve these goals in three primary ways by sharing data, hardware and software,

and centralizing administration and support.

More specifically computers that are part of a network can share: Documents, E-mail messages,

Word-processing software, Project-tracking software, Photographs, Printer, Fax Machines, Modems,

CD-ROM and Hard Drives. It is a great savings to a company to have Networks, providing they are

set-up correctly, and administered correctly.

The Two Major Types of Networks: LANs and WANs

Computer networks are classified into one of two groups, depending on their size and function.

A local area network (LAN) is the basic building block of any computer network. A LAN can range

from simple ( two computer connected by a cable) to complex (hundreds of connected computers

and peripherals throughout a major corporation).

A wide area network (WAN) on the other hand, has no geographical limit.

The two types of Network Configurations

The distinction between peer-to-peer and server-based networks is important because each type

has different capabilities. The type of network you choose to implement will depend on factors such

as the:

a) Size of the organization

b) Level of Security required

c) Type of business

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d) Level of administrative support available

e) Amount of network traffic

f) Needs of the network users

a) Network Budget

PEER-TO-PEER NETWORKS

In a peer-to-peer network, there are no dedicated servers, and there is no hierarchy among the computers.

All the computers are equal and each computer functions as a both a client and a server. There is no

systemadministrator, and all the data on each computer is shared between the computers.

Peer-to-Peer Networks have their limits, you can only have 10 users on the network, but there can be

some exceptions made. But, the Microsoft limit for the peer-to-peer will be 10. These Networks are

easily set-up and relatively inexpensive.

Operating Systems

In a peer-to-peer network, the networking software does not require the same standards of performance

and level of security as the networking software designed for dedicated servers. A user on a peer-to-peer

system act as their own administrator for their own computer. The peer-to-peer network is useful when

there are 10 or less users, security is not an issue, growth is not a factor etc.

Sharing Resources

All users can share any of the resources in any manner they choose. These resources include data in

shared directories, printer, fax cards and so on.

SERVER-BASED NETWORKS

In a environment with more than 10 users, a peer-to-peer network will not work. It will be necessary

to go with a server-based network. A dedicated server is one that functions only as a server and is

not used as a client or workstation. Servers are describes as dedicated because they are not themselves

clients, and because they are optimized to service requests from network clients quickly and to ensure

the security of files and directories.

File and Print Servers

File and print servers manage user access and use of file and printer resources. File and print servers

are used for file and data storage.

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Application Servers

Application servers make the server side of client/server applications, as well as the data available to

the clients. With an application server, the database stays on the server and only the results of a

request are downloaded to the computer making the request.

Mail Servers

Mail servers operate like application servers in that there are separate servers and client applications,

with data selectively downloaded from the server to the client.

Fax Servers

Fax servers manage fax traffic into and out of the network by sharing one or more fax modem boards.

Security

Security is often the primary reason for choosing a server-based approach to networking. In a

server-based environment, one administrator who sets the policy and applies it to every user on the

network can manage security.

DESIGNING A NETWORK TOPOLOGY

Topology is like a map, or the physical layout of the computers, cables, and other components on the

network.

Standard Topologies

There are four types of topologies, bus, star, ring and mesh. A Bus topology consists of several computers

or devices connected to a single cable. A Star topology uses a hub as a central device to connect the

computers. A Ring topology, is not actual, usually only in theory, but this type of network supposedly

forms a ring. A mesh topology is redundant in that it doubles the wire, and it is very expensive for

that reason.

Bus Topologies

The bus topology is often referred to a linear bus, because the computers are connected in a straight

line. Each end of the line on the computer must have a terminator attached. This will prevent the

signal bouncing between the computers forever. Because only one computer at a time can send data

on a bus network, the number of computers attached to the bus will affect network performance.

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NETWORK EXPANSION

A component called a barrel connector can connect two pieces of cable together to make a longer piece

of cable. This connector should be used sparingly, too many patches in the line will cause some problems.

A device called a repeater can be used to connect two cable. A repeater actually boosts the signal before

it sends the signal on its way.

Star Topology

In start topology the cable segments from each computer are connected to a centralized component

called a hub. The only disadvantage of this topology is if the hub is down, the entire network is down.

This is a physical star layout, and a logical bus format. The star network offers the advantage of

centralized resources and management.

Ring Topology

The ring topology connects computers on a single circle of cable. Unlike the bus topology there are no

terminated ends. A network’s physical topology is the wire itself. A network’s logical topology

is the way it carries the signals on the wire.

Token Passing

One method of transmitting data around a ring is called token passing. Each network has only one

token. The token is passed from computer to computer until it gets to a computer that has data to

send. The token has full control of the data line. The data passes by each computer until it finds

the one with an address that matches the address on the data.

Mesh Topology

A Mesh topology offers superior redundancy and reliability. If one computer fails, there is back-up

wire to access, and makes trouble-shooting easier. The only disadvantage will be cost, double the

cabling.

Hubs

One network component that has become standard equipment in networks is the hub. Most hubs

are active, that is they regenerate and retransmit signals in the same way as a repeater does. There

are also passive and Advanced Hubs.

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Advantages to Hub-based Topologies

There are some benefits such as wiring systems can be changed or expanded as needed. Also different

ports can be used to accommodate a variety of cabling types. Next, the monitoring of network activity and

traffic can be centralized.

Star Bus Topologies

The star bus is a combination of the bus and star topologies. In a star-bus topology, several start

topology networks are linked together with linear bus trunks. If one computer goes down, it will

not affect the rest of the network.

Star Ring

The star ring appears similar to the star bus. Both the star ring and the star bus are centered in a hub that

contains the actual ring or bus.