Network Environments


Background:

In this section you should be able to:


General Overview

A network is a collection of computers connected via cable or wireless technology.

Each stand-alone computer may be connected to a server or hub which in turn connects the computer to the whole network.

 


Networks vs Stand-alone:

Why use networks?

If a school/company have computers all over a building they can network them together so that documents can be sent to any computer in the network.

 

This makes it easier for people within the building to use any computer within the network to log-on to their user area and access their documents.

 

Advantages of using a network:

Disadvantages of using a network:


Introduction


Exercise 1:


Local Area Networks (LAN):

What is a Local Area Networks (LAN)?

Types of Local Area Network:

 

Peer to peer:
  • Simple network linking two or more computers, e.g.
    • home computer network
  • Each computer is of equal status
  • Resources and files are shared

image from: University of South Florida
Client-Server:

  • Server controls the network
    • more powerful comptuer
    • provides security
    • stores data
    • stores programs
  • Cluster of computers that access the network via the server
  • More complex network
  • More secure network
image from: Navaneeth Krishnan: The Jxta solution to P2P

 

Advantages of a client/server network:

 

Disadvantages of a client/server network:

 

LAN Technology Elements:

 

Element

Options

Restrictions

Comments

Topology

Bus

Optical Fibre not cost-effective

No active elements

Ring

Not CSMA/CD or broadband

Supports fibre

Star

---

Conforms to standard building wiring practices

Transmission medium

Unshielded twisted pair

Speed-distance limitation

Inexpensive; pre-wired; noise vulnerability

Shielded twisted pair

Speed-distance limitation

Relatively inexpensive

Baseband coaxial cable

---

Declining popularity

Broadband coaxial cable

Not with ring topology

High capacity; multiple channels; rugged; expensive

Optical fibre

Not cost-effective with bus topology

Very high capacity; security

Layout

Linear

---

Minimal cable

Star

---

Ease of wiring; availability

Medium access control

CSMA/CD

Not with ring topology

Simple; widely implemented

Token ring

---

High throughput; priority

 


Wide Area Networks (WAN):

What is a Wide Area Networks (WAN)?


Network Requirements:

Hardware:

Modems:

There are 2 types of modem, internal and external

 

Internal:

External:

Software:

Communications and topology:

 

Topology term given to the arrangement of the components of a network. It describes how computers, printers, servers and other devices are connected to each other.

 

British Computer Society: The BCS Glossary of ICT and Computing Terms.

11th ed. Harlow: Pearson Education, 2005.

 

Element

Options

Restrictions

Comments

Topology

Bus

Optical Fibre not cost-effective

No active elements

Ring

Not CSMA/CD or broadband

Supports fibre

Star

---

Conforms to standard building wiring practices


Exercise 2:


Exercise 3:



Exercise:

Now do the questions at the end of Chapter 29 of the text book