lesson 2

Two Kinds of Network

Giving and Taking

In a network, some computers give things and others take.

Peer-To-Peer Networks

Your peers are people who are of the same importance as you – not more important, not less.

In a peer-to-peer network all computers give and take. None is special. They are peers.

Server Based Networks

Now one computer is special. It is called the server. It shares its resources – such as hard disk. All of the other machines are called workstations (or clients). They use the resources given by the server.

Sometimes a big server based network will have more than one server. It is still server based.

Networking Software

Just connecting two computers together with a cable will not let them share resources. To do this we must put networking software on both machines.

Networking software has two parts:

Server Software:	This software runs on the server. It teaches the server how to give – how to share its resources. This is called ‘the network operating system’ or maybe ‘the Server service’.
Client Software:	This teaches the workstation how to take. It is this software that makes your workstation think it has a drive H: when really drive H: is on a server. This software is called a redirector, requester or simply a ‘network client’.

Network Security

When a user saves her work on a computer, she expects that it will be private. No one else should be able to see her files. Keeping private things private is called network security.

Network security is a job of the server networking software.

Peer-To-Peer Or Server Based?

	Peer-To-Peer	Server Based
Advantages	Cheaper. No special server needed. No one needed to manage the network(?)	Administrator manages security centrally. Files are saved centrally so backup is easy. Applications are installed in just one place – so less work.
Disadvantages	No single person is responsible for controlling security – each user is responsible for security on her machine.	More expensive. One (or more) machines must be used as server. Need an Administrator to look after the server.
When To Use	Only when network will stay small (< 10 users) and security is not important.	When 10 or more users, or when security is important.

Hybrid Networks

A hybrid is not pure – it is a mixture.

As well as the two network main types studied above, it is also possible to have a hybrid network. Here there will be some specialized servers but some clients will also share their resources, like in a peer-to-peer network.

The Most Popular Products

Peer-To-Peer Networks

A computer in a peer-to-peer network needs both server and client software : it must give and take. Both current Microsoft client operating systems (Windows 95 and Windows NT Workstation) have this ability built in. No further software is needed.

Server Based Networks

Two companies dominate the PC server software market:

1. A company called Novell sells a system called NetWare. We use this system for our staff and student networks. In the past this has been the most popular choice.

2. Microsoft sells a system called Windows NT Server. This is getting more popular all of the time. This is the system we study in the BIT program.

Both companies supply matching client network software for all popular client operating system.

Specialized Servers

In a big network there may be several servers each doing a different jobs:

NT Is Two Products

Microsoft sells two versions of NT:

NT Workstation	This can be used on a stand-alone PC or on a PC in a peer-to-peer network.
NT Server	This is intended for use on a server in a server based network.

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