Network Topology

Network Topologies

The volume of data that can be transferred across a network at a given time is called its bandwidth. An expensive, high bandwidth network is able to transfer data much quicker than a low bandwidth one. The bandwidth is effected by the types of network cards and modems used as well as the amount and type of cable used.
Also, the way in which computers are connected together to form a network has a large effect on its speed and efficiency. There are a number of different ways to connect computers in a network - but these are the most common:

ring

Ring Topology

In this configuration the computers are connected together to form a ring shape so that none of the computers is more important than any of the others.
In this diagram the printers is attached to one of the computers in the network. This computer is called the print server and it handles all the printing jobs on the network.

The main disadvantage of the ring topology is that the whole network will be affected if there is a break anywhere in the network cabling.

an inexpensive network hub

Star Topology

The star topology has one powerful computer (or a special junction box called a hub) that controls the whole network. If the hub fails then the whole network fails. Another disadvantage of the star topology is that it uses a lot of cable. This make it an expensive network to set up (not only do you have to buy expensive network cables but you also have to install more trunking to keep the cables out of harms way).

However, the big advantage of the star network is that it is fast. This is because each computer terminal is attached directly to the central computer.

star
bus

Bus (or Line) Topology

In this topology network messages are sent to each terminal on the network - so if one of the terminals breaks then the others are not affected. If you want to send a message from computer A to computer B then all the computers will receive the message, however because you have included computer B's address, only computer B will pick it up and display it.

Like the ring topology there is no special computer on this network. It is popular because it is a simple as well as a relatively cheap and reliable topology.

Clients, Servers and Peers

In networks where one computer is more important than the others the controlling computer is called a server and the other computers on the networks are called clients. This type of network is called a client/server network.
In other networks, however, there isn't a more dominant, controlling computer. In these networks each computer has the same amount of control as any other, these are called Peer-to-Peer networks.

Extra Help for your Network

bridge

It won't be long before you need to add more terminals or extra filestore to your network making the whole network more complex. Help is at hand, though, in the form of bridges and routers.

A router is a device that directs the network messages as they travel around the cables. Like someone who is lost on a complicated road system, network messages can travel in many different directions taking a long time to get to their destination. The router makes sure message travel along the quickest, most efficient routes.

A bridge is a link between two networks that makes them appear to be one, large network. Many WANs are, in fact, collections of LANs linked together by bridges.

Now, answer these questions:

  1. What is the name for the amount of data a network can transfer ?
  2. What type of network has the computers linked in a circle ?
  3. Which network links all the computers to a single, common cable ?
  4. What type of network has a single main controlling computer or hub ?
  5. What is the name of a network where all terminals are equal ?
  6. What network has a controlling computer and terminals controlled by it ?
  7. What device links two networks together?
  8. What device controls the routes taken by network traffic ?
  9. What is a LAN ?
  10. What is a WAN ?

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