Network Topologies

The way networks are arranged is called a network topology. Networks can be a single topology or a mixture of more than one. Whatever the topology, each computer has to have a network address so that the packets of data know where to go. This is known as IP address, an example would be 192.168.0.128.

There are three basic types of network topolgy: Bus, Ring and Star.

Bus Network



This is the simplest way to connect workstations, servers and other components of a network by using a single cable. One or more of the workstations act as the File Server, whilst the other machines are used as workstations or terminals.

Advantages:

• Cheap
• Easy to install.

Disadvantages:

• If there is a problem with the cable, the entire network stops working.
• If many workstations are using the network at the same time, response can be very slow, thus frustrating users who want to work quickly. The technical term for data trying to travel simultaneously along the cable in different directions is called 'data collision'. A busy network will have many data collisions.

Ring Network

The workstations are attached to a cable arranged in a ring

Advantages:

• Very fast - all data traffic occurs in the same direction so there should be no data collisions.

Disadvantages:

• If a single machine is switched off then the network does not work. If the cable breaks, once again, the network does not work.

Star Network

Each workstation has its own direct line to the server. Connections to the server are made with hubs or switches.

Hubs connect many lines together.

Switches allow the network manager to connect certain workstations to specific servers.

Advantages:

• Reliable - if one connection fails, it does not affect others.
• Good performance, fewer data collisions as each workstation has its own line.
• Good Security - no workstation can interact with another without going through the server first.

Disadvantages:

• Expensive to install - lots of cables required.
• Installation is an expert job.
• Extra hardware required such as hubs, switches and wiring centres.

Star networks are normally preferred because of their reliability.