Subject Navigation

• ictWeb Home
• General Topics Home
• Input & Output Devices
• Internet and www
• Intranets
• Legislation
• Lifecycle Models
• Wireless Networks
• Web Design
• Digital Cameras

Information Communication Technology and Related Topics

Networks

There are several types of network. These are known as network topologies.

The most common are:

• bus
• ring
• star
• mesh

Bus Network

All the devices (nodes) are attached to a single cable with the ends sealed. If one node sends a message to another node, the message travels up and down the cable until recognised by the receiving node, but all the nodes on this network can see the message. It is necessary to have an addressing mechanism so that each node understands which messages it is to receive and which it is to ignore.

The advantages of a bus network are:

• as there is only one cable it's easy, quick and cheap to set up.
• nodes can be added easily.

The disadvantages are:

• If the network fails it can be difficult to find a fault because no central distribution points exists.
• The break can be hard to find.
• Cable breaks can disable the entire network because they remove the required sealed ends from each of the two cable fragments.

Ring Network

The ring topology is a physical, closed loop consisting of point-to-point links where all devices are connected to one another in the shape of a closed loop, so that each device is connected directly to two other devices, one on either side of it. In the diagram, each node on the ring acts as a repeater. It receives a transmission from the previous node and amplifies it before passing it on to the next node.

Because of this repeating function ring topologies are relatively expensive and difficult to install, but they are very effective and can span large distances.

The advantages of a ring network are:

• as each node amplifies the signal, quality is high.
• it can span large distances.

The disadvantages are:

• A break in any cable can bring the whole network down.
• They are expensive and difficult to install.

Star Network

The most popular network where all devices are connected to a central hub. Star networks are relatively easy to install and manage, and new nodes can be added. but bottlenecks can occur because all data must pass through the hub.

The advantages of star network are:

• Each device has its own cable. This makes it easy to isolate individual devices from the network by disconnecting them from the wiring hub.
• All data goes through the central point, which can be equipped with diagnostic devices that make it easy to trouble shoot and manage the network.
• Hierarchical organization allows isolation of traffic on the channel. Traffic from those heavily used computers can be separated from the rest or dispersed throughout for a more even flow of traffic.

The disadvantages are:

• Because point-to-point wiring is used for each node, more cable is required, increasing expense
• A hub failure can mean the network fails.

Mesh Network

In a mesh network every node is connected to another node as in a ring network, but other connections can be made such that non-adjacent nodes can be directly connected. This is particularly of benefit if, in addition to a main network, specialised work groups may also share a network within the main network.

See also wireless networks

Copyright © ictWeb.org 2004