Network Resource

Network Topologies, WANS and LANS

Networks

A computer network is a number of computers linked together. There are two main types:

LAN - Local area network

WAN - Wide area network


A LAN covers a small area such as one site or building.


A WAN covers a large geographical area. Most WAN's are made from several LAN's connected together.

Advantages of networks

  • You can share devices like printers - which saves money.
  • Software will be cheaper when buying for a network of computers.
  • Within a network files can be shared and you can communicate through email and instant messenger.
  • Data is easy to backup and is stored on the file server.

Disadvantage of networks

  • Purchasing all the equipment needed can be expensive.
  • It can be very complicated organizing the network and keeping it running.
  • If the file server breaks down you can' access the files on the server. The computers won't be connected anymore.
  • Viruses can spread to other computers through the network.

Topologies

Bus Topology

In a bus network all the workstations, servers and printers are connected to one cable - the bus. At the end of the cable there is a terminator to stop the signals going back down the cable/ bus. If the cable/ connection breaks it affects all the computers.

Ring Topology

In a ring network each device is connected to two others so that it forms a circle/ring. This is how the signal is passed round. Each packet of data only travels in one direction. If the connection is broken between two devices it affects all the computers.

Star Topology

In a star network each device has its own cable that connects it to a hub/switch. A hub sends every packet of data to every device whereas a switch only sends data to the destination device.

Advantages of:

Bus Topology

  • It is easy to set up and manage.
  • It is best suited for small networks.


Ring Topology

  • It transfers data quickly even if there are a large number of device because the data only flows in one direction so data collisions won't happen.


Star Topology

  • Very reliable- if one connection fails then the others will still work.
  • Transfers data quickly as there won't be any collisions.

Disadvantages of:

Bus Topology

  • The cable length is limited, this limits the numbers of stations that can be connected.
  • Can only perform well for a limited number of stations.


Ring Topology

  • If the main cable fails or any device is faulty the whole network will fail.


Star Topology

  • Expensive to install- as it requires the most cable.
  • Extra hardware required- hubs or switches cost extra.
  • If the hub or switch fails then all the devices connected to it will have no network connection.