Networks

LANs, WANs and Topologies

LANs

A LAN, also known as Local Area Network, is a network that covers a small area such as a school or a site.


WANs

A WAN also known as Wide Area Network, is a network that covers a large geographical area, usually made from a collection of LANs connected together. For example the internet is a WAN as is a network of bank cash dispensers.

WANs can be connected to each other via the internet.

Advantages and Disadvantages of Networks

Advantages:

  • Saves money by sharing hardware such as printers and photocopiers
  • Files are easier to share and the data is easier to back up
  • Network users can communicate via e-mail and instant messenger
  • Users are unable to see other users’ files unlike on stand-alone machines but it can still be hacked

Disadvantages:

  • The equipment needed to set up a network can be expensive
  • If the file server breaks down, all the files on the server would become inaccessible to anyone, also you wouldn't be able to communicate between computers anymore, they would become stand-alone
  • Viruses can spread one computers to the other computers in network
  • There is a danger of hacking, particularly with wide area networks

Topologies

The Bus Network

In a bus network all the workstations, servers and printers are joined to one cable, like a bus route.

Advantages:

  • Easy and cheap to install

Disadvantages:

  • If the main cable fails or is damaged, the network will fail
  • As more workstations are added to the network, the performance gets slower
  • Every workstation “sees” all data so it becomes easier to hack

The Ring Network

In a ring network each computer, printer, server etc. is connected to two other devices, this forms a ring for the signals to travel around. Each piece of data on the network travels in one direction and each device receives the data in turn until the destination device receives it.

Advantages:

  • This type of network can transfer data quickly, even if there are a large number of devices connected because the data only flows in one direction, so there won’t be any data collisions.

Disadvantages:

  • If the main cable fails or any device is faulty then the whole network will fail
  • Only one device needs to be hacked to access all the data being sent round

The Star Network

In a star network each device on the network has its own cable that connects to a switch or hub. This in turn send out the data relevant to each device instead of sending it though others first.

Advantages:

  • It is very reliable because if one cable or device fails then all the others will continue to work without it affecting them
  • It's also high performing as no data collisions can occur
Disadvantages:

  • This is the most expensive to install as it requires the most cable
  • Extra hardware required (hubs or switches) which adds to cost
  • If a hub or switch fails all the devices connected to it will have no network connection

Benefits of networking

File sharing

Increased storage capacity

Resource sharing

Increased cost efficiency