Networks

A Guide to Networks

Networks & Stand-Alone Computers

Networks

A network is a bunch of computers that are linked together to share hardware (the physical components of a computer), software (an application/program) and data (information without context). Most computer networks have at least one server, which is a powerful computer that provides one or more services to a network and its users (e.g. file storage and email).


Advantages:

  • You are able to share devices such as printers between all the computers part of the network so you save money.
  • Software licenses are usually cheaper.
  • Files can be shared easily between users.
  • Network users are able to communicate by email and instant messenger.
  • Security is good, so users are unable to see other users' files, unlike on stand-alone computers.
  • Data is easy to backup, because it is all stored on the file server


Disadvantages:

  • Network cabling and file servers are expensive.
  • It is complicated to manage a large network, so a trained network manager is usually required.
  • If the file server breaks down it means that files on the server become inaccessible, email might still work if it is on a separate server. The computers can still be used, but they would be isolated.
  • If one computer gets a virus, then the virus could spread to other computers throughout the network.
  • Security procedures such as a firewall should be put in place, encase the network is hacked, especially if it is a wide area network.
  • There is a risk that traffic will slow down the computers.

Stand Alone Computers

Advantages:

  • If the computer is affected by a virus, no other computers will be affected.
  • It's more private than a network, because your data can't be accessed by other computers.
  • Traffic won't slow down the computer.
  • It is less complicated to set-up and use than a network, so you don't need to be an expert in IT.
  • You save money, because you don't need to buy a network cable or a file server.


Disadvantages:

  • If you want to install new software you have to install it on every computer separately.
  • You are unable to share storage with other computers.
  • You are unable to share back-up with other computers.
  • Software licenses are generally more expensive than when using a network.
  • You cannot use email or instant messenger to communicate with other computers.
  • You need a separate printer and other similar devices for each computer you use.

Local & Wide Area Networks

LANs

LAN stands for Local Area Network. A LAN covers a small area such as one site or building (e.g. a school or college). LANs are often connected to WANs, for example, a school network could be connected to the Internet.

WANs

WAN stands for Wide Area Network. A WAN covers a large geographical area. Most WANs are made from several LANs connected together. The Internet and a network of bank cash dispensers are examples of WAN. WANs can be connected together using the Internet, leased lines or satellite links.

Bus, Ring & Star Networks

Bus Network

In a bus network all the workstations, servers and printers are joined by one cable called the bus. At each end of the cable a terminator is fitted to stop signals reflecting back down the bus. A bus network, connecting several workstations, servers and printers.


Advantages:

  • It's easy to install.
  • It's cheap to install, because it doesn't require much cable.


Disadvantages:

  • If the main cable fails or gets damaged the whole network will fail.
  • As it doesn't require much cable as more workstations are connected the performance of the network will become slower because of data collisions.
  • Every workstation on the network "sees" all of the data on the network. This is a security risk.

Ring Network

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


Advantage

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.


Disadvantage

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

Star Network

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

A star network, where devices are connected to a central hub or switch


Advanatages:

  • It is very reliable, so if one cable or device fails then all the others will continue to work.
  • High performing as no data collisions can occur.


Disadvantages:

  • Expensive to install as this type of network uses the most cable (network cable is expensive).
  • Extra hardware required (hubs or switches) which adds to cost.
  • Tf a hub or switch fails all the devices connected to it will have no network connection.