Give an overview of computer networks, describing some of the different kinds of network

* Campus-area networks (CANs): The computers are within a limited geographic area, such as a campus or military base.

* Metropolitan-area networks (MANs): A data network designed for a town or city.

* Home-area networks (HANs): A network contained within a user's home that connects a person's digital devices

In addition to these types, the following characteristic is also used to categorise different types of networks:

Network Topologies

John Wobus (1994) has argued that the layout of the network cabling is called its topology. There are three main layouts which are Bus, Star and Ring, although it is possible to have a network which is a combination of any of the described topologies. In schools, the bus and the star are the most common topologies.

Bus

A bus network is an arrangement in a local area network (LAN) in which each computer (workstations or other devices) is connected to a main cable called the bus. Each computer is shown as a sphere, the bus appears as a heavy horizontal line, and connections to the bus appear as vertical lines. The illustration shows a bus network with five computers.

Advantages of a Bus Network:

• Easy to install - as the cable can be laid along the most effective path

• It uses least cable of all topologies, and there is no additional hardware needed

• It is in most cases the least expensive solution

Disadvantages of a Bus Network:

• More expensive cabling - because the line must be shared the cable has to have a high bandwidth.

• Not very fast - Addition of nodes negatively affects the performance of the whole network, and if there is a lot of traffic throughput decreases rapidly.

Star

A star network is a local area network (LAN) in which all computers (workstations or other devices) are directly connected to a common central computer. Every workstation is indirectly connected to every other through the central computer. In some star networks, the central computer can also operate as a workstation. The image below shows a star network.

Advantage of a Star network:

• Easy to install and to reconfigure

• If any workstation goes down, none of the other workstations will be affected

• Fault can be easily identified because an unusable link does not harm the entire system.

Disadvantages of a Star Network:

• If the central computer goes down, the entire network will suffer a complete failure.

• Expensive - because it needs extra hardware

Ring

A ring network is a local area network (LAN) in which the computers (workstations or other devices) are connected in a closed loop configuration. Adjacent pairs of nodes are directly connected. Other pairs of nodes are indirectly connected, the data passing through one or more intermediate nodes. The image below shows a ring network.

Advantages of a Ring Network:

• A Ring is relatively easy to install

• Cheaper - because less cables are needed

Disadvantage of a Ring Network:

• A break in a cable - will affect the whole network

Conclusion

Computer network is a group of two or more computer systems linked together to share information and hardware.

There are five different types of network, which are Local-area networks (LANs), Wide-area networks (WANs), Campus-area networks (CANs), Metropolitan-area networks (MANs) and Home-area networks (HANs).

Network Topologies is also classify types of network. There are 3 main layout of Network Topologies, they are Bus, Star and Ring.

In connecting computers together to form a Network, the structure and layout of the computers and the cabling required to link them together must be taking into consideration. The pattern of computer nodes and the way they are interconnected is referred to as the Topology.

Reference:

Here are the sources we used to find the information we needed.

* John Wobus (1994) , Local Area Networks, http://web.syr.edu/~jmwobus/lans/ (accessed 27th November 2003)

* No author, Media and Topologies part 1, http://studynotes.net/net1.htm (accessed 5th December 2003)

* No author, TekMom's Tech Buzzwords for Students, http://www.tekmom.com/buzzwords/zdnetwork.html (accessed 11th December 2003)

* No author, Network, http://www.webopedia.com/TERM/N/network.html (accessed 13th December 2003)

* No author, Token Ring, http://homepages.uel.ac.uk/u0110214/TokenRing.htm (accessed 14th December 2003)

CI1140 Omar Ahmed Suleiman K0309569

David Adisa K0309548

1