- A user can access any software from any station.
- Data can be shared by all users at the same time. Many people can access or update the information held on a database at the same time. Thus information is up to date and accurate.
- Users can communicate with others on the network by sending messages and sharing files.
- Individual workstations do not need a printer; one high quality printer can now be shared by everyone, thus cutting costs.
- Networks provide security. A user must have the correct Password and User ID in order to be able to access the information on the network.
- Private areas on the network can be set up that allows each user to store their personal files. The only other person who can access these files is the 'system administrator' who looks after the network.
Disadvantages of Networks
- Networks can be expensive to set up. They often involve taking up floors and ceilings to lay hundreds of metres of cables.
- The File Server needs to be a powerful computer, which often means that it is expensive.
- Networks are vulnerable to security problems. Hackers, disgruntled employees or even competitors might try to break into the system to read or damage crucial information. Much effort is spent preventing unauthorised access to data and software.
- If the main File Server breaks down, then the whole system becomes useless and no-one can carry on working.
- Because networks are often complicated, they need expensive expert staff to look after them.
- As the number of users increase on the network, the performance of the system can be affected and things start to slow down.
Network Topologies.
Star, Bus and Ring
Star
Each workstation has its own direct line to the server. Connections to the server are made with hubs or switches.
Hubs connect many lines together.
Switches allow the network manager to connect certain workstations to specific servers.
Advantages
Good Security - no workstation can interact with another without going through the server first.
Reliable - if one connection fails, it does not affect others.
Disadvantage
Installation is an expert job.
Extra hardware required such as hubs, switches and wiring centres.
Ring
The workstations are attached to a cable arranged in a ring
Advantage
Very fast - all data traffic occurs in the same
direction so there should be no data collisions.
Disadvantage
If a single machine is switched off then the network does not work. If the cable breaks, once again, the network does not work.
Bus
This is the simplest way to connect workstations, servers and other components of a network by using a single cable. One or more of the workstations act as the File Server, whilst the other machines are used as workstations or terminals.
Advantage
Easy to install
Very cheap
Disadvantage
If many workstations are using the network at the same time, response can be very slow, thus frustrating users who want to work quickly. The technical term for data trying to travel simultaneously along the cable in different directions is called 'data collision'. A busy network will have many data collisions.
If there is a problem with the cable, the entire network stops working.