1. Network Topologies

2. What is a Network?
A computer network is a set of computers connected together for the purpose of sharing resources. The most common resource shared today is connection to the Internet. Other shared resources can include a printer or a file server.

3. Network Advantages Disadvantages
Sharing devices such as printers saves money.
Site (software) licences are likely to be cheaper than buying several standalone licences.
Files can easily be shared between users.
Network users can communicate by   and instant messenger.
Security is good - users cannot see other users' files unlike on stand-alone machines.
Data is easy to backup as all the data is stored on the file server.
Disadvantages
Purchasing the network cabling and file servers can be expensive.
Managing a large network is complicated, requires training and a network manager usually needs to be employed.
If the file server breaks down the files on the file server become inaccessible. might still work if it is on a separate server. The computers can still be used but are isolated.
Viruses can spread to other computers throughout a computer network.
There is a danger of hacking, particularly with wide area networks. Security procedures are needed to prevent such abuse, eg a firewall.

4. Bus
A bus network is a network topology in which nodes are directly connected to a common linear (or branched) half-duplex link called a bus.

5. Bus Advantages Disadvantages
Easy to connect a computer or peripheral to a linear bus
Requires less cable length than a star topology resulting in lower costs
It works well for small networks.
Easy to Extend
Disadvantages
Entire network shuts down if there is a break in the main cable
Terminators are required at both ends of the backbone cable
Difficult to identify the problem if the entire network shuts down
Not meant to be used as a stand-alone solution in a large building
It is slow when more devices are added into the network
If a main cable is damaged then network will fail or be split into two networks
It is difficult to detect trouble at an individual station.

6. Ring
A ring network is a network topology in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node - a ring. Data travel from node to node, with each node along the way handling every packet.

7. Ring Advantages Disadvantages
Very orderly network where every device has access to the token and the opportunity to transmit
Performs better than a bus topology under heavy network load
Does not require a central node to manage the connectivity between the computers
Due to the point to point line configuration of devices with a device on either side (each device is connected to its immediate neighbour), it is quite easy to install and reconfigure since adding or removing a device requires moving just two connections.
Point to point line configuration makes it easy to identify and isolate faults.
Reconfiguration for line faults of bidirectional rings can be very fast, as switching happens at a high level, and thus the traffic does not require individual rerouting
Disadvantages
One malfunctioning workstation can create problems for the entire network. This can be solved by using a dual ring or a switch that closes off the break.
Moving, adding and changing the devices can affect the network
Communication delay is directly proportional to number of nodes in the network
Bandwidth is shared on all links between devices
More difficult to configure than a Star: node adjunction = Ring shutdown and reconfiguration

8. Star
Star networks are one of the most common computer network topologies. In its simplest form, a star network consists of one central switch, hub or computer, which acts as a conduit to transmit messages.

9. Star
Advantages
Star networks are very reliable because if one computer or its connection breaks it doesn’t affect the other computers and their connections
Disadvantages
An expensive network layout to install because of the amount of cables needed
If the server crashes or stops working then no computers will be able to access the network

10. By Daniel Hillier