| Network Topologies | ||
| The topology of a network is the way in which the connections of a network are arranged. | ||
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There are a number of different network topologies but in reality most
networks are a combination of these.
The basic topologies are :
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Bus network
The nodes of the network (workstations, printers, other devices) are each connected to a bus - a cable down which data can be sent. The bus has terminators on each end. |
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A file server is the computer on the
network that stores the files used by other workstations. Eg. A large database
may be stored on the file server.
A printer may be connected to the bus, or to one of the workstations (printer server). The bus cable carries a transmitted message along the cable. As the message arrives at each workstation, the workstation computer checks the destination address contained in the message to see if it matches it's own. If the address does not match, the workstation does nothing more. If the workstation address matches that contained in the message, the workstation processes the message A simple network with less cabling than others. Poor reliability - if the bus has problems, the whole network will be unusable. The speed of the network will be slow if there are a large number of nodes. |
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Star Network
Each node of the network is connected to a central node, which may be a computer (file server) or a hub.
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Better reliability - If one cable
has a problem, the remaining nodes will continue to operate.
Good security of data - all data is controlled by the central node (file server) and does not have to pass through nodes other than transmitting and receiving node. It is easy to add new nodes. |
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Ring Network
The nodes are connected in a ring. Data is transmitted around the ring, being passed from one node to the next until it arrives at its destination. Data generally only flows in one direction. In a token ring network, a node wanting to transmit data waits for a 'token' to come round. The data is attached to this token and sent round the ring. Each node checks the token to see if it is for them. The receiving node downloads the data. |
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Good reliability - cable failures
can be easily isolated. Faulty workstations can be by-passed.
Security issues - data passes through a number of nodes when going from transmitting node to receiving node. Cabling can be costly. |
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