Thursday, February 5, 2009

Topologies

Topologies
Topology is a way for arranging a number of systems such that they provide a better communication and response among each other.
Bus Topology –
A bus topology connects each computer to a signal cable segment.
At each end of the cable there is a terminator. On a bus network, if the connection to one station comes loose, or if a cable breaks, the entire cable segment loses its connectivity.
Local bus network
A regular bus network uses drop cables and external transceivers to connect each station to the main “backbone” cable.
Drop cables are connected to AUI connectors on the network adapter at one end, and the other end is connected to an external transceiver that attaches to the main backbone cable.
Regular bus network
Star topology –
A special unit called a hub is used in a network using a star configuration. The hub provides a common connection so that all of the workstations can communicate with one another.
By using a hub you can centralize network management. However if the hub fails, the network fails.
A star topology uses signal splitters in the hub to send out signals in different directions on the cable connections.
Both active and passive hub can send a stronger signal to feed a longer cable and more signal splitters.
Ring Topology -
On a ring network, stations are situated on a continuous network ring on which a token is passed from one station to the next.
A station must wait for a free token in order to transmit data.
When there is a cable failure on a ring network only a small number of stations are affected.
Additional station can be added to a ring network without a server drop in performance.

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