TOPOLGOIES

TOPOLGOIES

1. bus

   • a bus network has a single backbone cable and all the devices are attached to it
   • when a message is sent, it is divided into chunks and sent in both directions along the cable.
     • the signal passes along the cable in both directions until it weakens or is absorbed
   • all the computers on the network recieve it however onlly the one addressed accepts it
   • On the bus network, all the computers share the medium.
   • Only one computer can transmit at a time.
     • they have to wait if the network is busy
     • with enough users, the wait can make the network unusable
   • Bounces
     • if the signal reaches the end of the cable, it bounces back
     • Bounces can also affect the performance of a network, because they add enormously to the traffic and cause data collisions
     • If the cable breaks, there will be bouncing from the broken end and the network breaks down.
   • Bus networks are very simple to set up
     • But they are only suitable for very small network installations

2. Ring

   • The devices are arranged in a circle.
     • Each computer is responsible for passing the message on
     • One way to implement a ring network is by token passing
       • With this, a packet called a token passes from one computer to the next
         • If a computer has data to send, it modifies it
           • When received at the intended destination, the receiving device sends a message back to the sender acknowledging safe delivery
   • A ring topology guarantees that a computer can send a message because there is no need to wait

3. Star

   • Most common way to set up a network
   • All connections are to a central device such as a writing cabinet with switches
   • Installation of a star network is labour intensive as the cable often has to go through calls ceilings or under floors
   • It is a skilled job to wire up the cabinets and all the connecting leads
     • but, the network performance is faster than a bus
   • If one part of the network is damaged, it does not necessarily affect the entire network

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