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- 2. 2 Introduction Physical and LogicalTopologies Topologies Bus Ring Star Extended Star Mesh Hybrid
- 3. 3 Physical vs. LogicalTopology The actual layout of a network and its media is its Physical Topology The way in which the data access the medium and transmits packets is the Logical Topology A glance at a network is not always revealing. Cables emerging from a Hub does not make it necessarily a Star Topology – it may actually be a bus or a ring
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- 5. 5 Bus Topology (5) Advantages Inexpensiveto install Easy to add stations Use less cable than other topologies Works well for small networks Disadvantages No longer recommended Backbone breaks, whole network down Limited no of devices can be attached Difficult to isolate problems Sharing same cable slows response rates
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- 7. 7 Ring Topology (3) Advantages Datapackets travel at great speed No collisions Easier to fault find No terminators required Disadvantages Requires more cable than a bus A break in the ring will bring it down Not as common as the bus – less devices available
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- 9. 9 Star Topology (3) Advantages Easy to add devices as the network expands One cable failure does not bring down the entire network (resilience) Hub provides centralised management Easy to find device and cable problems Can be upgraded to faster speeds Lots of support as it is the most used Disadvantages A star network requires more cable than a ring or bus network Failure of the central hub can bring down the entire network Costs are higher (installation and equipment) than for most bus networks
- 10. 10 Extended Star Topology AStar Network which has been expanded to include an additional hub or hubs.
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- 12. 12 Mesh Topology (2) Notcommon on LANs Most often used in WANs to interconnect LANS Each node is connected to every other node Allows communication to continue in the event of a break in any one connection It is “Fault Tolerant”
- 13. CP2073 Networking 13 MeshTopology (3) Advantages Improves Fault Tolerance Disadvantages Expensive Difficult to install Difficult to manage Difficult to troubleshoot
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- 15. 15 Logical Bus •Modern Ethernetnetworks are Star Topologies (physically) •The Hub is at the centre, and defines a Star Topology •The Hub itself uses a Logical Bus Topology internally, to transmit data to all segments
- 16. 16 Logical Bus Advantages A singlenode failure does not bring the network down Most widely implemented topology Network can be added to or changed without affecting other stations Disadvantages Collisions can occur easily Only one device can access the network media at a time
- 17. 17 Logical Ring Data ina Star Topology can transmit data in a Ring The MAU (Multistation Access Unit) looks like an ordinary Hub, but data is passed internally using a logical ring It is superior to a Logical Bus Hub – see later slide
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- 19. 19 Logical Ring (3) Advantages Theamount of data that can be carried in a single message is greater than on a logical bus There are no collisions Disadvantages A broken ring will stop all transmissions A device must wait for an empty token to be able to transmit
- 20. 20 Summary Bus Topology Ring Topology StarTopology Other Topologies Logical Topologies Questions and Answers