In a star connected interconnection network all the processor in the network are connected with single processor and this single processor acts as the central processor therefore routing of information between processors becomes a single processor (central processor) interrupt path. The diameter of star connected interconnection network is two (D = 2). Moreover the degree of the star connected interconnection network is ‘p-1’ having ‘p’ processor and the number of its communication links is ‘p-1’. The star connected interconnection network is similar to bus based interconnection networks. Unlike bus interconnection network, processor were connected to a central cable, here all the processors in the network are connected to a central processor with a point-to-point connection. Communication between any pair of processors is routed through the central processor, just as the shared bus forms the medium for all communication in a bus-based network. In star interconnection network, central processor acts as the bottleneck of network.
Star connected interconnection networks Characteristics:
- Star connection network consist ‘p-1’ communication links over ‘p’ processors in the networks.
- All the processors are connected to central processor with a point-to-point connection.
- Processors are sending and receiving information just single mediator i.e. central processor.
- Central processors acts as the connection builder or repeater as the external resources added there.
Example of Star Connected Interconnection networks:
The above star connected interconnection network having N=9 nodes and/or processor.
A total of communication links required by the network are =( N-1)
= (9-1)
= 8
Total 8 links are required in order to satisfy the star connected inter connectivity of the network.
Star Connected Interconnection networks Advantages:
- As compared to Bus networks star networks gives far much better performance, don’t necessarily to traverse information to all the processors in the networks. Transmitted information reaches the intended destination after passing through no more than 3-4 devices and 2-3 communication links. Performance of the network is dependent on the capacity of centralized processor.
- New processors easily connected without affecting rest of the processors in the network. Similarly processors can also be removed easily.
- Centralized management. It helps in monitoring the network.
- Failure of one processor or communication link doesn’t affect the rest processors in the network.
- Information are sent quickly as they don’t have to travel through any unnecessary nodes.
Star Connected Interconnection networks Disadvantages:
- Too much dependency on central processor has its own drawbacks. If central processor fails whole network goes down.
- Performance and as well number of processor which can be added in such interconnection network is depended on capacity of central device.
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