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Topology. What are the consequences of using fewer than n 2 connections? Fewer interconnects make it practically feasible Contention likely – lower bisection bandwidth Other Topologies & worst case distances Token Ring – N (N is no of nodes) 2D torus - N Fat tree – 2logN 2D meshes 2N
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Topology • What are the consequences of using fewer than n2 connections? • Fewer interconnects make it practically feasible • Contention likely – lower bisection bandwidth • Other Topologies & worst case distances • Token Ring – N (N is no of nodes) • 2D torus - N • Fat tree – 2logN • 2D meshes 2N • Hypercube – Log(N/2) • Routing • Usually a random choice from no of equally good paths • Store-and forward vs. cut-through & wormhole forwarding
MPP, LAN, WAN • Compare and contrast the features. • MPP • Networks specifically designed, no standards • Use more novel and regular topologies • Smaller distances, high bandwidth and low overheads • Eg. CM-5 • LAN • Based on standards • Haphazard topologies evolved over years • Longer distance, emphasis on fault tolerance, large overheads • Eg. Ethernet • WAN • Based on standards • Simpler topologies than MPP • Very long distances, fault tolerant, large overheads • Eg. ATM