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 LAN WAN 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 Simpler topologies than MPP Very long distances, fault tolerant, large overheads Eg. ATM