The reason for this constraint stems from the fact that firstly, we can experience significant communication problems between distant computers, and secondly it is not likely, at this stage, that we can use resources that are not within our institution. Technical Report IFI-TR 94.01. Department of Computer Science. CH-8057 Zurich, Switzerland. Communication between processing elements during the execution of a parallel application is a main bottleneck for all distributed memory systems and especially for clusters.
Applications is connected to n different network channels.
Based on a tree shaped logical interconnection topology,thePARC system provides a programming interface and tools for the administration of large WAN metacomputers with several hundred nodes. Expected Bandwidths and Latencies. Ethernet LANs can connect as muchas255 workstations, but an average LAN comprises about 20 machines. However, a utilization of more than 20 is already considered as a high load. Ethernet s CSMA CD protocol will then suffer many collisions, thereby further reducing the maximum attainable throughput.