Clusters of workstations/PCs connected by o?-the-shelf networks have become popular as platforms for cost-e?ective parallel computing. Technological - vances in both hardware and software have made such a network-based parallel computingplatform an a?ordable alternative to commercial supercomputers for an increasing number of scienti?c applications. Continuing in the tradition of the three previously successful workshops, this fourth Workshop on Communication, Architecture and Applications for Network-basedParallelComputing(CANPC 2000)broughttogetherresearchers and practitioners working in architecture, system software, applications, and performance evaluation to discuss state-of-the-art solutions for network-based parallel computing. This year, the workshop was held in conjunction with the sixth International Symposium on High-Performance Computer Architecture (HPCA-6). As in prior editions, the papers presented here are representative of a sp- trum of research e?orts from groups in academia and industry to further - prove cluster computing¿s viability, performance, cost-e?ectiveness, and usab- ity. Speci?cally, we have arranged the contributions in this edition into four groups: (1) program development and execution support, (2) network router - chitecture, (3) system support for communication abstractions, and (4) network software and interface architecture.

Program Development and Execution Support.- REXEC: A Decentralized, Secure Remote Execution Environment for Clusters.- A Visual BSP Programming Environment for Distributed Computing.- Transparent Network Connectivity in Dynamic Cluster Environments.- Network Router Architecture.- A New Methodology to Compute Deadlock-Free Routing Tables for Irregular Networks.- On the Performance of Up*/Down* Routing.- Extending Dynamic Reconfiguration to NOWs with Adaptive Routing.- System Support for Communication Abstractions.- MPI Derived Data Types Support in VIRTUS.- Fast Collective Communication Algorithms for Reflective Memory Network Clusters.- Broadcast/Multicast over Myrinet Using NIC-Assisted Multidestination Messages.- Network Software and Interface Architecture.- Simulation Studies of Gigabit Ethernet Versus Myrinet Using Real Application Cores.- Comparison and Evaluation of Design Choices for Implementing the Virtual Interface Architecture (VIA).- Efficient Communication Using Message Prediction for Cluster of Multiprocessors.