The IBM Enhanced Clustered Fortran (ECF) advanced technology project combines parallel computing technology with a HiPPI-based LAN network. The ECF environment is a clustered, parallel computing environment which consists of IBM ES/90001 complexes and possibly other parallel machines connected by HiPPI. The ECF software, including the language processor, is independent of hardware architectures, operating systems, and the Fortran compiler and runtime library. The ECF software is highly portable because it is based on well-known, standard technology and transport protocols such as Remote Procedure Call (RPC), X/Open Transport Interface (XTI), and TCP/IP. The ECF software is transport-independent, and can accommodate other transport protocols concurrently. This paper describes the IBM ECF environment including the language extensions, the programming model, and the software layers and components. Also, this paper explains how to achieve portability and scalability. Lastly, this paper describes how effective task communication is accomplished in ECF through RPC, XTI, TCP/IP, and a customized enhancement over HiPPI. An analysis of network performance in terms of bottleneck conditions is presented, and empirical data indicating improved throughput is provided. Comparisons to alternative methodologies and technologies are also presented.