The evolution of distributed computing is being simultaneously influenced by the new multimedia applications requirements and by the increasing capability of high-speed multiservice networks. The performance of the communications system will be critical in meeting the needs of the emerging distributed multimedia applications; in particular new transport mechanisms should guarantee quality of service for a wide variety of end user systems. Specification and design of a high performance transport service and protocol should be based on a top down approach. This paper describes the key communications requirements as a first stage in establishing an integrated Quality of Service Architecture (QOS-A) for distributed multimedia computing.