Xerox Network Systems

Abstract: The Nestar Plan 4000 network was designed using the ISO Open Systems Interconnection model. The Xerox Network Systems Internet Transport Protocols (XNS) were chosen for the network and transport layers, a token-passing protocol (Arcnet) for the physical and datalink layers, and existing Nestar server software for the highest layers. The physical and datalink layers are supported by a VLSI chip and their implementation was straightforward. In spite of their detailed specification, implementing the network and transport layers presented some unanticipated challenges. This paper discusses details of our experience in implementing the network with emphasis on the problems encountered and how they were solved.

Abstract: This chapter describes the major characteristics of the Xerox Network Systems (XNS) architecture and relates it to the needs of end users that motivated its design. First, we will examine the basic design principles of XNS and compare its overall model of layers to that of the ISO Open Systems Interconnection (OSI) model. Within that model, we will move from the bottom layers up through the top layers—from the communications channel through support applications to the direct user applications.

Abstract: The Xerox Research Internet, which has been in operation within Xerox for over a decade now, is composed of some 200 geographically dispersed Ethernet local area networks [1,2]. Not all networks in the Internet, however, require the same degree of interconnectivity. In some cases information is exchanged only occasionally, and then in the form of mail messages. In order to support this type of interaction, in a cost effective manner, it is highly desirable to implement internetwork communication links using switched media.This paper describes an experimental facility, developed for the management of transient internetwork communication links. The major novelty lies in the idea of allowing high level application programs to dynamically alter the Internet topology, without end-users being involved, or even aware of what is happening.