Strathnet—a local area network

The paper outlines the design and implementation of Strathnet, a local area network in the Department of Computer Science at Strathclyde University in Scotland. Strathnet is based on the Ethernet system, and will be used for experimental work on local network architectures, particularly in comparison with a Ring system, before eventually providing a network service within the department

Terminal concentrator for an Ethernet-style local network

The design and implementation of a terminal concentrator for the Strathnet local area network is described. Strathnet is an Ethernet-style local network in which all devices are connected to the network coaxial cable by means of microprocessor-based access units. The network protocols (in both hardware and software) are implemented in a layered fashion along the lines of the International Standards Organization open systems interconnection reference model. The terminal concentrator is an access unit with up to seven ports for terminal connection, a Strathnet port implementing carrier sense multiple access with collision detection hardware and all the necessary software layers. Although the lowest layers are dependent upon the Ethernet-style hardware, the intermediate software implements the basic block and byte stream protocols more commonly found in Cambridge ring networks, and the concentrator software at the highest level provides the user with a Unix-like interface. A major aim has been to implement Cambridge ring software protocols over Strathnet hardware

Building local area networks to Ethernet specification

Digital, Intel and Xerox (DIX) have published an Ethernet standard that specifies the physical and datalink layers of Ethernet, one of the two types of local area networks likely to be widely used in industrial and commerical applications. The publication of the DIX specification is a commercial exercise intended to encourage the implementation and marketing of Ethernet-compatible network elements. In the Computer Science Department at Strathclyde University the authors followed this specification to some extent in implementing an Ethernet-style local network called Strathnet. In their implementation, the physical and datalink layers are built into microprocessor-based network-access units by means of which computers, terminals and other devices are connected to Strathnet. The paper discusses the feasibility and desirability of building local networks to the standards of the Ethernet specification and in the light of this discussion outlines the author's approach in the implementation of Strathnet

A gateway for linking local area networks and X.25 networks

This paper describes the hardware and software architecture of a gateway between an Ethernet-style local area network called Strathnet and an X.25 packet switched network (British Telecom's PSS). The hardware is based on a Motorola 68000 processor using the VME bus, and peripheral boards based on an 8-bit 68120/1 processor for the local network and the X.25 interfaces. The software is layered from the low-level executive, through the three X.25 levels and the transport layer, and through the corresponding layers on the local network side, to the bridging software itself. Both hardware and software are designed so that the system can be a general-purpose gateway: for example, the local area network peripheral board could be replaced by a ring type interface, and the software within the local network layers could similarly be replaced

Interfacing PDP-11 and LSI-11 computers to local area networks

At Strathclyde University we have a dual local area network configuration consisting of a commercial Cambridge Ring and an Ethernet-style network called Strathnet designed and built in the Department of Computer Science. The majority of the hosts in our dual configuration are PDP-11 and LSI-11 computers. With these networks we are investigating the comparative performances of each and investigating the architectures and protocols of local networks in general. One of our chief interests is in designing "access units" by means of which computers, terminals and other devices are interfaced to local network communication media. In this paper our dual network configuration is outlined, our approach to building a general-purpose network access unit is explained and a description is given of how we at present interface the PDP-11 and LSI-11 computers to both networks