This paper is a concerned principally with the hardware technology of local networks. After a general introduction to the subject of local networks (note that local area networks are introduced later as a subset), Section 1 of the paper surveys the topologies and tansmission media that are currently appropriate for local networks and considers the relationship between them. The author observes that the choices of transmission medium and topology cannot be made independently, although some of the restrictions suggested are based on assumptions about available equipment rather than fundamental technological limitations. It is assumed, for instance, that the central switching element in a star topology network is a (relatively slow) circuit switch, and thus requires nothing etter than a twisted pair for its implementation. High-speed packet switched stars are quite feasible, however, and indeed a multiplicity of each switches can be interconnected by coaxial cable or optical fibre to form a tree (such networks have been constructed at the University of Manchester in the UK (Centrenet) and by American Bell [1]. In this paper the tree topology is assumed to be nothing more than the general case of a bus, with extended spurs as branches.

Three types of network are defined: Local Area Networks (LANs), High-Speed Local Networks (HSLNs) and computerized branch (i.e., telephone) exchanges. The remainder of the paper concentrates on the first two of these types, with Section 2 of the pape presenting a very thorough survey and comparison of LAN and HSLN networking techniques based on the bus topology.