Robert M. Metcalfe

Pup: An Internetwork Architecture

Pup is the name of an internet packet format (PARC Universal Packet), a hierarchy of protocols, and a style of internetwork communication. The fundamental abstraction is an end-to-end media-in dependent internetwork datagram. Higher levels of functionality are achieved by end-to-end protocols that are strictly a matter of agreement among the communicating end processes. This report explores important design issues, sets forth principles that have guided the Pup design, discusses the present implementation in moderate detail, and summarizes experience with an operational internetwork. This work serves as the basis for a functioning internetwork system that provides service to about 1000 computers, on 25 networks of 5 different types, using 20 internetwork gateways.

Fibernet: Multimode Optical Fibers for Local Computer Networks

Local computer networks which communicate over copper conductors have been developed both to promote resource sharing and provide increased performance. Such networks typically operate at bandwidth-length ( Bw \circ L ) products up to a few MHz \circ km . In this paper we consider the use of fiber optics in such networks, and give a status report on a star-configured fiber optic network experiment called Fibernet which operates at a Bw \circ L product of \sim 100 MHz\circ km at a data rate of 150 Mbits/s and which in its final phases will connect up to 19 stations. We compare the merits and problems of linear, ring and several star configurations, and of active versus passive networks. The packet communication protocol is discussed and network efficiency is calculated as a function of the packet length, channel capacity and network propagation time. We describe the system performance of the present Fibernet experiment, which uses a 19-port transmissive star coupler, GaAIAs injection lasers and avalanche photodiodes, and incorporates bi-phase data encoding. Power distribution inhomogeneities, observed in the output of the transmissive star couplers mixer rod, are explained geometric-optically.

A Specific Internetwork Architecture (Pup)

Research in network interconnection techniques has been motivated by the desire to permit communication among diverse, geographically distributed computing resources and users interconnected by a wide variety of network technologies.