This paper describes the design and operational experience of a low cost (less than $200 per port connection) local area network, MONET. The network was developed by the Computer Centre at Monash University, Australia over the past six years to provide access between a large number (2000 or more) of computers, terminals and other devices across the campus.

The network consists of a number of microprocessor-controlled communication units called “nodes” connected by a “bus.” Each node can connect to computer ports, terminals, and to other nodes by multiplexed communication links allowing MONET to form a large network. The implementation uses a 1.5 Mbit/sec twisted pair wire bus with “Carrier Sense Multiple-Access with Collison Detection” (CSMA/CD) protocol to resolve contention over the bus.

MONET provides CCITT V.24/V.28 data with modem controls, and data-only connections to terminals using RS-232C, RS-422 and 20mA current loop. At the design time, special attention was given to such issues as naming transparency, security of access, controlled allocation of resources through a network manager (NETMAN), and quick recovery of the network operation after power failures. The design effort of the MONET network began in 1978 when little experience with other LANs was available, and has been in operation since March 1982. The authors’ experience with the firmware implementation details, as well as with management of a large network in a computing environment with constant upgrade or changes of the network configuration and increasing user demands, will be a good practical guideline for the designers of a similar network. More interested readers may find detailed information in the MONET Technical Manual available upon request from Monash University Computer Centre, Clayton, Victoria 3168, Australia.