The features, architectures, and principles of key media access control (MAC) schemes for high-speed LAN and MAN systems are categorized and reviewed. These architectures are related to the hierarchical structure of a telecommunications network. An overview is given of the MAC protocol operation of key local- and metropolitan-area network systems, as defined by standards committees, covering current methods as well as approaches for future broadband integrated services digital networks. Modeling and analysis techniques are then reviewed for key classes of relevant MAC schemes, including fixed-assignment time-division-multiaccess (TDMA) schemes; demand-assignment reservation schemes, involving, in particular, pure packet-switched, pure circuit-switched and hybrid-switched integrated-services demand-assignment TDMA and time-division-multiplexing structures; demand-assigned polling procedures; and random-access policies.>

This paper derives exact results for a polling system such as a token bus or token ring with exhaustive service and priority polling. The results can also be used to analyze a terminal controller with a generalservice order table. There areNstations in the system and the token is passed among them according to a polling table of lengthM (\geq N). Stations are given higher priority by being listed more frequently in the polling table. By a straightforward extension of results of Ferguson and Aminetzah [5] for systems with circular polling and exhaustive service, it is shown that in general, theNmean waiting times require the solution of a set ofM - Nsimultaneous equations and a set ofM(M - 1)simultaneous equations. We show that partial symmetry in the polling table and the station characteristics can be used to significantly reduce the number of equations which must be solved. We present the reduced equation set for a two-priority class system and apply the results to a large token-passing bus network in which a few nodes account for a substantial portion of the network traffic. We show that in the latter case, the overall_ average message waitmg time can be significantly reduced by using priority polling: average waiting times at the high-priority nodes have large reductions in return for a smaller increase at low-priority nodes.

We consider a multiple-access broadcast communication channel which serves a network of terminals, each characterized by a distinct priority level. Higher priority terminals require, on the average, faster access across the communication channel than lower priority ones. We present a terminal priority contentionless access (TPCA) control scheme for sharing such a channel on a conflict-free basis. A ready terminal wishing to access the channel will wait for the channel to become idle, and then defer its access untill after higher priority terminals are given the opportunity to transmit. The model accounts for acquisition delays (including propagation and timearound delay components), idle detection times, multipacket message structures and different arrival intensities at different terminals, Analytical results are derived for the moments and transform of the message waiting-time distribution at each network terminal by relating the waiting times in our model to those in an appropriateM/G/1queue with HOL (head of the line) priorities. Performance curves are presented under varirous system parameter conditions which correspond to applications involving digital radio local distribution systems and metropolitan-area, packet radio, and local-area communicatiton networks.