Title: Markovian Analysis of DQDB MAC Protocol


Authors: Falko Bause, Pieter S. Kritzinger, Michael Sczittnick




The Distributed Queue Dual Bus (DQDB) protocol is

currently under study as the proposed standard for Metropolitan

Area Networks (MAN).  This paper describes the steady state

performance analysis of a DQDB network by means of Markovian

modelling. In the analysis each station is considered

independently, but not in isolation, thus avoiding the

computational complexity which would otherwise be introduced by a

large number of stations. Thus the restriction to trivially small

networks frequently found in other analytical models does not

apply in our case.  The model takes into account the relative

position of a station on the network, the phase difference between

the two buses as well as the relative availability of QA-slots.

Comparisons with our own simulation studies show that the

analytical results lie well within the 90 percent confidence

interval.  The effect of various model parameters on network

performance are also studied.


Published in:

        South African Computer Journal (SACJ), Vol. 11, 1994.