BOUNDS FOR PERFORMANCE-MEASURES OF TOKEN RINGS

In polling systems that have been studied in the literature, one usual ly asserts independent Poisson arrivals. This assumption is, however, unrealistic when dealing with many applications, e.g., local area netw orks (LAN's) using token-ring protocols. The arrival processes there m ay be quite irregular, highly bursty, and correlated. We use the new a pproach for modeling such arrival streams proposed by Cruz [8], [9], t o obtain strict upper bounds on several performance measures, It is ba sed on characterizing the inputs by bounds on the average arrival rate and the burstiness, and is especially useful in order to describe arr ival streams that are filtered (policed) by leaky buckets, We first ob tain bounds for the gated, exhaustive, and globally-gated service disc iplines, and then consider timed token rings (such as the FDDI), The r esults for the first three disciplines improve the general bounds obta ined in [4] and [5]. We further obtain improved exponential bounds of the type introduced by Chang [7], and Yaron and Sidi [17], for the glo bally-gated discipline.