Design and performance analysis of the generalized timed token service discipline

Multiservice networks host heterogeneous applications, requiring different qualities of service (QoS), the coexistence of which can be efficiently accounted by employing scheduling algorithms which are capable of providing different QoS simultaneously. In a previous work, we defined a reference dual-class (DC) paradigm, according to which rate-guaranteed flows are restrained from using more than their minimum guaranteed rate in the presence of backlogged best-effort flows and the latter share all the remaining capacity according to predetermined weights. The timed token service discipline (TTSD), which applies at the output link of a switch the same rules used to control medium access by the timed token protocol, was also introduced and analyzed therein. It was proven that TTSD shares most of the capacity which is not strictly needed by the rate-guaranteed flows among the best-effort ones, thus achieving one of the goals of the DC paradigm. However, in TTSD, best-effort flows can only share the available capacity equally. We take into account the issue of differentiating the capacity sharing among the best-effort flows: We define a generalized TTSD (GTTSD) in which the latter actually share capacity according to predefined weights in a weighted fair queuing service discipline. Formal analysis and simulation results show that GTTSD closely approximates the DC paradigm.