Weighted fair blocking mechanisms for discrete-time multiplexing

A major challenge in integrated services packet networks is the design of packet multiplexing systems to support different QoS requirements. We focus on the problem of satisfying different loss requirements. In time-slotted multiplexing systems, one may have batch arrivals (i.e., simultaneous arrivals in a time slot), and it is necessary to reject some of the packets in a batch when there is an insufficient number of available buffers. We propose a simple and intelligent probabilistic mechanism for rejecting packets in order to meet the loss requirements. It may be used as a selective discard mechanism to provide different QoS levels in terms of loss (weighted fair blocking). It may also be used to achieve fairness (balanced fair blocking). It offers important advantages and gains relative to existing approaches while being very simple. It allows decoupling of buffer dimensioning from the parameterization of a discard mechanism. It is universal in the sense that it may be used on top of many discrete-time multiplexing schemes. It also reduces the buffer space needed to meet loss requirements compared to natural rejection methods such as random selection. The mechanism is derived explicitly for two Markov modulated Bernoulli sources. The derivation for an arbitrary number of Bernoulli sources is formulated as a linear programming problem.