A new QoS-driven packet discarding scheme

The need to satisfy quality of service (QoS) requirements for individual connections is one of the major current challenges for ATM technology. In this paper we propose a new packet/frame discarding algorithm which makes use of virtual per-VC queueing. Mang and Levy (see Performance Modelling and Evaluation of ATM Networks, vol.IV, Chapman and Hall, London, 1998) proposed a cell-level scheme, the fair cell discarding (FCD) algorithm, and proved some fundamental properties that relate actual performance to the requirements. With FCD, cells are discarded according to a fairness criterion. The fairness criterion is defined by connections' mean arrival rates and their QoS CLR (cell loss ratio) requirements. As an extension of FCD, in this paper, we address packet-level integrity and introduce a new packet discarding policy CPD (complete packet discard) as well as a fair packet discarding (FPD) algorithm. With CPD, in case of buffer overflow, entire packets are discarded including cells in the buffer and new arrivals. Simulation results demonstrate the effectiveness as well as the limitations of the scheme.