Steady State Analysis of the Rate Based Congestion Control Mechanism for ABR Services in ATM Networks

In ATM network environments congestion control plays an important role to support dif ferent quality of service guarantees for a large variety of tra c types While for real time communications like CBR and VBR services a preventive open loop congestion control mechanism is applied a reactive closed loop mechanism has been suggested for the ABR service class which was introduced mainly for data communications This paper presents an analysis to evaluate the performance of the rate based congestion control mechanism developed by the ATM Forum We derive formulae to compute the evolution of the allowed cell rate and the resulting bu er content during steady state Therefore we focus on tra c scenarios consisting of single sources as well as of homoge neous mixes of ABR sources From numerical examples we can conclude that an appropriate setting of the control parameters is important to achieve a reasonable performance of the rate based control mechanism especially to obtain low bu er requirements in conjunction with a high utili zation of network resources Furthermore a strong dependence on the number of active connections is observed