Fair explicit rate indication for ABR service in ATM networks

Abstract

Available Bit Rate (ABR) service is designed to support data applications, such as TCP/IP, over Asynchronous Transfer Mode (ATM) networks. A proper flow control scheme which can achieve the goals of congestion avoidance and fairness is essential to the provision of the Quality of Service (QoS) in ATM ABR service. This thesis focuses on the development of fair explicit rate indication algorithms which can best meet the goals of ABR flow control. To start with, two explicit rate allocation algorithms for max-min fairness are developed based upon two existing algorithms devised by Kalampoukas and Charny respectively. The improvements include the avoidance of the non-comforming use of the Current Cell Rate (CCR) field in Resource Management (RM) cells and better capability to avoid congestion. The principles of the two improved algorithms are further extended to achieve other fairness, such as generalised max-min (GMM) fairness, weighted fairness and generic weight-proportional max-min (GWPMM) fairness etc. A new fairness criterion, the extended weighted (EXW) fairness, is proposed in the thesis to meet the QoS requirements of the ABR applications. One advantage of the EXW fairness is that the explicit rate indication algorithms for EXW can be easily adapted to achieve all the existing fairness. This simplifies the design and implementation of a flow control mechanism in an ATM switch. By proposing a general fairness definition, F-fairness, the general principle regarding fair rate allocation, such as its formulation, centralised rate allocation process, bottleneck structure and distributed rate allocation algorithm, is presented. This general principle provides a theoretical base for the study on the fair rate allocation in ABR service. In the thesis, two new fair flow control schemes are proposed as well. One is fair flow control by per-VC virtual queueing. The other is fair explicit rate indication by per-VC virtual fluid control. The flow control with per-VC virtual queueing maintains the advantages of the flow control with per-VC queueing. such as the achievement of fairness, while avoiding its drawbacks, such as the complicated per-VC buffer management. The explicit rate indication by per-VC virtual fluid control extends the principle of the control scheme with per-VC virtual queueing and overcomes some of its limitations. For all the explicit rate indication algorithms developed in the thesis, simulation is carried out to evaluate their performance. The results show that they control network congestion effectively and achieve the desired fair rate allocation accurately. The work in this thesis is fundamental to ATM ABR service.