Fair scheduling algorithms for QoS guarantees in high-speed networks

Abstract

B-ISDN are required to support a variety of services such as audio, data, and video, etc., so that the guarantee of Quality-of-Service (QoS) has become an increasingly important problem. An effective fair scheduling algorithm enables high-speed intermediate nodes to distribute link bandwidth fairly among competing connections. Therefore, it helps networks to guarantee the QoS requirements of connections. Generally, fair scheduling algorithms meets requirements of both the high performance and the easy implementation. In this thesis, we propose and analyze high-performance simple fair scheduling algorithms. The one is called "Virtual-Time-based Round Robin(VTRR)." This scheme maps the priorities of packets into classes and provides service to the first non-empty class in each round, and it uses and estimation method of the virtual time necessary to this service discipline. To find the first non-empty class, VTRR adopts a priority queueing system using a bitvector which decreases the number of instructions which need to be carried out in one packet transmission time segment. These policies help VTRR implementation in software, which presents flexibility for upgrades. Our analysis has demonstrated that VTRR provides bounded unfairness and its performance is close to that of Weighted Fair Queuing. Therefore, VTRR has a good performance as well as simplicity, so that it is suitable for B-ISDN. And, we propose and analyze the preemptive and nonpreemptive rate-based schedulers fir ABR service in the ATM network which ETRI is now developing. Since the switching network of this ATM network has no separate buffer for each class, TCB (Traffic Control Block) was adopted. This equips separate buffers in which the traffic scheduler operates. The proposed schedulers are non-work-conserving so as not to generate bursty ABR traffic. The preemptive scheduler saves cells in sorting bin keeping the transmission interval corresponding to the transmission rate. If a conflict occur...