Dynamic Rate-based Virtual Clock Scheduler for Output Buffered IP Switches

S. Shamala, M. Othman, R. Johari, and M.Y. Saman (Malaysia)


Scheduling algorithms, reservation algorithms, discrete-event simulation


- In this paper, an enhanced and improved version of the rate-based Virtual Clock scheduling algorithm is proposed and analyzed. The Virtual Clock scheduling tag constituting of the firewall and inverse bandwidth tag implements static bandwidth paradigm. However, the migration towards robust and adaptive network applications have complemented with dynamic resource reservation schemes are becoming dominant as the communication community increases. Thus, an enhancement of the Virtual Clock algorithm to sustain dynamic conditions is proposed in this research. An acceleration concept in contexts of congestion prevention is implemented in the proposed scheduler. The proposed enhanced Virtual Clock scheme aims at fulfilling the requested level of Quality of Service (QoS) while simultaneously achieving high resource utilization via a versatile and dynamic resource reservation scheme. An enhanced scheduling tag is implemented in the research. The tag computation integrates an correlation index between utilization and the sustained average delay. The results obtained through the extensive discrete-event simulation models have shown that the enhanced scheme has significantly improved the average delay, average buffer utilization and for different traffic patterns. The proposed scheme can be adopted for adaptive real-time traffic based applications to enhance the QoS in terms of better delay and improved resource utilization.

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