Dichotomy Slot Allocation: A QoS Guaranteed Scheduling Algorithm for Input-Queued Switches

With the rapid increase of real-time applications, jitter, delay, and throughput have become the three important QoS criteria in the scheduling of input-queued (IQ) switches with virtual output queues (VOQ). In this paper, we propose a novel frame-based scheduling algorithm, referred to as dichotomy slot allocation (DSA), to achieve high throughput, bounded delay, and bounded jitter. DSA possesses three major characteristics. First, DSA schedules the switch on a per-VOQ basis, and strives to provision QoS guarantees for each traffic stream corresponding to each VOQ. Second, DSA allocates the exact amount of slots to schedule the actual traffic of each VOQ, and decides the time slot for each packet. Third, DSA equally allocates the slots in a frame to each port pair, and then adjusts the scheduling to meet the actual traffic demand. The adjustment process employs a specially designed order named Dichotomy Order to guarantee QoS. Both analysis and simulation results demonstrate that DSA achieves good performance in jitter and throughput.