Design of a Real-Time Switch with Bounded Delays
Kyungtae Kang, Lui Sha · Illinois Digital Environment for Access to Learning and Scholarship (University of Illinois at Urbana-Champaign) · 2010
Most network switches are designed for best-effort transmission of Internet traffic. Relevant studies have focused on maximizing throughput and minimizing delay in an average sense, but this is not suitable for hard real-time applications, in which guaranteeing delay bound is critical. We propose a real-time switch design, based on a crossbar switching fabric, which combines clearance-time-optimal switching with clock-based scheduling, and we show that any feasible traffic is guaranteed to be switched in two clock periods. The concept of one-shot traffic allows delay to be bounded without a requirement for traffic periodicity, at the cost of a fixed delay of one clock period. The proposed switch uses real-time virtual machine tasks to serve traffic, which simplifies analysis and provides isolation from other system perations. Simulations show that our real-time switch achieves a larger schedulability region and a bounded lower end-to-end delay with a shorter clearance time than iSLIP, which is one of the most widely used crossbar switch schedulers.