Delay Impact of Bursty Cross Traffic in Combined Input and Output Queued Switches Using Virtual Input Queueing Under Diverse Network and Traffic Conditions

Abstract

The rapid advancement of digital transformation (DX) requires networks to concurrently support diverse traffic types on a shared infrastructure. Next-generation infrastructures, such as the innovative optical and wireless network (IOWN) and high-speed data centers, require the coexistence of flows with disparate requirements. Here, low-delay critical communications (e.g., real-time control) must function alongside high-volume non-critical communications (e.g., background file transfers). While traffic shaping can effectively suppress the burstiness of critical flows, concurrent non-critical flows often exhibit significant temporal burstiness. In basic combined input and output queued (CIOQ) switches, such bursty flows can monopolize output FIFO buffers, causing significant delay degradation for critical flows. To mitigate this interference, this paper investigates a virtual input queue (VIQ) scheme, which provides logical isolation at the output stage. We evaluate its performance across diverse conditions via discrete-time simulations. Simulation results show that the CIOQ switch with VIQs effectively isolates critical flow from the impact of bursty flow originating from other input ports, thereby mitigating delay degradation caused by cross-port interference under the examined traffic conditions. They also reveal how the burstiness of non-critical flows, the number of switch ports, arrival rates, and traffic uniformity influence the performance.