The optimal joint sequence design in the feedback-based two-stage switch

The feedback-based two-stage switch is scalable as it is configured by a predetermined and periodic joint sequence of configurations [1]. Its major problem is that the average packet delay is high under light traffic load. In this paper, we improve the performance of feedback-based switch while still ensuring in-order packet delivery and close to 100% throughput. We first show that the different sequences of configurations may endow a feedback-based switch with different delay performance. We propose to devise a tailor-made sequence of configurations for the estimated traffic pattern. The optimal joint sequences that can produce the lowest average packet delay is formulated as an ILP (Integer Linear Programming) problem. The simulation results demonstrate that the optimal joint sequence can cut down the average packet delay up to 50%. Even under random uniform traffic, 14% performance improvement can be obtained. Last but not least, we also design a fast suboptimal algorithm for the practical implementation.