Research On Queuing And Scheduling For CICQ Switches

Switching fabrics and scheduling policies are the core technologies of the routing and switching equipment, and their performance has direct effects and even determines the performance of the routing and switching equipment. With the fast development of information technology, Internet has undergone great changes in the overall scale and architecture in the last few years. Traditional switching and scheduling mechanisms have become the bottlenecks for further network developments.Combined with the research and development of the project "Research on system performance and key technologies of large-scale Access Convergence Router (ACR)" supported by the Major Dedicated Research Project of the High-performance Broadband Information Network under China National Research and Development Program 863 for the Tenth-Five-Year Plan in the information technology, this dissertation classifies and compares the current switching systems from the perspective of the general model of various switching systems, and summarizes results achieved in this area. Based on the new buffered crossbar switching unit, it comes up with researches into the extensibility and multicast supporting scheme in the high-speed environment, creating a suitable solution to the switching system for ACR. Its main work and contributions are outlined as follows:Due to the deficiency of theory analysis in switching technology and the lack of system-level support of the switching technology from simulation and experimental evaluation tools, a dedicated switching performance evaluation system (SPES) is designed and implemented by adopting system-level design methods and object-oriented technology. It has good extensibility and follow-on features and provides a basic research platform for technical innovation and scheme design of the switching technology.The dissertation analyzes the guideline for designing high extensible switching and scheduling algorithms. Based on this guideline, it focuses its research on the design of the scheduling policies for combined input and cross-point queuing switching fabric and comes up with FDR (Fair and Dynamic Round-robin) algorithm, whose complexity is only 0(1). It has excellent dynamic and extensibility. The simulation results of the SPES system show that the FDR algorithm exhibits good throughput, delay and anti-burst performance.In order to overcome the deficiency in supporting multicast in current switching systems, the dissertation proposes a new switching fabric MCICQ (Multicast supporting CICQ) which supports the uni-/multicast hybrid scheduling, and Scheduling policies MFDR and MFS which support the parallel distributed uni-/multicast are also proposed. With the fanout splitting mechanism, both MFDR and MFS can achieve good performance without speedup, and their complexity is only 0(1). MFS scheduling policy can also provide different bandwidth guarantees for uni-/multicast traffic. Simulation results under SPES show that both MFDR and MFS can achieve good performance.From the development requirements of the ACR router and oriented toward ACR features, such factors as systematic performance, designing cost and development cycle have been taken into account. A system solution has been provided herein for ACR to support multicast. It meets the requirements in extensibility and multicast supporting. Its engineering implementation scheme has been successfully applied to the actual development of routing and switching equipment under the project of ACR.