Design And Analysis Of High-Radix Router Based On Multi-Stage Switching Fabric

High performance interconnect is an important part in computer system,it is of great significance for performance improvement and expansion of the whole system to design interconnects with low latency,high throughput,high scalability and low cost.The computing ability of processing nodes and the off-chip bandwidth increase rapidly with the development of microprocessor technology.Building large-scale interconnection networks with high-radix routers can get better performance and scalability compared with traditional low-radix structures.A simple expansion of the number of crossbar will make wire resources inside the router grow rapidly and make the implementation cost unbearable,therefore it is necessary to design new switching fabrics.Hierarchical structures like YARC are once the design mainstream of high-radix routers,however these structures require too many buffers and wires,thus they are hard to expand well.The “network within a network” method can reduce the wiring density and is conducive to expand.To address the above-mentioned problems,high-radix router mainly use multi-stage switching fabrics in this thesis,which will focus on the following three aspects:The development of high performance interconnects and high-radix routers is analyzed deeply,and then traditional design methods for high-radix routers are summarized.In addition,current limitations and challenges of routers are studied,including routing algorithms,arbitration strategies,power consumption,performance and scalability,which will lay a solid foundation for the design of efficient router architectures.Based on the analysis of current research and various features of high-radix routers,a multi-stage bufferless high-radix router architecture is proposed.And then three-stage arbitration strategy in the Clos network is designed.The high-radix network composed with 136-port routers run well when testing with Booksim simulator.We propose and implement a new high-radix router by putting corresponding buffers on virtual channels of all switches based on the bufferless high-radix router and the method of multi-stage switching fabric,and then a new high-radix network is built by Flattened Butterfly topology.The results of performance analysis show that network latency decreases with the increase of the buffer depth in two different networks under uniform and random traffic patterns.And the latency in bufferless network is higher than that in buffered network on the condition of the same injection rate and buffer size.In summary,this thesis analyzed the current fabrics of high-radix routers and their characteristics,and then we design two new high-radix routers by multi-stage switching fabrics.Therefore,this thesis solves some practical problems in high-radix router fabric,which has both engineering value and theoretical significance.