ISP: A High Performance Crossbar Arbitrating Algorithm
Zhi Jie Sun · Chinese Journal of Computers · 2000
Switch is very important to a high performance router. Today's high performance core routers always use input queue based crossbar switches. A high performance crossbar arbitrating algorithm is very important to the router design. This paper presents a combined polling and round robin algorithm, Input Serial Polling(ISP). ISP has almost the same performance with iSLIP algorithm when the load is low, but when the load is very high, ISP can achieve higher throughput, shorter cell delay and better equity than iSLIP. ISP algorithm is simple. Sixteen port ISP arbiter can be implemented by programmable logic, with working frequency as high as 65MHz. it can complete one arbitration within 250ns, so it can be used in high performance core routers.