一种多优先级变长调度星载IP交换机交换结构的设计

摘要

Considering the hardware resources limitation in the satellite onboard IP switch ,a high capacity shared memory switch fabric with 8 priorities ,variable-length packets scheduling mechanisms and pointer copy is presented .The specific structure , the key scheduling algorithm and the working processes of the circuits are provided .Xilinx V4sx55 FPGA are used to realize a 8 × 8 switch fabric ,the circuits occupy 164K bytes on-chip memory resources and 5982 4 input lookup tables ,which can meet the re-quirements of triple modular redundancy .When the working frequency is 100MHz ,64 bit width off-chip SRAM ,the peak throughput of the switch fabric can reach 1 .6Gbps .Using 64 bit width ,133MHz DDR off-chip memory ,the peak throughputs can reach 4 . 25Gbps .The fabric can be used in multi-stage switch fabrics which can meet the demand of throughputs over 10Gbps .%针对星载IP交换机中硬件资源使用受限的情况，设计实现了一种具有8个优先级、采用指针复制和变长分组调度机制的大容量共享存储交换结构，给出了电路的具体组成、关键调度算法和工作流程．使用Xilinx V4sx55 FPGA实现了完整的8×8交换结构，电路共占用了164K字节片上存储器资源和5982个4输入查找表，可以满足三模冗余设计要求．在系统工作主频为100MHz、片外采用SRAM、数据位宽为64的情况下，交换结构的峰值吞吐率可以达到1．6Gbps；片外采用133MHz DDR存储器、位宽为64时，交换结构的峰值吞吐率可以达到4．25Gbps；该交换单元进行多级扩展后，可以满足10Gbps以上的系统设计需求．