ShareStreams: a scalable architecture and hardware support for high-speed QoS packet schedulers

ShareStreams (scalable hardware architectures for stream schedulers) is a unified hardware architecture for realizing a range of wire-speed packet scheduling disciplines for output link scheduling. This paper presents opportunities to exploit parallelism, design issues, tradeoffs and evaluation of the FPGA hardware architecture for use in switch network interfaces. The architecture uses processor resources for queuing and data movement and FPGA hardware resources for accelerating decisions and priority updates. The hardware architecture stores state in register base blocks, stream service attributes are compared using single-cycle decision blocks arranged in a novel single-stage recirculating network. The architecture provides effective mechanisms to trade hardware complexity for lower execution-time in a predictable manner. The hardware realized in a Virtex-I and Virtex-II FPGA can meet the packet-time requirements of 10 Gbps links for 256 stream queues with window-constrained scheduling disciplines. The hardware can schedule 1536 stream queues with priority-class/fair-queuing scheduling disciplines using 16 service-classes to meet 10 Gbps packet-times.