Buffer sizing in internet routers

直到最近，人们还普遍认为互联网路由器需要大缓冲区。今天的商用路由器具有巨大的数据包缓冲区，通常存储数百万个数据包，假设大的缓冲区会导致良好的统计多路复用，从而有效地利用昂贵的长途链路。最近，我们（在斯坦福大学的时候）展示了一个可以用更小的缓冲区构建网络——在每个路由器上只有几十个数据包缓冲区，代价是100%的链路利用率。如果这是正确的，将会产生有趣的实际结果。它可以消除构建光分组交换路由器的一个主要障碍。最近的技术进步（UCSB）也使光学FCFS数据包缓冲区成为可能，它可以在集成光电芯片中容纳几十个数据包；更大的全光缓冲器仍然不可行。

Until recently, Internet routers were widely believed to need large buffers. Commercial routers today have huge packet buffers, often storing millions of packets, under the assumption that large buffers lead to good statistical multiplexing and hence efficient use of expensive long-haul links. Recently, we (while at Stanford) showed that one can build a network with much smaller buffers still---with only a few dozen packet buffers in each router, at the expense of 100% link utilization. There are interesting practical consequences if this is correct. It could remove one major roadblock to building optical packet-switched routers. Recent advances in technology (at UCSB) also make possible optical FCFS packet buffers that can hold a few dozen packets in an integrated opto-electronic chip; larger all-optical buffers remain infeasible.