Periodic early detection for improved TCP performance and energy efficiency

Reducing the size of packet buffers in network equipment is a straightforward method for improving the network performance experienced by user applications and also the energy efficiency of system designs. Smaller buffers imply lower queueing delays, with faster delivery of data to receivers and shorter round-trip times for better controlling the size of TCP congestion windows. If small enough, downsized buffers can even fit in the same chips where packets are processed and scheduled, avoiding the energy cost of external memory chips and of the interfaces that drive them. On-chip buffer memories also abate packet access latencies, further contributing to system scalability and bandwidth density. Unfortunately, despite more than two decades of intense research activity on buffer management, current-day system designs still rely on the conventional bandwidth-delay product rule to set the size of their buffers. Instead of decreasing, buffer sizes keep on growing linearly with link capacities.We draw from the limitations of the buffer management schemes that are commonly available in commercial network equipment to define Periodic Early Detection (PED), a new active queue management scheme that achieves important buffer size reductions (more than 95%) while retaining TCP throughput and fairness. We show that PED enables on-chip buffer implementations for link rates up to 100 Gbps while relieving end users from network performance disruptions of common occurrence.