Deconstructing Datacenter Packet Transport

We present, pFabric, a minimalistic datacenter fabric design that provides near-optimal performance in terms of completion time for high-priority flows and overall network utilization. pFabrics design eliminates nearly all buffering on switches (switches have only similar to 20KB of buffering per port), requires almost no congestion con- trol and uses only simple mechanisms at each switch. Specifically, switches are only required to locally and greedily decide what packets to schedule and drop ac- cording to priorities in the packet header and do not maintain any flow state or rate estimates. Rate-control is almost unnecessary, all flows start at line-rate and only slow down in the extreme case of congestion col- lapse. We show via simulations using realistic workloads and topologies that this simple design achieves near op- timal flow completion times and network utilization.