A dynamic congestion management system for InfiniBand networks

While the InfiniBand link-by-link flow control helps avoid packet loss, it unfortunately causes the effects of congestion to spread through a network. Flows whose paths do not even pass through congested ports could suffer from reduced throughput. We propose a Dynamic Congestion Management System (DCMS) to address this problem. Without per-flow information, the DCMS leverages performance counters of switch ports to detect onset of congestion, and determines whether-or-not victim flows are present. The DCMS then takes actions to cause an aggressive reduction in the sending rates of congestion-causing (contributor) flows if victim flows are present. On the other hand, in the absence of victim flows, the DCMS allows the contributor flows to maintain high sending rates and finish as quickly as possible.Our results show that dynamic congestion management can enable a network to serve both contributor flows and victim flows effectively. The DCMS solution operates within the constraints of the InfiniBand Standard.