Analysis of Backward Congestion Notification (BCN) for Ethernet In Datacenter Applications

IEEE 802.1 standards committee is working on a new specification for congestion notification in Ethernet networks. The goal of this work is to enable application of Ethernet in backend datacenter applications. Such applications typically use fiber channel and infiniband due to their loss-free characteristics. A backward congestion notification (BCN) scheme is one of the candidate schemes proposed to avoid long delays and minimize loss in Ethernet networks. This paper presents an analysis of this scheme. We develop an analytical model to analyze the stability and the rate of convergence of the scheme. It is shown that BCN achieves proportional fairness and not max-min fairness under certain circumstances. Simulation results are presented that validate the analytical results.