Evaluation of Priority Scheduling and Flow Starvation for Thin Streams with FQ-CoDel

Bufferbloat is the result of oversized buffers and induced high end- to-end latency experienced by applications across the Internet. This additional delay can adversely impact thin streams, that frequently exchange small amounts of data, but have stringent latency requirements. Active Queue Management (AQM) techniques, such as Controlled Delay (CoDel), can control the queuing delay in a network device to ensure low latency by dropping packets to indicate incipient congestion. FlowQueue-CoDel (FQ-CoDel) is a scheduling scheme that creates one sub-queue per flow and apply CoDel on each of them. FQ-CoDel features: (1) priority scheduling for low-rate traffic; (2) flow isolation; (3) queue management with CoDel. First, this paper fills a gap in the understanding of FQ- CoDel by analyzing what features are of interests for providing low latency for thin streams applications. Second, this paper provides the first analysis of the limits of the flow starvation mechanisms and show that FQ-CoDel is vulnerable to Denial of Service (DoS) attacks.