Rate and queue controlled random drop (RQRD): a buffer management scheme for Internet routers

A buffer management scheme destined to be deployed in Internet routers should provide an adequate handling of all traffic types, including UDP and TCP traffic as well as fairness among competing flows. In core routers, keeping per-flow state and taking per-flow actions is strongly discouraged, because of the scalability issues that ensue. Consequently, core-stateless fair queuing (CSFQ) adopts a distributed architecture, and uses rate information to provide fairness in core routers. However, we show that CSFQ is sensitive to the setting of its parameters and often leads to a reduction in aggregate throughput. We present rate and queue controlled random drop (RQRD), a buffer management scheme which is based on CSFQ's distributed architecture, but adds queue size information, as in RED, and provides two drop precedences to achieve all the objectives above. We show that RQRD provides an adequate service in the context of both the present and the future Internet.