Adaptive CSFQ: determining the packet dropping probability adaptively for achieving fair bandwidth allocations in SCORE networks

In stateless core (SCORE) networks, edge routers maintain per flow state while core routers do not. Core stateless fair queuing (CSFQ) has been proposed for approximating the operation of per-flow queuing techniques in SCORE networks. However, the packet dropping probability offered by CSFQ suits only UDP flows. Thus, CSFQ cannot achieve fair bandwidth allocation for TCP flows. This paper proposes adaptive CSFQ (ACSFQ). The packet dropping probability in ACSFQ is determined adaptively based on the flow arrival rate, the fair share rate, and the current queue length. It well supports TCP flows as well as UDP flows. We compare ACSFQ to CSFQ in terms of fair bandwidth allocation. This paper also proposes how to identify and penalize unresponsive flows without managing their flow state. The method is simple to realize because only the packet dropping probability is changed.