Improving TCP performance with bufferless token bucket policing: A TCP friendly policer

TCP's flow control mechanism reacts to drops anywhere in an end-to-end data path and tries to adjust its rate to the congested link. In this paper we discuss the performance of TCP when drops occur not due to congestion but due to policing. Policing is an essential element for enforcing Service Level Agreements (SLAs). These SLA policing related packet drops are inevitable even if these is enough capacity in the network. The widely used token-bucket policer provides a low-latency, low-cost policing solution but induces bursty packet drops. These bursty packet drops interact with TCP's congestion control mechanism resulting in throughputs lower than the policed (SLA) rate. In this paper we propose an improvement to the tokenbucket policer. Our novel scheme uses a dynamic (Virtual) bucket depth, which induces a different packet drop pattern beneficial for TCP performance. We analyze the preformance of this method for a wide variety of sencarios.