Over the past decade, there has been great interest in the study of buffer management policies in the context of packet transmission for network switches. In a typical model, a switch receives packets on one or more input ports, with each packet having a designated output port through which it should be transmitted. An online policy must consider bandwidth limits on the rate of transmission, memory constraints impacting the buffering of packets within a switch, and variations in packet properties used to differentiate quality of service. With so many constraints, a switch may not be able to deliver all packets, in which case some will be dropped.
In the online algorithms community, researchers have used competitive analysis to evaluate the quality of an online policy in maximizing the value of those packets it is able to transmit. In this article, we provide a detailed survey of the field, describing various models of the problem that have been studied, and summarizing the known results.