Roy Xiaorong Lai

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1. Introduction Packets are the fundamental unit of communication that move data on the Internet. A flow is a sequence of packets that share the same source and destination IP addresses, source and destination port numbers, and IP protocol. While flows vary in volume and type, a rather small number of flows consume the majority of the network bandwidth. These flows are elephant flows (elephants), and they typically last for a long time and consist of many packets and bytes.