Recyclable Counter With Confinement for Real-Time Per-Flow Measurement

With the amount of Internet traffic increasing substantially, measuring per-flow traffic accurately is an important task. Because of the nature of high-speed routers, a measurement algorithm should be fast enough to process every packet going through them, and should be executable with only a limited amount of memory, as well. In this paper, we use two techniques to solve memory/speed constraints: (1) recycling a memory block by resetting it (for memory constraint), and (2) confinement of virtual vectors to one word (for speed constraint). These techniques allow our measurement algorithm, called a recyclable counter with confinement (RCC), to accurately measure all individual flow sizes with a small amount of memory. In terms of encoding speed, it uses about one memory access and one hash computation. Unlike other previously proposed schemes, RCC decodes very quickly, demanding about three memory accesses and two hash calculations. This fast decoding enables real-time detection of a high uploader/downloader. Finally, RCC's data structure includes flow labels for large flows, so it is possible to quickly retrieve a list of large-flow names and sizes.