On the stationarity of TCP bulk data transfers

While the Internet offers a single best-effort service, we remark that (i) core backbones are in general over provisioned, (ii) end users have increasingly faster access and (iii) CDN and p2p solutions can mitigate network variations. As a consequence, the Internet is to some extent already mature enough for the deployment of multimedia applications and applications that require long and fast transfers, e.g. software or OS updates. In this paper, we devise a tool to investigate the stationarity of long TCP transfers over the Internet, based on the Kolomogorov-Smirnov goodness of fit test. We use BitTorrent to obtain a set of long bulk transfers and test our tool. Experimental results show that our tool correctly identify noticeable changes in the throughput of connections. We also focus on receiver window limited connections to try to relate the stationarity observed by our tool to typical connection behaviors.