Revisiting web traffic from a DSL provider perspective : the case of YouTube

Video oriented social networks like YouTube have altered the characteristics of Web traffic, as video transfers are carried over the legacy http port 80 using flash technology from Adobe. In this paper, we characterize the impact of YouTube traffic on an ADSL platform of a major ISP in France, connecting about 20,000 users. YouTube is a popular application as about 30% of the users have used this service over the period of observation. We first observe that YouTube video transfers are faster and larger than other large Web transfers in general. We relate the throughput performance of YouTube Web transfers to the larger capacity of YouTube streaming servers, even though the distribution strategy of YouTube is apparently to cap the throughput of a transfer to a maximum value of approximately 1.25 Mbits/s. We further focus on the cases where the throughputs of YouTube transfers is lower than the playback rate of the video. We relate the bad performance of those transfers to the load on the ADSL platform, thus excluding other root causes like congestion between YouTube streaming servers and the ADSL platform. Secondly, we focus on YouTube users' behaviors. We have discovered that about 40% of the video transfers were aborted by the client while in 19% of the cases, the client was performing at least one jump action while viewing the video. We show that abortions are only weakly correlated with the throughput achieved during the video transfers, which suggests that the main reason behind a video viewing abortions is the lack of interest for the content, rather than low network throughputs.