On the nature of unused TCP connections in web traffic

The popularity of the web and the requirements introduced by current web content have pushed for the development of new techniques that meet these challenges and improve the experience of the users. In particular, during the last years, web browsers have taken aggressive measures in order to reduce webpage download times. These measures have had a noteworthy effect on the profile of web traffic. One of the most striking consequences is that nowadays, more than 20% of the TCP connections opened by a browser are left unused. In this paper we describe these connections, explain why they happen and use them as a simple way of identifying the traffic of different web browsers.