Analysis of UDP Traffic Usage on Internet Backbone Links

It is still an accepted assumption that Internet traffic is dominated by TCP. However, the rise of new streaming applications (e.g. IPTV such as PPStream, PPLive) and new P2P protocols (e.g. uTP) trying to avoid traffic shaping techniques (such as RST packet injection) are expected to increase the usage of UDP as transport protocol. Since UDP lacks congestion-control, this could potentially raise serious concerns about fairness and stability in the Internet. The goal of this paper is to shed some lights on the assumption that TCP is the dominant transport protocol on the Internet. We evaluate the amount of UDP and TCP traffic, in terms of flows, packets and bytes, on traces collected in the period 2002-2009 on several backbone links located in the US and Sweden. According to our best available data,the use of UDP as transport protocol is gaining popularity in the recent years, especially in terms of flow numbers. A first analysis suggests that most UDP flows use random high ports and carry few packets and little data. This indicates that the recent increases in UDP traffic are a side product of the general increase of P2P traffic, using random ports in order to evade detection and utilizing UDP as signaling traffic for establishing P2P overlay networks.