Tracking down Skype traffic

Skype is beyond any doubt the most popular VoIP application in the current Internet application spectrum. Its amazing success drawn the attention of telecom operators and the research community, both interested in knowing Skype's internal mechanisms, characterizing, traffic and understanding users' behavior. In this paper, we dissect the following fundamental components: data traffic generated by voice and video communication, and signaling trallic generated by Skype. We use both active and passive measurement techniques to gather a deep understanding on the traffic Skype generates. From extensive testbed experiments, we devise a source model which takes into account: i) the service type, i.e., voice or video calls ii) the selected source Codec, iii) the adopted transport-layer protocol, and iv) network conditions. Furthermore, leveraging on the use of an accurate Skype classification engine that we recently proposed, we study and characterize Skype trallic based on extensive passive measurements collected from our campus LAN.