We investigate in this paper the time evolution and the composition in terms of applications of traffic in two different networks, namely the Renater network, dedicated to the French academic and research community, and the France Télécom backbone network supporting commercial traffic. For each network, we present the time evolution of traffic in terms of applications, the associated pie charts for global results, as well as, for each detected application, its flow size distribution, that should have an impact on the traffic nature (self-similarity or long range dependence due to the heavy tail of flow size distribution). Based on these results, this paper presents a discussion on the differences between academic and commercial traffic in terms of usage, as well as possible solutions against lrd and its associated degradation of network performance. For traffic analysis, we propose a new method of classifying traffic according to applications, which relies on applicative protocols recognition instead on the iana ports numbers.