On the Session Lifetime Distribution of Gnutella

Over the past few years, capturing the characteristics of the Gnutella overlay network has been one of the major research activities in distributed computing. While most of the works are focusing on the node degree distribution, upstream/downstream traffics and file distribution, only a few have been done on modeling the session lifetime distribution. A good model of the session lifetime distribution is basically a key to understand the formation and evolution of the topological structure of Gnutella. In this paper, the main objective is to present a measurement result we did in 2003 on the session lifetime distribution and make comparison with the results obtained by other researchers during 2001 to 2005. In accordance with our measurement, it is found that the lifetime distribution fits to a power law distribution with exponential cut-off. Specifically, for all t ≥ 15 minutes, Pl(t) ∝ (t/780) −1.12 exp(−t/780). By inspecting the slopes of the log-log curve (i.e. ∂ log Pl(t)/ ∂ log t) at 20 minutes (i.e. short lifetime) and 600 minutes (i.e. long lifetime), it is also found that the shape of our model matches to those curves obtained by other researchers based on the measurements in 2001, 2002 and 2004. Therefore it is observed that the session lifetime distribution of Gnutella might be an invariant characteristic independent of the technological advancement or protocol change during the period 2002 to 2005