what-when-how
In Depth Tutorials and Information
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Figure6.5
Theblockvariationofthepiecepopulationinthefeistytorrent.
of them, which is a short-lived torrent, for which the results are in section “he
PlanetLab-1 Torrent.”
6.2.1.4 The PlanetLab-1 Torrent
Figure 6.6 shows the evolution of the PlanetLab-1 torrent over the period of 12
hours that we simulated it. his system is in the startup stage (as seen by the single
seed that is available) through most of the experiment, transitioning to the transient
stage after approximately 9 hours. he system then moves quickly to an end stage
not seen in the other real torrents, as no new clients join the system but many are
completing their download, and many are leaving the system.
Figure 6.7 shows three representative plots of the piece population in the
PlanetLab-1 torrent, as well as itted normal distributions. he normal distribution
does not match the first two plots at all, as most pieces suffer from a low replica-
tion rate, while peaks higher in the population show some pieces have a much
higher replication rate. his is due to the limited upload bandwidth of the original
seed, and the time it takes for a single copy of the file to be present in the network
(approximately 9 hours). However, the third population at 10 hours shows that the
torrent takes very little time to become very narrowly distributed after the first full
copy of all pieces are present in the network.
