Experimental Analysis of Caching Efficiency 
for YouTube Traffic in an ISP Network

In this paper, we report YouTube traffic measurements from 
Orange IP backbone network connecting residential customers. 
We exhibit its salient features in relation to the performance 
of caching. By examining the file popularity distribution, we 
show that video requests are highly volatile in that a huge 
number of files are viewed only a few times; these files are 
therefore not relevant for caching. Nevertheless, there is
a subset of files which are massively viewed by end users and
are worth caching. On the basis of this experimental observation,
we develop a mathematical model for estimating the efficiency of
file caching in the presence of noise traffic composed of those
files which are rarely requested and thus “pollute” the cache. We
then proceed to trace-driven simulations in order to check the
qualitative conclusions derived from the theoretical model.