From: Masaharu Kobashi (mkbsh@cs.washington.edu)
Date: Sun Nov 07 2004 - 15:26:41 PST
1. Main result of the paper
The paper examines the content-delivery activities to and from the UW
focusing on the transactions of four major content delivery systems:
HTTP web services, Akamai, Kazaa and Gnutella. Its findings include:
- P2P traffic accounts for over 3/4 of HTTP traffic.
- Objects delivered in P2P transactions are three orders of magnitude
larger than usual web objects.
- A small number of P2P users are consuming a disproportionately high
fraction of bandwidth.
- UW is a net content exporter.
2. Strengths in this paper
The paper provides the objective and well quantified data of the well
designed observation of the traffic.
Its findings are also interesting and valuable for improving the UW
network design to mitigate the congestion and better use the bandwidth
and caches.
3. Limitations and suggested improvements
It is desirable to analyze in more detail the characteristics of very
popular items downloaded through P2P systems. The following points are
missing in the study by the authors:
- What are the factors that make popular items?
For example, are they related to current popular movies or are they
constant and not affected by time?
- Duration of popularity of popular items.
- Demographic aspect of the P2P users and the correlations of their
download items with their demographic characteristics.
The information in the above respects helps better design caching and
bandwidth controlling policies. It also gives us more insight into
possible
future changes in the Internet transactions.
One of the findings that AVI (video format) files are the largest
among all the content types and that AVI and MPEG account for 79% of
the bytes in the traffic suggests that all AVI files should be stored
compressed by some loss-less compression tools such as gzip and bzip2.
AVI's short comings is it is not compressed. Even by a loss-less
compression
it can be as small as one tenth or even smaller of its original size
depending on the image contents.
4. Relevance today and future
The result of the paper makes valuable data for future redesign of
the networks of UW in order to best use its bandwidth and caches.
It also provides a great insight that Kazaa, which is supposed to be
designed for scalability, will not tolerate future growth of bandwidth
demand due to its design.
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