FFTh study refutes some previous notions of network utilization and symmetry

[David Farber <dave () farber net>]

Begin forwarded message:

From: Dewayne Hendricks <dewayne () dandin com>
Date: February 20, 2006 9:58:29 AM EST
To: Dewayne-Net Technology List <dewayne-net () warpspeed com>
Subject: [Dewayne-Net] FFTh study refutes some previous notions of  
network utilization and symmetry
Reply-To: dewayne () warpspeed com

[Note:  I'm cross posting this from Bill St. Arnaud's excellent CAnet  
list.  As it turns out, I was going to post a pointer to this study  
today, which had been presented at a recent NANOG meeting <http:// 
www.nanog.org/>.  Then this item from Bill's list showed up and I  
thought that I'd use it instead.  For us purveyors of wireless  
networks, these findings on symmetry come as no surprise.  Its just  
sad that its taken the wireheads so long to catch up to our view of  
the networking world.  <g>  DLH]

> From: "Bill St.Arnaud" <bill.st.arnaud () canarie ca>
> Date: February 20, 2006 6:18:30 AM PST
> To: <news () canarie ca>
> Subject: [CAnet - news] FFTh study refutes some previous notions of  
> network utilization and symmetry
>
> For more information on this item please visit the CANARIE CA*net 4  
> Optical
> Internet program web site at http://www.canarie.ca/canet4/library/ 
> list.html
> -------------------------------------------
>
> [Interesting study of actual users on FTTh networks. Note- in Japan I
> believe that many VDSL connections are considered FTTh.  The number  
> of true
> FTTh connections is a lot smaller. Thanks to Dirk van der Woude,  
> Jaap van
> Till and Andrew Odlyzko for this pointer -- BSA]
>
>
> <http://www.iijlab.net/~kjc/tmp/rbb-20060211.pdf>
>
>
> In Japan now some 4.5 to 5 million FttH connections
> are in place, so research into the resulting traffic
> patterns is quite interesting for (yet) fiber challenged
> countries. The attached report to my knowledge is
> the first in which the effects of wide spread FttH (i.e.
> super high symmetric broadband) is measured.
>
> Classic thought says that a small group of very heavy
> users is responsible for the over large majority of traffic.
> Hence the arguments of owners of copper and coax
> networks:
> "Fiber is not necessary, the over large majority of users
> does not need it" and
> "nobody asks for symmetric bandwidth".
>
> The attached research clearly seems to point in another
> direction: users that do not have high symmetric bandwidth
> will not or less use bandwidth hungry applications.
>
> The moment these network constraints are solved they
> will at times become heavy users. Those 'heavy-hitters'
> are (at least in Japan) not a small and clear defined
> group - but anybody with access to symmetric super
> high bandwidth.
>
> So, quoting my Alderman Mark van der Horst who believes
> in short statements, "one does not buy a Ferrari in a country
> where roads are sandy paths".
>
> greetings,
> Dirk
>
>
> ===============
>
> Our per-customer measurements reveal the behavior
> of residential traffic in depth. At first, we noticed a
> large skew in traffic usage: the top 4% of heavy-hitters
> account for 75% and 60% of inbound and outbound traffic,
> respectively. Fiber traffic accounts for 86% and 75%
> of inbound and outbound traffic, respectively. We tend
> to attribute the skews to the divide between a handful
> of heavy-hitters and the rest of the users. Our in-depth
> analysis, however, shows the existence of diverse and
> widespread heavy-hitters who appear to be casual users
> rather than more dedicated users. In addition, the total
> traffic behavior seems to reflect the balance of the
> diversity.
> For example, the large skew in per-customer traffic
> seems to be caused by a small number of heavy-hitters
> but, in fact, the distribution of per-customer traffic follows
> a power law and it is difficult to draw a line between
> heavy-hitters and the rest of the users. The large skew
> in traffic volume between fiber and DSL is not caused
> by qualitative differences in the behaviors of fiber and
> DSL customers but simply by the larger percentage of
> heavy-hitters among fiber users. The large skew of userto-
> user traffic in residential traffic seemingly points to
> peer-to-peer file-sharing but it is apparently a mixture
> of file-sharing and content-downloading. All the results
> indicate that the perceived divides are actually caused
> by diversity. At the same time, the entire behavior reflects
> the balance of this diversity, but it is sometimes
> dictated by the most influential group.
> We can no longer view heavy-hitters as exceptional
> extremes since there are too many of them, and they
> are statistically distributed over a wide range. It is more
> natural to think they are casual users who start playing
> with new applications such as video-downloading
> and peer-to-peer file-sharing, become heavy-hitters, and
> eventually shift from DSL to fiber. Or, sometimes users
> subscribe to fiber first, and then, look for applications to
> use the abundant bandwidth. The implication is that, if
> a new attractive application emerges, a drastic change
> could occur in traffic usage. For example, current peerto-
> peer applications do not take locality into consideration,
> but future applications could as suggested in [13].
> As for the generality of our measurements, several aspects
> are specific to Japanese traffic. One is the high
> penetration of fiber access. It seems to take some time
> for other countries to deploy fiber access; even Korea
> that has the highest broadband penetration ratio does
> not have widespread fiber access [16]. Japan is a model
> of widespread symmetric residential broadband access.
> Another is fairly closed domestic traffic. The current
> situation is partly due to language and cultural barriers
> and partly due to rich connectivity within the
> country. The former could be common to other non-
> English speaking countries to some extent, and the latter
> can be seen simply as the geographic concentration
> of bandwidth-rich users.
>
> 7 Conclusion
> The widespread deployment of residential broadband
> access has tremendous implications on our lives. Although
> its effects on the Internet infrastructure are difficult
> to predict, it is essential for researchers and industry
> to prepare to accommodate innovations brought
> by empowered end users. Extensive effort to establish
> protected data sharing mechanisms with commercial
> Japanese Internet backbone providers has allowed
> us to achieve an unprecedented empirical analysis of a
> significant segment of the Japanese residential broadband
> traffic.
> The growth of residential broadband traffic has already
> contributed to a significant increase in commercial
> backbone traffic. In our study, residential broadband
> traffic accounts for two thirds of the ISP backbone
> traffic, which will force significant reevaluation of
> the pricing and cost structures of the ISP industry.
> We have further studied residential per-customer traffic
> in one of the ISPs, and investigated differences between
> DSL and fiber users, heavy-hitters and normal
> users, and in geographic traffic matrices. We found that
> a small segment of users dictates the overall behavior;
> 4% of heavy-hitters account for 75% of the inbound volume.
> The fiber users account for 86% of the inbound
> volume. About 62% of the residential traffic volume is
> user-to-user traffic that exhibits impressively diverse behaviors.
> The distribution of heavy-hitters follows power
> law without a clear boundary between heavy-hitters and
> normal users.
> For future work, we will continue collecting aggregated
> traffic logs from participating ISPs. We are also
> planning to do per-customer traffic analysis from other
> ISPs, and hope to compare our results with measurements
> from non-Japanese ISPs.

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