A very strong reason universities should require students use P2P protocols.

[David Farber <dave () farber net>]

________________________________________
From: Bob Frankston [bob37-2 () bobf frankston com]
Sent: Monday, July 14, 2008 10:15 AM
To: David Farber; 'ip'
Cc: 'Dan Lynch'; ': Dr. Lawrence Roberts'; 'Lauren Weinstein'
Subject: A very strong reason universities should require students use P2P protocols.

If this is really P2P then with 20,000 students over the course of a semester it is highly likely that 99% of the 
content will be available locally at full local network speed. A video stream for viewing at a few Mbps is a minor 
local load for local traffic on a network with 1Gbps managed switches in every closet.

So this is a very strong case for P2P protocols to the point that universities should require them both for external 
content and community content shared among students within and among universities and other communities.

DRM strategies that frustrate caching are problematic because they can require each viewer have a real time stream 
direct from an approved source to an approved screen with “cable” being a particular wasteful and costly example. Given 
that the constriction model of network management creates huge artificial costs other business models would make sense 
but that’s a separate topic – for this discussion it’s useful to observe that DRM approaches create costs and 
annoyances that can easily outweigh the benefits of using them.

A 1Gbps is a very small connection for a very big university. At very least the university must have direct peering 
with all the local paths so students can participate in classes and other activities even if not living on campus.

Thanks for making a strong case for P2P.




-----Original Message-----
From: David Farber [mailto:dave () farber net]
Sent: Monday, July 14, 2008 07:00
To: ip
Subject: [IP] Marketplace story on FCC and Comcast





________________________________________

From: Dr. Lawrence Roberts [lroberts () anagran com]

Sent: Sunday, July 13, 2008 9:53 PM

To: Dan Lynch; David Farber; lroberts () anagran com

Subject: Re: [IP] Marketplace story on FCC and Comcast



Dan,

For those who want to watch a movie per day, downloading a 3 GB movie at 500 Kbps takes 13 hrs, about all you want to 
spend on it. However you also must in return send out 3 GB of your stored movies each day for the system to work. If 5% 
of a University student body does this, a 20,000 student University would require 500 Mbps each way during the 13 peak 
hours. So you see, it is easy to consume 1/2 Mbps per person. Is there a limit? Yes I would think so. 2-3 movies per 
day seem like the most one could consume. But some of these students use 5 Mbps continuously. So when I say unlimited 
appetite, I mean within the context of current average people usage which is much lower.



An Example:

If a University has 5000 students and 180 of them use 1/2 Mbps for the peak period then the average data rate over a 
100 Mbps Internet access will be 20 Kbps and each P2P user is using 25 flows. There will be another 500 average users 
trying to operate one flow at any moment and they also will get 20 Kbps. 90% of the capacity is going to P2P.

Larry





At 03:56 PM 7/13/2008, Dan Lynch wrote:

Larry, I don't doubt your measurements, but gee, are you saying that P2P has

an "unlimited" appetite?  As if there are an unlimited number of files to be

shared and the queue stretches to infinity?  Where is that demand coming

from?  I am imagining hordes of files out there that people are adding to

their Torrent lists as the pipes come slightly unclogged. Is that your model

of demand?



Dan



PS.  Too bad storage got so cheap! Else someone could be making more money

out of that!





On 7/13/08 2:28 PM, "David Farber" <dave () farber net> wrote:



>

> ________________________________________

> From: Dr. Lawrence Roberts [lroberts () anagran com]

> Sent: Sunday, July 13, 2008 3:08 PM

> To: David Farber; Dr. Lawrence Roberts

> Subject: RE: Marketplace story on FCC and Comcast

>

> Dave,

> Sure! I want people to start understanding the dynamics of the problem.

> Please add me also if that,s ok so I can see comments.

> Larry

>

>

> At 02:44 AM 7/13/2008, David Farber wrote:

> Can I repost to my IP list?

>

> ________________________________________

> From: Dr. Lawrence Roberts [lroberts () anagran com]

> Sent: Saturday, July 12, 2008 11:43 PM

> Subject: RE: Marketplace story on FCC and Comcast

>

> Jeff,

> Like George, I agree the DSL and FTTX ISP's will not shift, but there is

> another reason. The DSL companies have just as big or larger problem with P2P

> since P2P expands to fill any capacity. In fact, as I have been testing and

> modeling P2P I find it taking up even higher fractions of the capacity as the

> total capacity expands. This is because each P2P app. can get more capacity

> and it is designed to take all it can. In the Univerisities we have measured,

> the P2P grows to between 95-98% of their Internet usage. It does this by

> reducing the rate per flow lower and lower, which by virtue of the current

> network design where all flows get equal capacity, drives the average rate per

> flow for average users down to their rate. They then win by virtue of having

> more flows, up to 1000 per user. I suspect they do not do this on cable since

> the upstream capacity is only 10 Mbps and when it saturates, they must stop at

> about 80%. But raise the capacity per user and the capacity of the upstream

> choke point and watch out! P2P can consume virtually any capacity.

> Larry

>

>

>

>

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