Re: [p2pi] draft-livingood-woundy-p4p-experiences-02 posted

That's a good question, and Richard and I spoke about this yesterday. I'll be looking into the data to see what the cause is. 

- Laird Popkin, CTO, Pando Networks 
mobile: 646/465-0570 

----- Original Message ----- 
From: "Robb Topolski" <robb@funchords.com> 
To: "Richard Woundy" <Richard_Woundy@cable.comcast.com> 
Cc: "Jason Livingood" <Jason_Livingood@cable.comcast.com>, p2pi@ietf.org 
Sent: Wednesday, November 5, 2008 5:42:51 PM (GMT-0500) America/New_York 
Subject: Re: [p2pi] draft-livingood-woundy-p4p-experiences-02 posted 

I don't get the part where access network download consumption increased as a result of using P4P (section 4.2). Can someone explain how that could happen? 

Robb 

On Wed, Nov 5, 2008 at 2:29 PM, Woundy, Richard < Richard_Woundy@cable.comcast.com > wrote: 

Reinaldo, 

I can answer the easy questions. We will need some assistance from Pando 
(and Yale) for some of the other ones. 

>What was the file size in those experiments? 

21 megabytes. From section 2: "Pando distributed a special 21 MB 
licensed video file as in order to measure the effectiveness of P4P 
iTrackers." 

>How long would it take to download the file in the three different 
scenarios? I know that more consumed bandwidth in access might lead one 
to conclude that file was downloaded faster... 

To clarify, most of the raw data (download speed and Internet 
peering/transit traffic volumes) were collected by Pando Networks from 
their P2P clients, not collected by Comcast across its links. So my 
assumption is that the Pando client used the content size (21 MB), and 
divided by the download time to get the speed. 

>Was the file already seeded in Comcast's network? More specifically, 
how 
was file propagation done? 

Any seeding happened outside of Comcast's network, and outside of 
Comcast's control. That's really a question for Pando. 

>Was PEX, DHT and others enabled in the clients? 

Pando would know whether PEX was enabled. It would be safe to assume 
that with respect to this trial, DHT was NOT enabled, since Pando 
supplied the tracker. (The pTracker in the draft is a tracker operated 
by Pando.) 

>Was local peer discovery enabled in the clients? 

Pando would know. 

>BTW, can broadcast/multicast peer discovery work in Cable networks? 

Do you mean something like this: 
http://bittorrent.org/beps/bep_0026.html ? 

If so, peer discovery probably would not work over the typical last mile 
cable network. Maybe I'm wrong, but I see this protocol as intended for 
peer discovery within one's home network / LAN / WiFi network, not over 
a cable network. 

>So, were clients allowed to become seeders to the outside of Comcast's 
network? 

Yes, they were. 

As a related item, look closely at section 4.2. The amount of aggregate 
uploaded data from Comcast clients (per swarm) was about 140,000 MB. The 
amount of aggregate downloaded data from Comcast clients (per swarm) was 
about 60,000 MB or so. So the typical Comcast client uploaded more than 
twice the amount of data that it downloaded. 

>How much of the swarm was within Comcast and outside? 

Most of the swarm was outside of Comcast. Unfortunately I don't have 
access to the size of the global swarm, but I would guess that Comcast 
clients represented no more than 15% of the swarm, and maybe as little 
as 5%. Those guesses are based on the behavior of the random swarm, e.g. 
Comcast clients uploaded to non-Comcast clients 94% of the time in the 
random swarm. 

-- Rich 

-----Original Message----- 
From: p2pi-bounces@ietf.org [mailto: p2pi-bounces@ietf.org ] On Behalf Of 

Reinaldo Penno 
Sent: Wednesday, November 05, 2008 11:23 AM 
To: Livingood, Jason; p2pi@ietf.org 
Subject: Re: [p2pi] draft-livingood-woundy-p4p-experiences-02 posted 

Hello Jason/Rich, 

This is such an interesting draft. I'm surprised there are no questions 
about it. Maybe everybody else is part of P4P one way or another and I'm 
not 
in the 'in' crowd (;-) so I have questions. 

* What was the file size in those experiments? Some post long ago said 
the 
file size in some P4P experiments was really small, as opposed to the 
top 
100 torrents where the file size is ~1Gb. I was curious what is the 
optimization payback in terms of download time for large files as 
opposed 
small files. 

* How long would it take to download the file in the three different 
scenarios? I know that more consumed bandwidth in access might lead one 
to 
conclude that file was downloaded faster but I'm not sure this is a 
straightforward conclusion. 

* Was the file already seeded in Comcast's network? More specifically, 
how 
was file propagation done? All clients started from scratch and had to 
start 
pulling the file from some other side of the world and then exchanging 
pieces? This is mainly due to the discussion in 4.2. 

* Was PEX, DHT and others enabled in the clients? 

* Was local peer discovery enabled in the clients? BTW, can 
broadcast/multicast peer discovery work in Cable networks? 

* If more clients finish downloading faster and become seeders you would 
think that for popular content Comcast's upstream bandwidth would 
increase 
due to the number of seeder in its network. So, were clients allowed to 
become seeders to the outside of Comcast's network? How much of the 
swarm 
was within Comcast and outside? 

Thanks, 

Reinaldo 

On 11/3/08 12:49 PM, "Livingood, Jason" 
< Jason_Livingood@cable.comcast.com > 
wrote: 

> For some reason the URL was cut to two lines - trying again: 
> 
> 
http://www.ietf.org/internet-drafts/draft-livingood-woundy-p4p-experienc 
> es-02.txt 
> 
> 
> 
>> -----Original Message----- 
>> From: p2pi-bounces@ietf.org [mailto: p2pi-bounces@ietf.org ] On 
>> Behalf Of Livingood, Jason 
>> Sent: Monday, November 03, 2008 3:35 PM 
>> To: p2pi@ietf.org 
>> Subject: [p2pi] draft-livingood-woundy-p4p-experiences-02 posted 
>> 
>> A draft at 
>> http://www.ietf.org/internet-drafts/draft-livingood-woundy-p4p 
>> -experienc 
>> es-02.txt may be of interest to folks that have been 
>> interested in P2Pi and ALTO. We have requested time on the 
>> ALTO agenda at IETF 73 to present this. 
>> 
>> Regards 
>> Jason 
>> _______________________________________________ 
>> p2pi mailing list 
>> p2pi@ietf.org 
>> https://www.ietf.org/mailman/listinfo/p2pi 
>> 
> _______________________________________________ 
> p2pi mailing list 
> p2pi@ietf.org 
> https://www.ietf.org/mailman/listinfo/p2pi 

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-- 
Robb Topolski ( robb@funchords.com ) 
Hillsboro, Oregon USA 
http://www.funchords.com/ 

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