Re: [p2pi] Refining the ALTO problem statement

Knowledge about congestion is a transport topic.  Improvements in  
transport are possible, and, I would argue, necessary.  Congestion  
information is useful on entirely different timescales and is a very  
different problem.  An uncongested path may well be congested seconds  
later.  An inexpensive path is likely to remain such tomorrow and even  
a week later.

Congestion pricing and variations of ECN to achieve it is a very  
interesting topic, but not an ALTO topic.

-- 
Stanislav Shalunov
http://shlang.com

On Jun 26, 2008, at 10:54 AM, Laird Popkin wrote:

> I agree with Stanislav's main point (ALTO should focus on providing  
> new information). We've had extensive email chains listing such  
> opportunities, so no need to repeat them here.
>
> That being said, there's some value in knowing about congestion more  
> precisely than we do now. In particular, it would be good to know  
> when:
>
> 1) The user's internet connection is saturated (and in which  
> direction) so that the application as a whole can reduce bandwidth  
> to de-saturate the link. Many p2p apps do this now, but the  
> techniques for attempting to indirectly detect 'edge' link  
> saturation are inconsistent in their effectiveness. If the edge  
> router could tell app's the precise situation, that would help app's  
> avoid saturating links while maximizing performance.
>
> 2) A specific TCP stream to a specific peer is saturated, in which  
> case we should slow down that stream and pull more data from  
> elsewhere. Re-ECN looks like it'll address the latter scenario.  
> What's the relationship (if any) between Re-ECN and ALTO?
>
> - Laird Popkin, CTO, Pando Networks
>  mobile: 646/465-0570
>
> ----- Original Message -----
> From: "Stanislav Shalunov" <shalunov@shlang.com>
> To: "John Leslie" <john@jlc.net>
> Cc: p2pi@ietf.org
> Sent: Monday, June 23, 2008 7:58:39 PM (GMT-0500) America/New_York
> Subject: Re: [p2pi] Refining the ALTO problem statement
>
> On Mon, Jun 23, 2008 at 9:45 AM, John Leslie <john@jlc.net> wrote:
>>  P2P applications have good reason to want to know (instantaneous)
>> congestion, and what the likelihood is that the congestion will get
>> better or worse soon.
>
> This is the function of transport.  P2P apps, by doing e2e
> measurements, already have pretty decent information about state of
> congestion, and use it just the way you'd expect.
>
> What P2P apps don't have, and what ALTO should provide, is new
> information -- not whether a path is congested, but whether a path is
> preferred by the ISP.  Some simple notion of cost or preferred ASes or
> IP prefixes or whatnot.
>
> This is information that the routing layer has and that the overlay
> routing in P2P has no access to.
>
> --
> Stanislav Shalunov
> http://shlang.com/
> _______________________________________________
> p2pi mailing list
> p2pi@ietf.org
> https://www.ietf.org/mailman/listinfo/p2pi

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