Re: [p2pi] Refining the ALTO problem statement

On 2008-6-27, at 0:21, ext Stanislav Shalunov wrote:
> 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.

It will surprise nobody that I fully agree with Stas.

Lars

>
>
> -- 
> 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/
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>
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