Subject: [alto] I-D Action: draft-ietf-alto-reqs-11.txt

From: [email-masked]
Date: Mon, 11 Jul 2011 13:00:55 -0700

A New Internet-Draft is available from the on-line Internet-Drafts directories. This draft is a work item of the Application-Layer Traffic Optimization Working Group of the IETF.

	Title           : Application-Layer Traffic Optimization (ALTO) Requirements
	Author(s)       : Sebastian Kiesel
                          Stefano Previdi
                          Martin Stiemerling
                          Richard Woundy
                          Yang Richard Yang
	Filename        : draft-ietf-alto-reqs-11.txt
	Pages           : 22
	Date            : 2011-07-11

   Many Internet applications are used to access resources, such as
   pieces of information or server processes, which are available in
   several equivalent replicas on different hosts.  This includes, but
   is not limited to, peer-to-peer file sharing applications.  The goal
   of Application-Layer Traffic Optimization (ALTO) is to provide
   guidance to applications, which have to select one or several hosts
   from a set of candidates, that are able to provide a desired
   resource.  This guidance shall be based on parameters that affect
   performance and efficiency of the data transmission between the
   hosts, e.g., the topological distance.  The ultimate goal is to
   improve performance (or Quality of Experience) in the application
   while reducing resource consumption in the underlying network
   infrastructure.

   This document enumerates requirements for specifying, assessing, or
   comparing protocols and implementations.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-alto-reqs-11.txt

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

This Internet-Draft can be retrieved at:
ftp://ftp.ietf.org/internet-drafts/draft-ietf-alto-reqs-11.txt

---

From: Reinaldo Penno <[email-masked]>
Date: Sun, 17 Jul 2011 19:17:17 -0400

I have a question on how the requirement below would be operationalized.

" For example, an
      ALTO client could be integrated into the tracker of a tracker-
      based P2P application, in order to request ALTO guidance on behalf
      of the peers contacting the tracker.
"

I'm assuming the flow of information is the following: A P2P client contacts
a Tracker. The Tracker (as an ALTO Client) turns around and contacts an ALTO
Server in order to get guidance.

Later in the section is says

"   REQ.  ARv11-20: An ALTO client protocol MUST support the mode of
   operation in which the ALTO client is embedded in a third party,
   which performs queries on behalf of resource consumers."

It is not clear to me that the ALTO Client is performing the query 'on
behalf' of the P2P client.  If the requirement is written as intended, the
P2P Client needs to pass information to the tracker that needs to be
converted into parameters by the ALTO Client when issuing a query: bandwidth
caps, encryption preference, queue limit, ISP Policies, wireline vs.
wireless preference, etc.

Otherwise the third party ALTO Client can at most perform a 'plain' query
and return a cost and network map. See http://tools.ietf.org/html/rfc5632
where tracker protocol remains the same and all intelligence lives in the
'ALTO Server' or iTracker.

Therefore , is it assumed that Tracker protocols will be enhanced to pass
this information? Or the requirement wording should change a bit?

Thanks,

Reinaldo

On 7/11/11 1:00 PM, "[email-masked]" <[email-masked]>
wrote:

> A New Internet-Draft is available from the on-line Internet-Drafts
> directories. This draft is a work item of the Application-Layer Traffic
> Optimization Working Group of the IETF.
> 
> _______________________________________________
> alto mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/alto

---

From: Sebastian Kiesel <[email-masked]>
Date: Mon, 18 Jul 2011 12:31:39 +0200

Reinaldo,

> Server in order to get guidance.

... and then returns a peer list to the requesting P2P client, which
is ALTO-biased (e.g., sorted) 

See page 5 of
http://www.ietf.org/proceedings/80/slides/alto-5.pdf
for that message flow.

> behalf' of the P2P client.  

The text says that a third party (i.e., the tracker) performs an ALTO
query on behalf of the resource consumer (i.e., the peer). 
And for doing so, it needs an ALTO client.

> If the requirement is written as intended, the

One option ...

> 'ALTO Server' or iTracker.

... the other option. The intelligence could also be in the P2P tracker
doing peer pre-selection based on ALTO and other information sources.

> this information? 

I see reasonable use cases both with and without modifying the
peer-tracker protocol. But the peer-tracker protocol is out of the scope
of this document, and I think this question has no impact on the ALTO
client protocol.

The most important implication of this requirement is IMO that there
must be a field "resource consumer address" in the ALTO protocol (or
maybe in an underlying layer but not the IP source address).

> Or the requirement wording should change a bit?
How?

Thanks,
Sebastian

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From: Reinaldo Penno <[email-masked]>
Date: Mon, 18 Jul 2011 10:20:38 -0400

Thanks, I agree.