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Re: [p2pi] WG Review: Application-Layer Traffic Optimization (alto)

2008-10-10 12:31:57

It was evident that the Dublin BoF went well but also evident that it ended
without consensus on the work that a ALTO WG should do/not do.

However, it looks to me that the 200 and more emails that followed the BoF,
allowed us to find some form of agreement on the direction ALTO community
should look at.

A few weeks later we had a new (revised) charter document. It has been sent
to the mailing list and slightly amended (nothing really substantial as I
recall). This also enforces the idea that we reached substantial consensus.

We may argue that consensus reached is not enough for a WG creation but
sincerely this is not my perception.

Naively, I tend to believe that a WG can be created once agreement exists on
problem statement and charter.

Once WG is created, consensus is anyway required for any standardization
process so, we'll have a lot of other opportunities for disagreement...

thanks.
s.

From: "Narayanan, Vidya" <vidyan(_at_)qualcomm(_dot_)com>
Date: Thu, 9 Oct 2008 23:07:21 -0700
To: "Dondeti, Lakshminath" <ldondeti(_at_)qualcomm(_dot_)com>, Richard Barnes
<rbarnes(_at_)bbn(_dot_)com>
Cc: "p2pi(_at_)ietf(_dot_)org" <p2pi(_at_)ietf(_dot_)org>, 
"'iesg(_at_)ietf(_dot_)org'" <iesg(_at_)ietf(_dot_)org>,
"ietf(_at_)ietf(_dot_)org" <ietf(_at_)ietf(_dot_)org>
Conversation: [p2pi] WG Review: Application-Layer Traffic Optimization (alto)
Subject: Re: [p2pi] WG Review: Application-Layer Traffic Optimization (alto)

Contrary to what some people seem to have interpreted my email to mean, I did
actually say that the work is needed.  I was noting the lack of consensus from
the last BoF and I definitely feel a second BoF is more appropriate at this
time to iron out the disagreements.  However, I am still not trying to block
the work - I am saying that there are some critical things to alter in the
charter proposal.

As Lakshminath notes, the notion of "service" vs. "server" is more than a
terminology issue.  It is important that we consider the possibility of ALTO
being provided as a distributed service, potentially in an overlay context.  I
also see the charter being restrictive in terms of assuming a subset of
information types to be provided by the ALTO server.  We need to shoot for a
much more generic and extensible mechanism.  Another important missing piece
is the ability for peers to publish information about themselves - without
that, the request/response protocol alone carries much less value.

Regards,
Vidya

-----Original Message-----
From: Lakshminath Dondeti [mailto:ldondeti(_at_)qualcomm(_dot_)com]
Sent: Thursday, October 09, 2008 10:17 PM
To: Richard Barnes
Cc: Narayanan, Vidya; p2pi(_at_)ietf(_dot_)org; 'iesg(_at_)ietf(_dot_)org'
Subject: Re: [p2pi] WG Review: Application-Layer Traffic
Optimization (alto)

On 10/9/2008 6:36 PM, Richard Barnes wrote:
On the contrary, I perceived pretty strong agreement at the
BoF that
the ALTO problem, as expressed in the documents and
presentations, as
an important one to solve.  There was some disagreement about
solutions, but there seemed to be agreement about the general idea
that it would be useful to create an ALTO service that could help
peers optimize their peer selection.

Richard,

The minutes
(http://www.ietf.org/proceedings/08jul/minutes/alto.txt) say
this:

+++++++++++++++
Many people agreed that this is important work for the IETF, also some
(less) people hummed against.  Hum was inconclusive - some of the "no"
hums were (in Jon's words) vehement.
+++++++++++++++

Given that there was no consensus, it would have been nice if
the sponsoring AD(s) or the IESG explained what's going on,
but then transparency, it appears, is not really a goal in
this case.  If the idea was to just go forward anyway, we
really wasted 3, may be 6 months.
  The half measures are a waste of everyone's time.


The question of "service" versus "server" in the text is a complete
non-issue, purely a matter of wording.

No it is not; please see below.

In all of the "ALTO service"
scenarios Vidya describes, there is ultimately a single host that
provides ALTO information, which you might as well call an
"ALTO server".


A distributed service is not necessarily provided by a single host.

Since it addresses an important problem, and a problem that many
people agree is important, I support moving forward with this work.

I for one think that there needs to be much more clarity on
the goals and the terminology before just moving forward and
producing useless RFCs.

regards,
Lakshminath


--Richard



Narayanan, Vidya wrote:
I am surprised to see that ALTO is being proposed for a WG
after the
last BoF concluded with no consensus whatsoever.  I think a second
BoF is more appropriate than a WG on the topic at this time.  That
said, I do see the need for this work, although I have
some comments
on the current direction.

Overall, I think we should work with the notion of an ALTO
"service"
rather than specifically an ALTO "server".  The ALTO
service may be
provided by a server, a cluster of distributed servers or as a
service in an overlay.  Although some of the charter wording talks
about a "service" rather than a "server", there is enough
mention of
a "server" entity to imply a strict client-server protocol.

As part of that, I think there are a couple of key things
that need
to be addressed here:

- A protocol that allows peers (or ALTO clients) to publish
information about themselves as part of the ALTO service.
An example
of such information may be the uplink/downlink bandwidth
of the peer.

- The ability to register information types with IANA and extend
these.  The request/response protocol should be a generic enough
container for any information that peers can provide and look for,
plus what may be available from service providers, etc.
There may be
some guidelines on how such information types can be
registered and
we may start with default ones.

Some further comments/questions inline.

-----Original Message-----
From: ietf-announce-bounces(_at_)ietf(_dot_)org
[mailto:ietf-announce-bounces(_at_)ietf(_dot_)org] On Behalf Of IESG
Secretary
Sent: Monday, October 06, 2008 1:36 PM
To: IETF Announcement list
Cc: p2pi(_at_)ietf(_dot_)org
Subject: WG Review: Application-Layer Traffic Optimization (alto)

A new IETF working group has been proposed in the
Applications Area.
The IESG has not made any determination as yet.  The
following draft
charter was submitted, and is provided for informational purposes
only.  Please send your comments to the IESG mailing list
(iesg(_at_)ietf(_dot_)org) by Monday, October 13, 2008.

Application-Layer Traffic Optimization (alto)
=============================================
Last Modified: 2008-09-29

Current Status: Proposed Working Group

Chair(s): TBD

Applications Area Director(s):

Lisa Dusseault (lisa at osafoundation.org) Chris Newman
(Chris.Newman at sun.com)

Applications Area Advisor:

Lisa Dusseault (lisa at osafoundation.org)

Mailing List:

General Discussion: p2pi at ietf.org To Subscribe:
https://www.ietf.org/mailman/listinfo/p2pi
Archive: http://www.ietf.org/pipermail/p2pi/

Description of Working Group:

A significant part of the Internet traffic today is generated by
peer-to-peer (P2P) applications used for file sharing, real-time
communications, and live media streaming.  P2P
applications exchange
large amounts of data, often uploading as much as
downloading.  In
contrast to client/server architectures, P2P applications
often have
a selection of peers and must choose.

One of the advantages of P2P systems comes from redundancy in
resource availability.  This requires choosing among download
locations, yet applications have at best incomplete information
about the topology of the network.  Applications can
sometimes make
empirical measurements of link performance, but even when
this is an
option it takes time.
The application cannot always start out with an optimal
arrangement
of peers, thus causing at least temporary reduced performance and
excessive cross-domain traffic.  Providing more
information for use
in peer selection can improve P2P performance and lower ISP costs.

The Working Group will design and specify an Application-Layer
Traffic Optimization (ALTO) service that will provide
applications
with information to perform better-than-random initial peer
selection.
ALTO services may take different approaches at balancing factors
including maximum bandwidth, minimum cross-domain traffic, lowest
cost to the user, etc.  The WG will consider the needs of
BitTorrent, tracker-less P2P, and other applications, such as
content delivery networks (CDN) and mirror selection.


What does the above sentence mean? If we are putting such a list
together, we must also take into account needs from structured P2P
overlays such as those being specified in P2PSIP.

The WG will focus on the following items:

- A "problem statement" document providing a description of the
  problem and a common terminology.

- A requirements document.  This document will list
requirements for
the ALTO service, identifying, for example, what kind of
information
P2P applications will need for optimizing their choices.

- A request/response protocol for querying the ALTO service to
obtain information useful for peer selection, and a format for
requests and
responses.   The WG does not require intermediaries
between the ALTO
server and the peer querying it.  If the requirements analysis
identifies the need to allow clients to delegate third-parties to
query the ALTO service on their behalf, the WG will
ensure that the
protocol provides a mechanism to assert the consent of the
delegating client.


Is this meant to allow for entities such as proxies to be
in the path?

- A document defining core request and response formats and
semantics to communicate network preferences to applications.
 Since ALTO services may be run by entities with
different level of
knowledge about the underlying network, such preferences may have
different representations. Initially the WG will
consider: IP ranges
to prefer and to avoid, ranked lists of the peers
requested by the
client, information about topological proximity and approximate
geographic locations.
Other usages will be considered as extensions to the charter once
the work for the initial services has been completed.


Earlier, it is mentioned that the requirements document will
determine the types of information that are useful for P2P
applications.  Given that, it seems premature to conclude
that the WG
should consider the above mentioned parameters.  Also, as
I mentioned
earlier, I think it is essential to keep the protocol and message
formats extensible and allow for exchange of any
registered information type.

Another question I have is about the assumptions around
expected peer
addressing models.  Some of the above seems to hint at IP
addresses -
is this an assumption already?

- In order to query the ALTO server, clients must first
know one or
more ALTO servers that might provide useful information.  The WG
will look at service discovery mechanisms that are in use, or
defined elsewhere (e.g.
based on DNS SRV records or DHCP options).  If such discovery
mechanisms can be reused, the WG will produce a document
to specify
how they may be adopted for locating such servers.
However, a new, general-purpose service discovery
mechanism is not
in scope.


Alternately, the clients may look for ALTO services within an
overlay.  This can be modeled as service discovery within
the overlay
- I'm, however, not suggesting that we take on solutions for that.

When the WG considers standardizing information that the
ALTO server
could provide, the following criteria are important to
ensure real
feasibility.

- Can the ALTO service technically provide that information?
- Is the ALTO service willing to obtain and divulge that
information?
- Is it information that a client will find useful?

I'm not sure how useful it is for us to answer this question.  The
protocol we develop simply needs to be a container for any
information that has a registered type and fits a certain format.

- Can a client get that information without excessive
privacy concerns
  (e.g. by sending large lists of peers)?
- Is it information that a client cannot find easily some
other way?

After these criteria are met, the generality of the data will be
considered for prioritizing standardization work, for example the
number of operators and clients that are likely to be able to
provide or use that particular data.

If we can build an extensible protocol, we don't need to
define all
possible kinds of information that get carried in it.

In any
case, this WG will not propose standards on how congestion is
signaled, remediated, or avoided, and will not deal with
information
representing instantaneous network state.
Such issues belong to other IETF areas and will be treated
accordingly by the specific area.

This WG will focus solely on the communication protocol between
applications and ALTO servers.  Note that ALTO services may be
useful in client-server environments as well as P2P environments,
although P2P environments are the first focus.  If, in
the future,
the IETF considers changes to other protocols for actually
implementing ALTO servers (e.g.
application-layer protocols for Internet coordinate
systems, routing
protocol extensions for ISP-based solutions), such work
will be done
in strict coordination with the appropriate WGs.


I hope we can also look at the above from a generalized service
perspective rather than just a client-server perspective.

Thanks,
Vidya

Issues related to the content exchanged in P2P systems are also
excluded from the WG's scope, as is the issue dealing
with enforcing
the legality of the content.

Goals and Milestones (very tentative dates):

Apr 2009: Working Group Last Call for problem statement Jun
2009: Submit problem statement to IESG as Informational Aug
2009: Working Group Last Call for requirements document Oct
2009: Submit requirements document to IESG as Informational Jan
2010: Working Group Last Call for request/response protocol Jan
2010: Working Group Last Call for usage document for
communicating
network preferences Mar 2010: Submit request/response protocol to
IESG as Proposed Standard Mar
2010: Submit usage document to IESG as Proposed Standard May
2010: Working Group Last Call of discovery mechanism Jul
2010: Submit discovery mechanism to IESG as Proposed Standard Aug
2010: Dissolve or re-charter

Initial Drafts for Consideration
- draft-marocco-alto-problem-statement-02 -- Application-Layer
Traffic Optimization (ALTO) Problem Statement
- draft-kiesel-alto-reqs-00 -- Application-Layer Traffic
Optimization
(ALTO) Requirements



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