All,
We have submitted a draft explaining the overall problem of peer selection -
http://www.ietf.org/internet-drafts/draft-saumitra-alto-multi-ps-00.txt.
Below are my suggested revisions to the charter based on arguments the draft
puts forth (and based on emails exchanged over the last several days).
Thanks,
Vidya
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From: ietf-announce-bounces(_at_)ietf(_dot_)org
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Sent: Monday, October 06, 2008 1:36 PM
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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.
Add: "Peer selection is also a problem that has many different applications in
p2p systems - e.g., identifying the best peer to download content from,
identifying the best super peer to contact in a system, using the best relay
for NAT traversal, identifying the best next hop for a query based on several
criteria (e.g., quality, reputation, semantic expertise, etc.), etc."
One of the advantages of P2P systems comes from redundancy in
resource availability. This requires choosing among download
locations,
s/download locations/a list of peers
yet applications have at best incomplete
information about the topology of the network.
s/incomplete information about the topology of the network/incomplete
information to help the selection, e.g., 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
s/including/such as
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.
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.
I propose deleting "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.
I suggest replacing this with Stanislav's suggestion:
"A complete mechanism that enables clients to learn from the ALTO service
information useful for peer selection".
The WG does not require intermediaries between the ALTO
server and the peer querying it.
s/the ALTO server and the peer querying it/the communicating ALTO endpoints.
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.
- 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.
The above seems okay.
Other usages will be considered as extensions to the charter
once the work for the initial services has been completed.
I think we should delete the sentence above.
- 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.
When the WG considers standardizing information that the ALTO
server could provide, the following criteria are important to
ensure real feasibility.
In the context of standardization, I don't think we should be trying to
evaluate the importance of any information. The idea for us should be to
standardize mechanisms to exchange peer selection related information. The
value of the actual information exchanged is very contextual and not for
general evaluation.
- 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?
- 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.
The above again gets into our evaluation of what is important based on what we
know today and is limiting.
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.
s/applications and ALTO servers/ALTO endpoints
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
s/servers/services
(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.
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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