A new IETF working group has been formed in the Applications Area. For additional information, please contact the Area Directors or the WG Chairs. Application-Layer Traffic Optimization (alto) ============================================= Last Modified: 2008-11-03 Current Status: Active Working Group Chair(s): Jon Peterson [jon.peterson@neustar.biz] Enrico Marocco [enrico.marocco@telecomitalia.it] Vijay K. Gurbani [vkg@alcatel-lucent.com] 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: alto@ietf.org To Subscribe: https://www.ietf.org/mailman/listinfo/alto Archive: http://www.ietf.org/pipermail/alto/ 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 must choose one or more suitable candidates from a selection of peers offering the same resource or service. One of the advantages of P2P systems comes from redundancy in resource availability. This requires choosing among a list of peers, yet applications have at best incomplete information to help the selection, e.g., topology of the network. Applications can sometimes obtain network information dynamically or measure link performance with respect to particular peers, but even when this is an option it takes time. The application cannot always start out with an optimal arrangement of peers, thus risking at least temporary poor 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 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, types of information P2P applications may 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 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. Other usages will be considered as charter additions once the work for the initial services has been completed. - 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. - Can the ALTO service realistically discover that information? - Is the distribution of that information allowed by the operators of that service? - 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 importance 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. 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 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 _______________________________________________ IETF-Announce@ietf.org https://www.ietf.org/mailman/listinfo/ietf-announce
