Content Delivery Networks J. Seedorf Interconnection NEC Internet-Draft March 5, 2012 Intended status: Informational Expires: September 6, 2012 Infrastructure-to-application information exposure from an ALTO-CDNI Perspective draft-seedorf-i2aex-alto-cdni-perpective-00 Abstract Recently, there has been a discussion on "Infrastructure-to- Application Information Exposure" and the related communications requirements in fully controlled (e.g. data centers) or partially controlled environments (e.g. CDN). One possibility to expose infrastructure information to applications in the aforementioned environments is to use yet-to-be-defined ALTO extensions. This draft discusses requirements for such ALTO extensions for a specific use case: Request Routing in CDN Interconnection (CDNI). Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on September 6, 2012. Copyright Notice Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents Seedorf Expires September 6, 2012 [Page 1] Internet-Draft Infrastructure-to-application-ALTO-CDNI March 2012 carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Useful Extensions to ALTO to facilitate CDNI Request Routing with ALTO . . . . . . . . . . . . . . . . . . . . . . 4 3. Security Considerations . . . . . . . . . . . . . . . . . . . 6 4. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 6. Informative References . . . . . . . . . . . . . . . . . . . . 9 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 10 Seedorf Expires September 6, 2012 [Page 2] Internet-Draft Infrastructure-to-application-ALTO-CDNI March 2012 1. Introduction Recently, there has been a discussion on "Infrastructure-to- Application Information Exposure" and the related communications requirements in fully controlled (e.g. data centers) or partially controlled environments (e.g. CDNs) [I-D.marocco-alto-next]. One possibility to expose infrastructure information to applications in the aforementioned environments is to use ALTO [I-D.ietf-alto-protocol], or rather extension to ALTO which are yet to be investigated and specified [I-D.marocco-alto-next]. Network Service Providers (NSPs) are currently considering to deploy Content Delivery Networks (CDNs) within their networks. As a consequence of this development, there is a need for interconnecting these local CDNs. The necessary interfaces for inter-connecting CDNs are currently being defined in the Content Delivery Networks Interconnection (CDNI) WG [I-D.ietf-cdni-requirements] [I-D.ietf-cdni-problem-statement] [I-D.ietf-cdni-use-cases]. Among other protocols, ALTO has been suggested to facilitate downstream CDN selection in the context of CDNI request routing [refs.altocdni], i.e. ALTO is currently a candidate protocol for "Footprint and Capabilities Advertisment" within CDNI Request Routing. This document discusses what extensions to ALTO would be useful in case ALTO is used as a protocol within CDNI request routing, and in particular within the "Footprint and Capabilities Advertisment" part of the CDNI request routing interface. The discussion is based on the suggested extensions to ALTO proposed in [I-D.marocco-alto-next] and the examples of how ALTO could be used for downstream CDN selection within CDNI request routing in [refs.altocdni]. Seedorf Expires September 6, 2012 [Page 3] Internet-Draft Infrastructure-to-application-ALTO-CDNI March 2012 2. Useful Extensions to ALTO to facilitate CDNI Request Routing with ALTO In the following, we assume the following scenario of using ALTO for selecting a downstream CDN [refs.altocdni]: Each downstream CDN provider hosts an ALTO server which provides ALTO information (i.e. ALTO network maps and ALTO cost maps [I-D.ietf-alto-protocol]) to an ALTO client at the upstream CDN provider. A network map provided by each of several candidate downstream CDNs can provide information to the upstream CDN provider regarding the geopgraphical coverage, the location of "surrogates", or similar. In addition, an ALTO cost map can provide an upstream CDN provider information about the ''cost'' of delivering certain content via the downstream CDN which provided such a cost map. ''Cost'' in this context is a generic term; many types of costs are possible and can be useful in the context of CDNI request routing, e.g. average link load, expected delay, or monetary costs. As an example, an upstream CDN (uCDN) receives a request from an end user. Based on the IP-address of the end user, uCDN determines that it is possible to deliver the content from one of several candidate downstream CDNs (dCDN-a, dCDN-b, and dCDN-c). Assume that only the ALTO network maps provided by dCDN-a and dCDN-c indicate that these downstream CDNs can deliver content for the location of the end user requesting content. In this case, the ALTO costs maps provide useful information to the upstream CDN, uCDN, in order to make a selection decision regarding either dCDN-a or dCDN-c. From the perspective of the given scenario and example, the following proposed extensions to ALTO would be beneficial to facilitate CDNI request routing with ALTO: o Server-initiated Notifications and Incremental Updates: In case the footprint or the capabilities of a downstream CDN change abruptly (i.e. unexpectedly from the perspective of an upstream CDN), server initiated notifications would enable a dCDN to directly inform an upstream CDN about such changes. Consider the case where - due to failure - part of the footprint of the dCDN is not functioning, i.e. the CDN cannot serve content to such clients with reasonable QoS. Without server-initiated notifications, the uCDN might still use a very recent network and cost map from dCDN, and therefore redirect request to dCDN which it cannot serve. Similarly, the possibility for incremental updates would enable efficient conveyance of the aforementioned (or similar) status changes by the dCDN to the uCDN. o Content Availability on Hosts: A dCDN might want to express CDN capabilties in terms of certain content types (e.g. codecs/ Seedorf Expires September 6, 2012 [Page 4] Internet-Draft Infrastructure-to-application-ALTO-CDNI March 2012 formats, or content from certain content providers). A new endpoint property for ALTO that would be able to express such "content availability" would enable a dCDN to make available such information to an upstream CDN. This would enable a uCDN to determine if a given dCDN actually has the capabilities for a given request with respect to the type of content requested. o Resource Availability on Hosts or Links: The capabilities on links (e.g. maximum bandwidth) or caches (e.g. average load) might be useful information for an upstream CDN for optimized dowmstream CDN selection. For instance, if a uCDN receives a streaming request for content with a certain bitrate, it needs to know if it is likely that a dCDN can fulfill such stringent application-level requirements (i.e. can be expected to have enough consistent bandwidth) before it redirects the request. In general, if ALTO could convey such information via new endpoint properties, it would enable more sophisticated means for downstream CDN selection with ALTO. Seedorf Expires September 6, 2012 [Page 5] Internet-Draft Infrastructure-to-application-ALTO-CDNI March 2012 3. Security Considerations Security Considerations will be discussed in a future version of this document. Seedorf Expires September 6, 2012 [Page 6] Internet-Draft Infrastructure-to-application-ALTO-CDNI March 2012 4. Conclusion Recently, there has been a discussion on "Infrastructure-to- Application Information Exposure" and the related communications requirements in fully controlled (e.g. data centers) or partially controlled environments (e.g. CDN). One possibility to expose infrastructure information to applications in the aforementioned environments is to use yet-to-be-defined ALTO extensions. This draft considered requirements for such ALTO extensions for a specific use case: Request Routing in CDN Interconnection (CDNI). This document discussed useful extensions to ALTO in this context, i.e. what extensions would be beneficial from the CDNI perspective and why. Seedorf Expires September 6, 2012 [Page 7] Internet-Draft Infrastructure-to-application-ALTO-CDNI March 2012 5. Acknowledgements Jan Seedorf is partially supported by the COAST project (COntent Aware Searching, retrieval and sTreaming, http://www.coast-fp7.eu), a research project supported by the European Commission under its 7th Framework Program (contract no. 248036). The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the COAST project or the European Commission. Seedorf Expires September 6, 2012 [Page 8] Internet-Draft Infrastructure-to-application-ALTO-CDNI March 2012 6. Informative References [I-D.ietf-alto-protocol] Penno, R., Alimi, R., and Y. Yang, "ALTO Protocol", draft-ietf-alto-protocol-10 (work in progress), October 2011. [I-D.ietf-cdni-problem-statement] Niven-Jenkins, B., Faucheur, F., and N. Bitar, "Content Distribution Network Interconnection (CDNI) Problem Statement", draft-ietf-cdni-problem-statement-03 (work in progress), January 2012. [I-D.ietf-cdni-requirements] Leung, K. and Y. Lee, "Content Distribution Network Interconnection (CDNI) Requirements", draft-ietf-cdni-requirements-02 (work in progress), December 2011. [I-D.ietf-cdni-use-cases] Gilles, B., Watson, G., Ma, K., Eardley, P., Emile, S., and T. Burbridge, "Use Cases for Content Delivery Network Interconnection", draft-ietf-cdni-use-cases-03 (work in progress), January 2012. [I-D.marocco-alto-next] Marocco, E. and V. Gurbani, "Extending the Application- Layer Traffic Optimization (ALTO) Protocol", draft-marocco-alto-next-00 (work in progress), January 2012. [refs.altocdni] Seedorf, J., "ALTO for CDNi Request Routing", draft-seedorf-cdni-request-routing-alto-00 (work in progress), March 2012. Seedorf Expires September 6, 2012 [Page 9] Internet-Draft Infrastructure-to-application-ALTO-CDNI March 2012 Author's Address Jan Seedorf NEC Laboratories Europe, NEC Europe Ltd. Kurfuersten-Anlage 36 Heidelberg 69115 Germany Phone: +49 (0) 6221 4342 221 Email: jan.seedorf@neclab.eu URI: http://www.neclab.eu Seedorf Expires September 6, 2012 [Page 10]