Network Working Group M.O. van Deventer Internet-Draft R. van Brandenburg Intended status: Informational TNO Expires: September 29, 2011 March 28, 2011 Content Terminology in CDN Interconnection draft-deventer-cdni-content-terminology-00 Abstract This internet-draft describes how the term content might take on various meanings in different Content Delivery Network (CDN) interconnection scenarios. In order to solve this ambiguity, some additional terminology to describe content in CDNs is introduced. 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/. 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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. van Deventer & van Brandenburg Expires September 29, 2011 [Page 1] Internet-Draft Content Terminology in CDN-I March 2011 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Newspaper metaphor . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Introduction to newspaper metaphor . . . . . . . . . . . . 3 2.2. Different stages of content . . . . . . . . . . . . . . . . 4 3. Content Terminology . . . . . . . . . . . . . . . . . . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 6. Informative References . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 van Deventer & van Brandenburg Expires September 29, 2011 [Page 2] Internet-Draft Content Terminology in CDN-I March 2011 1. Introduction The goal of this document is to present some terminology to be used when talking about content in the different stages of CDN interconnection. This is done by introducing a metaphor for the electronic content delivery ecosystem to provide a better understanding of the different fases of content in this ecosystem. The metaphor of a newspaper distribution ecosystem was chosen, as that ecosystem is well understood and it has many aspects in common with content delivery. Of course, any metaphor should be used with care, as there will always be (subtle) differences. 1.1. Terminology This document uses the terminology defined in section 1.1 of [I-D.jenkins-cdni-problem-statement] and [I-D.bertrand-cdni-use-cases] 2. Newspaper metaphor Using the metaphor of the newspaper distribution ecosystem, this section will describe why the term Content might have a different meaning depending on which fase in the Content Delivery chain one is talking about. 2.1. Introduction to newspaper metaphor A Newspaper company can be compared to a Content Provider (or Content Aggregator); its business is to generate and/or collect news items and other articles, and bring those together into newspapers. The audience for the newspapers are Newspaper Readers (End Users). Just as Content Providers, different Newspaper Companies may have different business models, including subscription-based, advertising- based or other. Getting newspapers to Newspaper Readers is essential to the Newspaper Company, just as it essential for a Content Provider to bring content to an End User. Some Newspapers Companies may have their own printing press, trucks to move the printed newspapers, outlets for Readers to pick up the newspapers and personnel to get newspapers deliverd to mailboxes of Newspaper Readers. However, Newspaper Companies may also decide to outsource some or all of those newspaper-distribution activities to specialized companies. o Printing Companies have one or more printing presses to print newspapers. van Deventer & van Brandenburg Expires September 29, 2011 [Page 3] Internet-Draft Content Terminology in CDN-I March 2011 o Postal Companies have one or more trucks and personnel to move and deliver printed newspapers. o Newsstand Companies have one or more newsstands where people can pick up newspapers. These different companies in the Newspaper delivery chain can be compared to the different roles in the Content Delivery Network chain. There is a role for companies to replicate, or transcode, content. There is a role for companies to perform the large scale distribution of content and there is a role for companies to perform the actual delivery of content to End Users. Just as is common in the newspaper world, companies in the Content Delivery world may take on multiple roles. 2.2. Different stages of content While the contents of the newspaper do not change during the newspaper distribution path from Newspaper Company all the way to Newspaper Reader, the form the newspaper takes during the distribution path does change. The Newspaper Company does not directly create the final newspaper that Readers find on their doorstep. What the Newspaper Company creates and delivers to the Printing Company is a printing plate, a mastercopy, of the newspaper. The Printing Company then uses this printing plate to create a number of replicas (mastercopy replicas) to use in all of its printing facilities. Based on these replicas, the actual newspapers (the consumables) are printed. These printed newspapers are then ditributed by a network of trucks to one or more distribution centra. How the newspapers end up in the hands of to the Newspaper Reader depends on the preferences (and location) of that Reader. Some Readers might pick it up at a Newsstand Company, while others will have it delivered by a Postal Company. A path similar to the one taken by the newspaper is also taken by a piece of Content in the Content Delivery Network chain. The Content Provider does not necessarily create the final piece of content, or the form it takes, that is received by the End User. Along the way the Content might be transcoded to use a different codec, repackaged in a different video container, and delivered using different transport mechanisms and protocols. In some situations, it might be useful to be able to distinguish between the different fases and forms content goes through in the content delivery chain. For example, in the case of CDN Interconnection: When talking about how an Upstream CDN ingests content into a Downstream CDN, it is important to know what the term 'content' in this case means. Is it the content in the form as it van Deventer & van Brandenburg Expires September 29, 2011 [Page 4] Internet-Draft Content Terminology in CDN-I March 2011 was first ingested into the Upstream CDN by the Content Provider? Or is it the content in its multiple transcoded forms as stored on the Upstream CDN? The current terminology does not allow for distinguishing between these different fases and forms of content in the content delivery chain. 3. Content Terminology As shown in the previous section, the term content might take on a different meaning depending on which fase in the delivery chain one is talking about. It would therefore be useful to create some additional terminology to describe these different content phases. What follows is a first attempt at describing the different forms of content as found in a CDN. Mastercopy: The content as it is delivered by the Content Provider to the (Upstream) CDN during the Content Ingestion process. Replica: The content as it is transferred between the Upstream CDN and the Downstream CDN. Consumable: The content as it is stored on a CDN delivery node directly prior to being delivered to an End User. A Consumable might be transcoded from the origal Mastercopy or Replica in order to make it suitable for a specific type of end device. Furthermore, a Consumable might be a single file or consist of multiple files/ segments that are the result of a segmentation operation having been performed on the content (e.g. to allow for specific transport mechanisms such as HTTP Adapative Streaming (HAS) to be used). It should be noted that this terminology is purely meant for indicating the role of a particular piece of content in a particular situation; it does not mean that a Consumable and a Mastercopy cannot be bit-for-bit equivalent. 4. IANA Considerations This memo includes no request to IANA. 5. Security Considerations This memo includes no security considerations. van Deventer & van Brandenburg Expires September 29, 2011 [Page 5] Internet-Draft Content Terminology in CDN-I March 2011 6. Informative References [I-D.bertrand-cdni-use-cases] Bertrand, G., Stephan, E., Watson, G., Burbridge, T., and P. Eardley, "Use Cases for Content Distribution Network Interconnection", draft-bertrand-cdni-use-cases-01 (work in progress), January 2011. [I-D.jenkins-cdni-problem-statement] Niven-Jenkins, B., Faucheur, F., and N. Bitar, "Content Distribution Network Interconnection (CDNI) Problem Statement", draft-jenkins-cdni-problem-statement-02 (work in progress), March 2011. Authors' Addresses M. Oskar van Deventer TNO Brassersplein 2 Delft, the Netherlands Phone: +31 88 86 67078 Email: oskar.vandeventer@tno.nl Ray van Brandenburg TNO Brassersplein 2 Delft, the Netherlands Phone: +31 88 86 63609 Email: ray.vanbrandenburg@tno.nl van Deventer & van Brandenburg Expires September 29, 2011 [Page 6]