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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group M.O. van Deventer 3 Internet-Draft R. van Brandenburg 4 Intended status: Informational TNO 5 Expires: January 2, 2012 July 1, 2011 7 Content Terminology in CDN Interconnection 8 draft-deventer-cdni-content-terminology-01 10 Abstract 12 This internet-draft describes how the term content might take on 13 various meanings in different Content Delivery Network (CDN) 14 interconnection scenarios. In order to solve this ambiguity, some 15 additional terminology to describe content in CDNs is introduced, in 16 alignment with terminology developed by the ETSI MCD CDN-I Working 17 Group. 19 Status of this Memo 21 This Internet-Draft is submitted in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF). Note that other groups may also distribute 26 working documents as Internet-Drafts. The list of current Internet- 27 Drafts is at http://datatracker.ietf.org/drafts/current/. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 This Internet-Draft will expire on January 2, 2012. 36 Copyright Notice 38 Copyright (c) 2011 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (http://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with respect 46 to this document. Code Components extracted from this document must 47 include Simplified BSD License text as described in Section 4.e of 48 the Trust Legal Provisions and are provided without warranty as 49 described in the Simplified BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 54 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 55 2. Newspaper metaphor . . . . . . . . . . . . . . . . . . . . . . 4 56 2.1. Introduction to newspaper metaphor . . . . . . . . . . . . 4 57 2.2. Different stages of content . . . . . . . . . . . . . . . . 5 58 3. Content Terminology . . . . . . . . . . . . . . . . . . . . . . 6 59 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 60 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 61 6. Informative References . . . . . . . . . . . . . . . . . . . . 8 62 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 64 1. Introduction 66 The goal of this document is to present some terminology to be used 67 when talking about content in the different stages of CDN 68 interconnection. The additional terminology is aligned with CDN 69 interconnect terminology developed by the ETSI MCD Working Group on 70 CDN Interconnection (MCD WG CDN-I). Documents developed by ETSI MCD 71 in the CDN area are publicly available from the ETSI MCD Open Area 72 http://docbox.etsi.org/MCD/Open/. 74 This document introduces a metaphor for the electronic content 75 delivery ecosystem to provide a better understanding of the different 76 phases of content in this ecosystem. The metaphor of a newspaper 77 distribution ecosystem was chosen, as that ecosystem is well 78 understood and it has many aspects in common with content delivery. 79 Of course, any metaphor should be used with care, as there will 80 always be (subtle) differences. 82 1.1. Terminology 84 This document uses the terminology defined in section 1.1 of [I- 85 D.jenkins-cdni-problem-statement] and [I-D.bertrand-cdni-use-cases] 86 and terminology used in [ETSI TS 102 990 v0.0.7]. 88 2. Newspaper metaphor 90 Using the metaphor of the newspaper distribution ecosystem, this 91 section will describe why the term Content might have a different 92 meaning depending on which phase in the Content Delivery chain one is 93 talking about. 95 2.1. Introduction to newspaper metaphor 97 A Newspaper company can be compared to a Content Provider (or Content 98 Aggregator); its business is to generate and/or collect news items 99 and other articles, and bring those together into newspapers. The 100 audience for the newspapers are Newspaper Readers (End Users). Just 101 as Content Providers, different Newspaper Companies may have 102 different business models, including subscription-based, advertising- 103 based or other. 105 Getting newspapers to Newspaper Readers is essential to the Newspaper 106 Company, just as it essential for a Content Provider to bring content 107 to an End User. Some Newspapers Companies may have their own printing 108 press, trucks to move the printed newspapers, outlets for Readers to 109 pick up the newspapers and personnel to get newspapers delivered to 110 mailboxes of Newspaper Readers. However, Newspaper Companies may also 111 decide to outsource some or all of those newspaper-distribution 112 activities to specialized companies. 114 o Printing Companies have one or more printing presses to print 115 newspapers. 117 o Postal Companies have one or more trucks and personnel to move and 118 deliver printed newspapers. 120 o Newsstand Companies have one or more newsstands where people can 121 pick up newspapers. 123 These different companies in the Newspaper delivery chain can be 124 compared to the different roles in the Content Delivery Network 125 chain. There is a role for companies to replicate, or transcode, 126 content. There is a role for companies to perform the large scale 127 distribution of content and there is a role for companies to perform 128 the actual delivery of content to End Users. Just as is common in the 129 newspaper world, companies in the Content Delivery world may take on 130 multiple roles. 132 2.2. Different stages of content 134 While the contents of the newspaper do not change during the 135 newspaper distribution path from Newspaper Company all the way to 136 Newspaper Reader, the form the newspaper takes during the 137 distribution path does change. The Newspaper Company does not 138 directly create the final newspaper that Readers find on their 139 doorstep. What the Newspaper Company creates and delivers to the 140 Printing Company is a printing plate, a mastercopy, of the newspaper. 141 The Printing Company then uses this printing plate to create a number 142 of replicas (mastercopy replicas) to use in all of its printing 143 facilities. Based on these replicas, the actual newspapers (the 144 consumables) are printed. These printed newspapers are then 145 distributed by a network of trucks to one or more distribution 146 centers. How the newspapers end up in the hands of to the Newspaper 147 Reader depends on the preferences (and location) of that Reader. Some 148 Readers might pick it up at a Newsstand Company, while others will 149 have it delivered by a Postal Company. 151 A path similar to the one taken by the newspaper is also taken by a 152 piece of Content in the Content Delivery Network chain. The Content 153 Provider does not necessarily create the final piece of content, or 154 the form it takes, that is received by the End User. Along the way 155 the Content might be transcoded to use a different codec, repackaged 156 in a different video container, and delivered using different 157 transport mechanisms and protocols. 159 In some situations, it might be useful to be able to distinguish 160 between the different fases and forms content goes through in the 161 content delivery chain. For example, in the case of CDN 162 Interconnection: When talking about how an Upstream CDN ingests 163 content into a Downstream CDN, it is important to know what the term 164 'content' in this case means. Is it the content in the form as it was 165 first ingested into the Upstream CDN by the Content Provider? Or is 166 it the content in its multiple transcoded forms as stored on the 167 Upstream CDN? 169 The current terminology does not allow for distinguishing between 170 these different fases and forms of content in the content delivery 171 chain. 173 3. Content Terminology 175 As shown in the previous section, the term content might take on a 176 different meaning depending on which phase in the delivery chain one 177 is talking about. It would therefore be useful to create some 178 additional terminology to describe these different content phases. 179 What follows is a first attempt at describing the different forms of 180 content as found in a CDN. 182 Mastercopy: The content as it is delivered by the Content Provider to 183 the (Upstream) CDN during the Content Ingestion process. 185 Replica: The content as it is transferred between the Upstream CDN 186 and the Downstream CDN. 188 Consumable: The content as it is stored on a CDN delivery node 189 directly prior to being delivered to an End User. 191 Note that, depending on the agreed arrangements with the Content 192 Provider, a Consumable might be a repackaged or transcoded version 193 from the origal Mastercopy or Replica in order to make it suitable 194 for a specific type of end device. Furthermore, a Consumable might be 195 a single file or consist of multiple files/segments that are the 196 result of a segmentation operation having been performed on the 197 content, e.g. to allow for specific transport mechanisms such as HTTP 198 Adapative Streaming (HAS) to be used. 200 It should be noted that this terminology is purely meant for 201 indicating the role of a particular piece of content in a particular 202 situation; it does not mean that a Consumable and a Mastercopy cannot 203 be bit-for-bit equivalent. 205 4. IANA Considerations 206 This memo includes no request to IANA. 208 5. Security Considerations 210 This memo includes no security considerations. 212 6. Informative References 214 [I-D.bertrand-cdni-use-cases] 215 Bertrand, G., Stephan, E., Watson, G., Burbridge, T., and 216 P. Eardley, "Use Cases for Content Distribution Network 217 Interconnection", draft-bertrand-cdni-use-cases-01 (work 218 in progress), January 2011. 220 [I-D.jenkins-cdni-problem-statement] 221 Niven-Jenkins, B., Faucheur, F., and N. Bitar, "Content 222 Distribution Network Interconnection (CDNI) Problem 223 Statement", draft-jenkins-cdni-problem-statement-02 (work 224 in progress), March 2011. 226 [ETSI TS 102 990 v0.0.7] 227 ETSI MCD CDN-I Working Group, "Media Content Distribution 228 (MCD); Media CDN Interconnection, use cases and 229 requirements", http://docbox.etsi.org/MCD/Open/ 230 Latest_Drafts/ts_102990v000007p.pdf 232 Authors' Addresses 234 M. Oskar van Deventer 235 TNO 236 Brassersplein 2 237 Delft, 238 the Netherlands 240 Phone: +31 6 51 914 918 241 Email: oskar.vandeventer@tno.nl 243 Ray van Brandenburg 244 TNO 245 Brassersplein 2 246 Delft, 247 the Netherlands 249 Phone: +31 88 86 63609 250 Email: ray.vanbrandenburg@tno.nl