idnits 2.17.1 draft-ietf-cdni-use-cases-06.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (May 24, 2012) is 4355 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: A later version (-08) exists of draft-ietf-cdni-problem-statement-06 == Outdated reference: A later version (-17) exists of draft-ietf-cdni-requirements-02 -- Obsolete informational reference (is this intentional?): RFC 2818 (Obsoleted by RFC 9110) Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Internet Engineering Task Force G. Bertrand, Ed. 3 Internet-Draft E. Stephan 4 Intended status: Informational France Telecom - Orange 5 Expires: November 25, 2012 T. Burbridge 6 P. Eardley 7 BT 8 K. Ma 9 Azuki Systems, Inc. 10 G. Watson 11 Alcatel-Lucent (Velocix) 12 May 24, 2012 14 Use Cases for Content Delivery Network Interconnection 15 draft-ietf-cdni-use-cases-06 17 Abstract 19 Content Delivery Networks (CDNs) are commonly used for improving the 20 End User experience of a content delivery service, at a reasonable 21 cost. This document focuses on use cases that correspond to 22 identified industry needs and that are expected to be realized once 23 open interfaces and protocols supporting interconnection of CDNs are 24 specified and implemented. The document can be used to guide the 25 definition of the requirements to be supported by CDN Interconnection 26 (CDNI) interfaces. 28 Status of this Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF). Note that other groups may also distribute 35 working documents as Internet-Drafts. The list of current Internet- 36 Drafts is at http://datatracker.ietf.org/drafts/current/. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 This Internet-Draft will expire on November 25, 2012. 45 Copyright Notice 47 Copyright (c) 2012 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (http://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the Simplified BSD License. 60 Table of Contents 62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 63 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 64 1.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3 65 1.3. Rationale for Multi-CDN Systems . . . . . . . . . . . . . 4 66 2. Footprint Extension Use Cases . . . . . . . . . . . . . . . . 6 67 2.1. Geographic Extension . . . . . . . . . . . . . . . . . . . 6 68 2.2. Inter-Affiliates Interconnection . . . . . . . . . . . . . 6 69 2.3. ISP Handling of Third-Party Content . . . . . . . . . . . 7 70 2.4. Nomadic Users . . . . . . . . . . . . . . . . . . . . . . 7 71 3. Offload Use Cases . . . . . . . . . . . . . . . . . . . . . . 8 72 3.1. Overload Handling and Dimensioning . . . . . . . . . . . . 8 73 3.2. Resiliency . . . . . . . . . . . . . . . . . . . . . . . . 9 74 3.2.1. Failure of Content Delivery Resources . . . . . . . . 9 75 3.2.2. Content Acquisition Resiliency . . . . . . . . . . . . 9 76 4. CDN Capability Use Cases . . . . . . . . . . . . . . . . . . . 10 77 4.1. Device and Network Technology Extension . . . . . . . . . 10 78 4.2. Technology and Vendor Interoperability . . . . . . . . . . 11 79 4.3. QoE and QoS Improvement . . . . . . . . . . . . . . . . . 11 80 5. Enforcement of Content Delivery Policy . . . . . . . . . . . . 12 81 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 82 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 83 8. Security Considerations . . . . . . . . . . . . . . . . . . . 12 84 9. Informative References . . . . . . . . . . . . . . . . . . . . 12 85 Appendix A. Content Service Providers' Delivery Policies . . . . 13 86 A.1. Content Delivery Policy Enforcement . . . . . . . . . . . 13 87 A.2. Secure Access . . . . . . . . . . . . . . . . . . . . . . 14 88 A.3. Branding . . . . . . . . . . . . . . . . . . . . . . . . . 14 89 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15 91 1. Introduction 93 Content Delivery Networks (CDNs) are commonly used for improving the 94 End User experience of a content delivery service, at a reasonable 95 cost. This document focuses on use cases that correspond to 96 identified industry needs and that are expected to be realized once 97 open interfaces and protocols supporting interconnection of CDNs are 98 specified and implemented. The document can be used to guide the 99 definition of the requirements (as documented in 100 [I-D.ietf-cdni-requirements]) to be supported by the set of CDN 101 Interconnection (CDNI) interfaces defined in 102 [I-D.ietf-cdni-problem-statement]. 104 This document identifies the main motivations for a CDN Provider to 105 interconnect its CDN: 107 o CDN Footprint Extension Use Cases (Section 2) 109 o CDN Offload Use Cases (Section 3) 111 o CDN Capability Use Cases (Section 4) 113 Then, the document highlights the need for interoperability in order 114 to exchange and enforce content delivery policies (Section 5). 116 1.1. Terminology 118 We adopt the terminology described in 119 [I-D.ietf-cdni-problem-statement], and [I-D.davie-cdni-framework]. 121 We extend this terminology with the following terms. 123 Access CDN: 125 A CDN that includes Surrogates in the same administrative network as 126 the end-user. Such CDN can use accurate information on the End 127 User's network context to provide valued-added Content Delivery 128 Services to Content Service Providers. 130 1.2. Abbreviations 132 o CDN: Content Delivery Network also known as Content Distribution 133 Network 135 o CSP: Content Service Provider 137 o dCDN: downstream CDN 138 o DNS: Domain Name System 140 o DRM: Digital Rights Management 142 o EU: End User 144 o ISP: Internet Service Provider 146 o NSP: Network Service Provider 148 o QoE: Quality of Experience 150 o QoS: Quality of Service 152 o uCDN: upstream CDN 154 o URL: Uniform Resource Locator 156 o WiFi: Wireless Fidelity 158 1.3. Rationale for Multi-CDN Systems 160 Content Delivery Networks (CDNs) are used to deliver content because 161 they can: 163 o improve the experience for the End User; for instance delivery has 164 lower latency (decreased round-trip-time and higher throughput 165 between the user and the delivery server) and better robustness 166 (ability to use multiple delivery servers), 168 o reduce the network operator's costs; for instance, lower delivery 169 cost (reduced bandwidth usage) for cacheable content, 171 o reduce the Content Service Provider's (CSP) internal costs, such 172 as datacenter capacity, space, and electricity consumption, as 173 popular content is delivered externally through the CDN rather 174 than through the CSP's own servers. 176 Indeed, many Network Service Providers (NSPs) and enterprise service 177 providers are deploying or have deployed their own CDNs. Despite the 178 potential benefits of interconnecting CDNs, today each CDN is a 179 standalone network. The objective of CDN Interconnection is to 180 overcome this restriction: the interconnected CDNs should be able to 181 collectively behave as a single delivery infrastructure. 183 An example is depicted in Figure 1, where two CDN Providers establish 184 a CDN Interconnection. The Content Service Provider CSP-1 reaches an 185 agreement with CDN Provider 'A' for the delivery of its content. 187 Independently, CDN Provider 'A' and CDN Provider 'B' agree to 188 interconnect their CDNs. 190 When a given User Agent requests content from CSP-1, CDN-A may 191 consider that delivery by CDN-B is appropriate, for instance, because 192 CDN-B is an Access CDN and the user is directly attached to it. 193 Through the CDN Interconnection arrangements put in place between 194 CDN-A and CDN-B (as a result of the CDN Interconnection agreement 195 established between CDN Provider 'A' and CDN Provider 'B'), CDN-A can 196 redirect the request to CDN-B and the content is actually delivered 197 to the User Agent by CDN-B. 199 The End User benefits from this arrangement through a better Quality 200 of Experience (QoE), because the content is delivered from a nearby 201 Surrogate. CDN Provider 'A' benefits because it does not need to 202 deploy such an extensive CDN, whilst CDN Provider 'B' may receive 203 some compensation for the delivery. CSP-1 benefits because it only 204 needs to make one business agreement and one technical arrangement 205 with CDN Provider 'A', but its End Users get a service quality as 206 though CSP-1 had also gone to the trouble of making a business 207 agreement and technical arrangement with CDN Provider 'B'. 209 +-------+ +-------+ 210 | CSP-1 | | CSP-2 | 211 +-------+ +-------+ 212 | | 213 ,--,--,--./ ,--,--,--. 214 ,-' `-. ,-' `-. 215 (CDN Provider 'A')=====(CDN Provider 'B') 216 `-. (CDN-A) ,-' `-. (CDN-B) ,-' 217 `--'--'--' `--'--'--' 218 | 219 +------------+ 220 | User Agent | 221 +------------+ 222 === CDN Interconnection 224 Figure 1 226 To extend the example, another Content Service Provider, CSP-2, may 227 also reach an agreement with CDN Provider 'A'. However, CSP-2 may 228 not want its content to be distributed by CDN Provider B; for 229 example, CSP-2 may not have distribution rights in the country where 230 CDN Provider 'B' operates. This example illustrates that policy 231 considerations are an important part of CDNI. 233 2. Footprint Extension Use Cases 235 Footprint extension is expected to be a major use case for CDN 236 Interconnection. 238 2.1. Geographic Extension 240 In this use case, the CDN Provider wants to extend the geographic 241 distribution that it can offer to its CSPs: 243 o without compromising the quality of delivery, 245 o without incurring additional transit and other network costs that 246 would result from serving content from geographically or 247 topologically remote Surrogates, 249 o without incurring the cost of deploying and operating Surrogates 250 and the associated CDN infrastructure that may not be justified in 251 the corresponding geographic region (e.g., because of relatively 252 low delivery volume, or conversely because of the high investments 253 that would be needed to satisfy the high volume). 255 If there are several CDN Providers that have a geographically limited 256 footprint (e.g., restricted to one country), or do not serve all End 257 Users in a geographic area, then interconnecting their CDNs enables 258 these CDN Providers to provide their services beyond their own 259 footprint. 261 As an example, suppose a French CSP wants to distribute its TV 262 programs to End Users located in France and various countries in 263 North Africa. It asks a French CDN Provider to deliver the content. 264 The French CDN Provider's network only covers France, so it makes an 265 agreement with another CDN Provider that covers North Africa. 266 Overall, from the CSP's perspective the French CDN Provider provides 267 a CDN service for both France and North Africa. 269 In addition to video, this use case applies to other types of content 270 such as automatic software updates (browser updates, operating system 271 patches, virus database update, etc). 273 2.2. Inter-Affiliates Interconnection 275 The previous section describes the case of geographic extension 276 between CDNs operated by different entities. A large CDN Provider 277 may have several subsidiaries that also each operate their own CDN 278 (which may rely on different CDN technologies, see Section 4.2). In 279 certain circumstances, the CDN Provider needs to make these CDNs 280 interoperate to provide a consistent service to its customers on the 281 whole collective footprint. 283 2.3. ISP Handling of Third-Party Content 285 Consider an ISP carrying to its subscribers a lot of content that 286 comes from a third party CSP and that is injected into the ISP's 287 network by an Authoritative CDN Provider. There are mutual benefits 288 to the ISP (acting as an Access CDN), the Authoritative CDN, and the 289 CSP that would make a case for establishing a CDNI agreement. For 290 example: 292 o Allow the CSP to offer improved QoE and QoE services to 293 subscribers, for example, reduced content startup time or 294 increased video quality and resolution of adaptive streaming 295 content. 297 o Allow the Authoritative CDN to reduce hardware capacity and 298 footprint, by using the ISP caching and delivery capacity. 300 o Allow the ISP to reduce traffic load on some segments of the 301 network by caching inside of the ISP network. 303 o Allow the ISP to influence and/or control the traffic ingestion 304 points. 306 o Allow the ISP to derive some incremental revenue for transport of 307 the traffic and to monetize QoE services. 309 2.4. Nomadic Users 311 In this scenario, a CSP wishes to allow End Users who move between 312 access networks to continue to access their content. The motivation 313 of this case is to allow nomadic End Users to maintain access to 314 content with a consistent QoE, across a range of devices and/or 315 geographic regions. 317 This use case covers situations like: 319 o End Users moving between different access networks, which may be 320 located within the same geographic region or different geographic 321 regions, 323 o End Users switching between different devices or delivery 324 technologies, as discussed in Section 4. 326 Consider the following example, illustrated in Figure 2: End User A 327 has subscription to a broadband service from NSP A, her "home NSP". 328 NSP A hosts CDN-A. Ordinarily, when End User A accesses content via 329 NSP A (her "home NSP") the content is delivered from CDN-A, which in 330 this example is within NSP A's network. 332 However, while End User A is not connected to NSP A's network, for 333 example, because it is connected to a WiFi provider or mobile 334 network, End User A can also access the same content. In this case, 335 End User A may benefit from accessing the same content but delivered 336 by an alternate CDN (CDN-B), in this case, hosted in the network of 337 the WiFi or mobile provider (NSP B), rather than from CDN-A in NSP 338 A's network. 340 +-------+ 341 |Content| 342 +-------+ 343 | 344 ,--,--,--. ,--,--,--. 345 ,-' NSP A `-. ,-' NSP B `-. 346 ( (CDN-A) )=====( (CDN-B) ) 347 `-. ,-' `-. ,-' 348 `--'--'--' `--'--'--' 349 | | 350 +------------+ +---------------+ 351 + EU A (home)| | EU A (nomadic)| 352 +------------+ +---------------+ 353 === CDN Interconnection 355 Figure 2 357 The alternate CDN (CDN-B) is allowed to distribute the content of CSP 358 A to End User A; however, no other End Users in the region of CDN-B 359 are allowed to retrieve the content unless they too have such an 360 agreement for nomadic access to content. 362 Depending on CSP's content delivery policies (see Appendix A.1), a 363 user moving to a different geographic region may be subject to geo- 364 blocking content delivery restrictions. In this case, he/she may not 365 be allowed to access some pieces of content. 367 3. Offload Use Cases 369 3.1. Overload Handling and Dimensioning 371 A CDN is likely to be dimensioned to support an expected maximum 372 traffic load. However, unexpected spikes in content popularity 373 (flash crowd) may drive load beyond the expected peak. The prime 374 recurrent time peaks of content distribution may differ between two 375 CDNs. Taking advantage of the different traffic peak times, a CDN 376 may interconnect with another CDN to increase its effective capacity 377 during the peak of traffic. This brings dimensioning savings to the 378 CDNs as they can use the resources of each other during their 379 respective peaks of activity. 381 Offload also applies to planned situations where a CDN Provider needs 382 CDN capacity in a particular region during a short period of time. 383 For example, a CDN can offload traffic to another CDN during a 384 specific maintenance operation or for covering the distribution of a 385 special event. For instance, consider a TV-channel which has 386 exclusive distribution rights on a major event, such as a 387 celebrities' wedding, or a major sport competition. The CDNs that 388 the TV-channel uses for delivering the content related to this event 389 are likely to experience a flash crowd during the event and to need 390 offloading traffic, while other CDNs will support a more usual 391 traffic load and be able to handle the offloaded traffic. 393 In this use case, the Delivering CDN on which requests are offloaded 394 should be able to handle the offloaded requests. Therefore, the uCDN 395 might require information on the dCDNs to be aware of the amount of 396 traffic it can offload to every dCDN. 398 3.2. Resiliency 400 3.2.1. Failure of Content Delivery Resources 402 It is important for CDNs to be able to guarantee service continuity 403 during partial failures (e.g., failure of some Surrogates). In 404 partial failure scenarios, a CDN Provider has at least three options: 406 1. if possible, use internal mechanisms to redirect traffic on 407 surviving equipment, 409 2. depending on traffic management policies, forward some requests 410 to the CSP's origin servers, and 412 3. redirect some requests toward another CDN, which must be able to 413 serve the redirected requests. 415 The last option is a use case for CDNI. 417 3.2.2. Content Acquisition Resiliency 419 Source content acquisition may be handled in one of two ways: 421 o CSP origin, where a CDN acquires content directly from the CSP's 422 origin server, or 424 o CDN origin, where a downstream CDN acquires content from a 425 Surrogate within an upstream CDN. 427 The ability to support content acquisition resiliency, is an 428 important use case for interconnected CDNs. When the content 429 acquisition source fails, the CDN might switch to another content 430 acquisition source. Similarly, when several content acquisition 431 sources are available, a CDN might balance the load between these 432 multiple sources. 434 Though other server and/or DNS load balancing techniques may be 435 employed in the network, interconnected CDNs may have a better 436 understanding of origin server availability and be better equipped to 437 both distribute load between origin servers and attempt content 438 acquisition from alternate content sources when acquisition failures 439 occur. When normal content acquisition fails, a CDN may need to try 440 other content source options, e.g.: 442 o an upstream CDN may acquire content from an alternate CSP origin 443 server, 445 o a downstream CDN may acquire content from an alternate Surrogate 446 within an upstream CDN, 448 o a downstream CDN may acquire content from an alternate upstream 449 CDN, or 451 o a downstream CDN may acquire content directly from the CSP's 452 origin server. 454 Though content acquisition protocols are beyond the scope of CDNI, 455 the selection of content acquisition sources should be considered and 456 facilitated. 458 4. CDN Capability Use Cases 460 4.1. Device and Network Technology Extension 462 In this use case, the CDN Provider may have the right geographic 463 footprint, but may wish to extend the supported range of devices and 464 User Agents or the supported range of delivery technologies. In this 465 case, a CDN Provider may interconnect with a CDN that offers 466 services: 468 o that the CDN Provider is not willing to provide or, 470 o that its own CDN is not able to support. 472 The following examples illustrate this use case: 474 1. CDN-A cannot support a specific delivery protocol. For instance, 475 CDN-A may interconnect with CDN-B to serve a proportion of its 476 traffic that requires HTTPS [RFC2818]. CDN-A may use CDN-B's 477 footprint (which may overlap with its own) to deliver HTTPS 478 without needing to deploy its own infrastructure. This case 479 could also be true of other formats, delivery protocols (RTMP, 480 RTSP, etc.) and features (specific forms of authorization such as 481 tokens, per session encryption, etc.). 483 2. CDN-A has footprint covering traditional fixed line broadband and 484 wants to extend coverage to mobile devices. In this case, CDN-A 485 may contract and interconnect with CDN-B who has both: 487 * physical footprint inside the mobile network, 489 * the ability to deliver content over a protocol that is 490 required by specific mobile devices. 492 These cases can apply to many CDN features that a given CDN Provider 493 may not be able to support or not be willing to invest in, and thus, 494 that the CDN Provider would delegate to another CDN. 496 4.2. Technology and Vendor Interoperability 498 A CDN Provider may deploy a new CDN to run alongside its existing 499 CDN, as a simple way of migrating its CDN service to a new 500 technology. In addition, a CDN Provider may have a multi-vendor 501 strategy for its CDN deployment. Finally, a CDN Provider may want to 502 deploy a separate CDN for a particular CSP or a specific network. In 503 all these circumstances, CDNI benefits the CDN Provider, as it 504 simplifies or automates some inter-CDN operations (e.g., migrating 505 the request routing function progressively). 507 4.3. QoE and QoS Improvement 509 Some CSPs are willing to pay a premium for enhanced delivery of 510 content to their End Users. In some cases, even if the CDN Provider 511 could deliver the content to the End Users, it cannot meet the CSP's 512 service level requirements. As a result, the CDN Provider may 513 establish a CDN Interconnection agreement with another CDN Provider 514 that can provide the expected QoE to the End User, e.g., via an 515 Access CDN able to deliver content from Surrogates located closer to 516 the End User and with the required service level. 518 5. Enforcement of Content Delivery Policy 520 An important aspect common to all the above use cases is that CSPs 521 typically want to enforce content delivery policies. A CSP may want 522 to define content delivery policies that specify when, how, and/or to 523 whom the CDN delivers content. These policies apply to all 524 interconnected CDNs (uCDNs and dCDNs) in the same or similar way that 525 a CSP can define content delivery policies for content delivered by a 526 single, non-interconnected CDN. Appendix A provides examples of CSP 527 defined policies. 529 6. Acknowledgments 531 The authors would like to thank Kent Leung, Francois Le Faucheur, Ben 532 Niven-Jenkins, and Scott Wainner for lively discussions, as well as 533 for their reviews and comments on the mailing list. 535 They also thank the contributors of the EU FP7 OCEAN and ETICS 536 projects for valuable inputs. 538 7. IANA Considerations 540 This memo includes no request to IANA. 542 8. Security Considerations 544 This document focuses on the motivational use cases for CDN 545 Interconnection, and does not analyze the associated threats. Those 546 are discussed in [I-D.ietf-cdni-problem-statement]. 548 9. Informative References 550 [I-D.davie-cdni-framework] 551 Davie, B. and L. Peterson, "Framework for CDN 552 Interconnection", draft-davie-cdni-framework-01 (work in 553 progress), October 2011. 555 [I-D.ietf-cdni-problem-statement] 556 Niven-Jenkins, B., Faucheur, F., and N. Bitar, "Content 557 Distribution Network Interconnection (CDNI) Problem 558 Statement", draft-ietf-cdni-problem-statement-06 (work in 559 progress), May 2012. 561 [I-D.ietf-cdni-requirements] 562 Leung, K. and Y. Lee, "Content Distribution Network 563 Interconnection (CDNI) Requirements", 564 draft-ietf-cdni-requirements-02 (work in progress), 565 December 2011. 567 [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000. 569 Appendix A. Content Service Providers' Delivery Policies 571 CSPs commonly apply different delivery policies to given sets of 572 content assets delivered through CDNs. Interconnected CDNs need to 573 support these policies. This annex presents examples of CSPs' 574 delivery policies and their consequences on CDNI operations. 576 A.1. Content Delivery Policy Enforcement 578 The content distribution policies that a CSP attaches to a content 579 asset may depend on many criteria. For instance, distribution 580 policies for audiovisual content often combine constraints of varying 581 levels of complexity and sophistication, e.g.: 583 o temporal constraints (e.g., available for 24 hours, available 28 584 days after DVD release, etc.), 586 o user agent platform constraints (e.g., mobile device platforms, 587 desktop computer platforms, set-top-box platforms, etc.), 589 o resolution-based constraints (e.g., high definition vs. standard 590 definition encodings), 592 o user agent identification or authorization, 594 o access network constraints (e.g., per NSP), and 596 o geolocation-based constraints (e.g., per country). 598 CSPs may use sophisticated policies in accordance to their business 599 model. However, the enforcement of those policies does not 600 necessarily require that the delivery network understand the policy 601 rationales or how policies apply to specific content assets. Content 602 delivery policies may indeed be distilled into simple rules which can 603 be commonly enforced across all dCDNs. These rules may influence 604 dCDN delegation and Surrogate selection decisions, for instance, to 605 ensure that the specific rules (e.g. time-window, geo-blocking, pre- 606 authorization validation) can indeed be enforced by the delivering 607 CDN. In turn, this can guarantee to the CSP that content license 608 violations can be prevented, including prevention of premature access 609 to pre-positioned content or enforcement of geo-blocking policies. 611 +-----+ 612 | CSP | Policies driven by business (e.g., available 613 +-----+ only in UK and only from July 1st to September 1st) 614 \ 615 \ Translate policies into 616 \simple rules (e.g., provide an authorization token) 617 \ 618 V 619 +-----+ 620 | CDN | Apply simple rules (e.g., check an 621 +-----+ authorization token and enforce geoblocking) 622 \ 623 \ Distribute simple rules 624 V 625 +-----+ 626 | CDN | Apply simple rules 627 +-----+ 629 Figure 3 631 A.2. Secure Access 633 Many protocols exist for delivering content to End Users. CSPs may 634 dictate a specific protocol or set of protocols which are acceptable 635 for delivery of their content, especially in the case where content 636 protection or user authentication is required (e.g., must use HTTPS). 637 CSPs may also perform per-request authentication/authorization 638 decision and then have the CDNs enforce that decision (e.g., must 639 validate URL signing, etc.). 641 A.3. Branding 643 Preserving the branding of the CSP throughout delivery is often 644 important to the CSP. CSPs may desire to offer content services 645 under their own name, even when the associated CDN service involves 646 other CDN Providers. For instance, a CSP may desire to ensure that 647 content is delivered with URIs appearing to the End Users under the 648 CSP's own domain name, even when the content delivery involves 649 separate CDN Providers. The CSP may wish to prevent the delivery of 650 its content by specific dCDNs that lack support for such branding 651 preservation features. 653 Analogous cases exist when the uCDN wants to offer CDN services under 654 its own branding even if dCDNs are involved. Similarly, a CDN 655 Provider might wish to restrict the delivery delegation to a chain 656 that preserves its brand visibility. 658 Authors' Addresses 660 Gilles Bertrand (editor) 661 France Telecom - Orange 662 38-40 rue du General Leclerc 663 Issy les Moulineaux, 92130 664 FR 666 Phone: +33 1 45 29 89 46 667 Email: gilles.bertrand@orange.com 669 Stephan Emile 670 France Telecom - Orange 671 2 avenue Pierre Marzin 672 Lannion F-22307 673 France 675 Email: emile.stephan@orange.com 677 Trevor Burbridge 678 BT 679 B54 Room 70, Adastral Park, Martlesham 680 Ipswich, IP5 3RE 681 UK 683 Email: trevor.burbridge@bt.com 685 Philip Eardley 686 BT 687 B54 Room 77, Adastral Park, Martlesham 688 Ipswich, IP5 3RE 689 UK 691 Email: philip.eardley@bt.com 692 Kevin J. Ma 693 Azuki Systems, Inc. 694 43 Nagog Park 695 Acton, MA 01720 696 USA 698 Phone: +1 978-844-5100 699 Email: kevin.ma@azukisystems.com 701 Grant Watson 702 Alcatel-Lucent (Velocix) 703 3 Ely Road 704 Milton, Cambridge CB24 6AA 705 UK 707 Email: gwatson@velocix.com