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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for intended status: Informational ---------------------------------------------------------------------------- == Outdated reference: A later version (-08) exists of draft-ietf-cdni-problem-statement-06 == Outdated reference: A later version (-17) exists of draft-ietf-cdni-requirements-03 -- Obsolete informational reference (is this intentional?): RFC 2818 (Obsoleted by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 Obsoletes: 3570 (if approved) France Telecom - Orange 5 Intended status: Informational T. Burbridge 6 Expires: December 13, 2012 P. Eardley 7 BT 8 K. Ma 9 Azuki Systems, Inc. 10 G. Watson 11 Alcatel-Lucent (Velocix) 12 June 11, 2012 14 Use Cases for Content Delivery Network Interconnection 15 draft-ietf-cdni-use-cases-07 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. It obsoletes RFC 3570. 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 December 13, 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 . . . . . . . . . . . . 9 73 3.2. Resiliency . . . . . . . . . . . . . . . . . . . . . . . . 9 74 3.2.1. Failure of Content Delivery Resources . . . . . . . . 9 75 3.2.2. Content Acquisition Resiliency . . . . . . . . . . . . 10 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 RFC 3570 described slightly different terminologies and models for 105 "Content Internetworking (CDI)". The present document obsoletes RFC 106 3570 to avoid confusion. 108 This document identifies the main motivations for a CDN Provider to 109 interconnect its CDN: 111 o CDN Footprint Extension Use Cases (Section 2) 113 o CDN Offload Use Cases (Section 3) 115 o CDN Capability Use Cases (Section 4) 117 Then, the document highlights the need for interoperability in order 118 to exchange and enforce content delivery policies (Section 5). 120 1.1. Terminology 122 We adopt the terminology described in 123 [I-D.ietf-cdni-problem-statement], and [I-D.davie-cdni-framework]. 125 We extend this terminology with the following terms. 127 Access CDN: 129 A CDN that includes Surrogates in the same administrative network as 130 the end-user. Such CDN can use accurate information on the End 131 User's network context to provide valued-added Content Delivery 132 Services to Content Service Providers. 134 1.2. Abbreviations 136 o CDN: Content Delivery Network also known as Content Distribution 137 Network 139 o CSP: Content Service Provider 141 o dCDN: downstream CDN 143 o DNS: Domain Name System 145 o DRM: Digital Rights Management 147 o EU: End User 149 o ISP: Internet Service Provider 151 o NSP: Network Service Provider 153 o QoE: Quality of Experience 155 o QoS: Quality of Service 157 o uCDN: upstream CDN 159 o URL: Uniform Resource Locator 161 o WiFi: Wireless Fidelity 163 1.3. Rationale for Multi-CDN Systems 165 Content Delivery Networks (CDNs) are used to deliver content because 166 they can: 168 o improve the experience for the End User; for instance delivery has 169 lower latency (decreased round-trip-time and higher throughput 170 between the user and the delivery server) and better robustness 171 (ability to use multiple delivery servers), 173 o reduce the network operator's costs; for instance, lower delivery 174 cost (reduced bandwidth usage) for cacheable content, 176 o reduce the Content Service Provider's (CSP) internal costs, such 177 as datacenter capacity, space, and electricity consumption, as 178 popular content is delivered externally through the CDN rather 179 than through the CSP's own servers. 181 Indeed, many Network Service Providers (NSPs) and enterprise service 182 providers are deploying or have deployed their own CDNs. Despite the 183 potential benefits of interconnecting CDNs, today each CDN is a 184 standalone network. The objective of CDN Interconnection is to 185 overcome this restriction: the interconnected CDNs should be able to 186 collectively behave as a single delivery infrastructure. 188 An example is depicted in Figure 1, where two CDN Providers establish 189 a CDN Interconnection. The Content Service Provider CSP-1 reaches an 190 agreement with CDN Provider 'A' for the delivery of its content. 191 Independently, CDN Provider 'A' and CDN Provider 'B' agree to 192 interconnect their CDNs. 194 When a given User Agent requests content from CSP-1, CDN-A may 195 consider that delivery by CDN-B is appropriate, for instance, because 196 CDN-B is an Access CDN and the user is directly attached to it. 197 Through the CDN Interconnection arrangements put in place between 198 CDN-A and CDN-B (as a result of the CDN Interconnection agreement 199 established between CDN Provider 'A' and CDN Provider 'B'), CDN-A can 200 redirect the request to CDN-B and the content is actually delivered 201 to the User Agent by CDN-B. 203 The End User benefits from this arrangement through a better Quality 204 of Experience (QoE), because the content is delivered from a nearby 205 Surrogate. CDN Provider 'A' benefits because it does not need to 206 deploy such an extensive CDN, whilst CDN Provider 'B' may receive 207 some compensation for the delivery. CSP-1 benefits because it only 208 needs to make one business agreement and one technical arrangement 209 with CDN Provider 'A', but its End Users get a service quality as 210 though CSP-1 had also gone to the trouble of making a business 211 agreement and technical arrangement with CDN Provider 'B'. 213 +-------+ +-------+ 214 | CSP-1 | | CSP-2 | 215 +-------+ +-------+ 216 | | 217 ,--,--,--./ ,--,--,--. 218 ,-' `-. ,-' `-. 219 (CDN Provider 'A')=====(CDN Provider 'B') 220 `-. (CDN-A) ,-' `-. (CDN-B) ,-' 221 `--'--'--' `--'--'--' 222 | 223 +------------+ 224 | User Agent | 225 +------------+ 226 === CDN Interconnection 228 Figure 1 230 To extend the example, another Content Service Provider, CSP-2, may 231 also reach an agreement with CDN Provider 'A'. However, CSP-2 may 232 not want its content to be distributed by CDN Provider B; for 233 example, CSP-2 may not have distribution rights in the country where 234 CDN Provider 'B' operates. This example illustrates that policy 235 considerations are an important part of CDNI. 237 2. Footprint Extension Use Cases 239 Footprint extension is expected to be a major use case for CDN 240 Interconnection. 242 2.1. Geographic Extension 244 In this use case, the CDN Provider wants to extend the geographic 245 distribution that it can offer to its CSPs: 247 o without compromising the quality of delivery, 249 o without incurring additional transit and other network costs that 250 would result from serving content from geographically or 251 topologically remote Surrogates, 253 o without incurring the cost of deploying and operating Surrogates 254 and the associated CDN infrastructure that may not be justified in 255 the corresponding geographic region (e.g., because of relatively 256 low delivery volume, or conversely because of the high investments 257 that would be needed to satisfy the high volume). 259 If there are several CDN Providers that have a geographically limited 260 footprint (e.g., restricted to one country), or do not serve all End 261 Users in a geographic area, then interconnecting their CDNs enables 262 these CDN Providers to provide their services beyond their own 263 footprint. 265 As an example, suppose a French CSP wants to distribute its TV 266 programs to End Users located in France and various countries in 267 North Africa. It asks a French CDN Provider to deliver the content. 268 The French CDN Provider's network only covers France, so it makes an 269 agreement with another CDN Provider that covers North Africa. 270 Overall, from the CSP's perspective the French CDN Provider provides 271 a CDN service for both France and North Africa. 273 In addition to video, this use case applies to other types of content 274 such as automatic software updates (browser updates, operating system 275 patches, virus database update, etc). 277 2.2. Inter-Affiliates Interconnection 279 The previous section describes the case of geographic extension 280 between CDNs operated by different entities. A large CDN Provider 281 may have several subsidiaries that also each operate their own CDN 282 (which may rely on different CDN technologies, see Section 4.2). In 283 certain circumstances, the CDN Provider needs to make these CDNs 284 interoperate to provide a consistent service to its customers on the 285 whole collective footprint. 287 2.3. ISP Handling of Third-Party Content 289 Consider an ISP carrying to its subscribers a lot of content that 290 comes from a third party CSP and that is injected into the ISP's 291 network by an Authoritative CDN Provider. There are mutual benefits 292 to the ISP (acting as an Access CDN), the Authoritative CDN, and the 293 CSP that would make a case for establishing a CDNI agreement. For 294 example: 296 o Allow the CSP to offer improved QoE and QoE services to 297 subscribers, for example, reduced content startup time or 298 increased video quality and resolution of adaptive streaming 299 content. 301 o Allow the Authoritative CDN to reduce hardware capacity and 302 footprint, by using the ISP caching and delivery capacity. 304 o Allow the ISP to reduce traffic load on some segments of the 305 network by caching inside of the ISP network. 307 o Allow the ISP to influence and/or control the traffic ingestion 308 points. 310 o Allow the ISP to derive some incremental revenue for transport of 311 the traffic and to monetize QoE services. 313 2.4. Nomadic Users 315 In this scenario, a CSP wishes to allow End Users who move between 316 access networks to continue to access their content. The motivation 317 of this case is to allow nomadic End Users to maintain access to 318 content with a consistent QoE, across a range of devices and/or 319 geographic regions. 321 This use case covers situations like: 323 o End Users moving between different access networks, which may be 324 located within the same geographic region or different geographic 325 regions, 327 o End Users switching between different devices or delivery 328 technologies, as discussed in Section 4. 330 Consider the following example, illustrated in Figure 2: End User A 331 has subscription to a broadband service from NSP A, her "home NSP". 332 NSP A hosts CDN-A. Ordinarily, when End User A accesses content via 333 NSP A (her "home NSP") the content is delivered from CDN-A, which in 334 this example is within NSP A's network. 336 However, while End User A is not connected to NSP A's network, for 337 example, because it is connected to a WiFi provider or mobile 338 network, End User A can also access the same content. In this case, 339 End User A may benefit from accessing the same content but delivered 340 by an alternate CDN (CDN-B), in this case, hosted in the network of 341 the WiFi or mobile provider (NSP B), rather than from CDN-A in NSP 342 A's network. 344 +-------+ 345 |Content| 346 +-------+ 347 | 348 ,--,--,--. ,--,--,--. 349 ,-' NSP A `-. ,-' NSP B `-. 350 ( (CDN-A) )=====( (CDN-B) ) 351 `-. ,-' `-. ,-' 352 `--'--'--' `--'--'--' 353 | | 354 +------------+ +---------------+ 355 + EU A (home)| | EU A (nomadic)| 356 +------------+ +---------------+ 357 === CDN Interconnection 359 Figure 2 361 The alternate CDN (CDN-B) is allowed to distribute the content of CSP 362 A to End User A; however, no other End Users in the region of CDN-B 363 are allowed to retrieve the content unless they too have such an 364 agreement for nomadic access to content. 366 Depending on CSP's content delivery policies (see Appendix A.1), a 367 user moving to a different geographic region may be subject to geo- 368 blocking content delivery restrictions. In this case, he/she may not 369 be allowed to access some pieces of content. 371 3. Offload Use Cases 372 3.1. Overload Handling and Dimensioning 374 A CDN is likely to be dimensioned to support an expected maximum 375 traffic load. However, unexpected spikes in content popularity 376 (flash crowd) may drive load beyond the expected peak. The prime 377 recurrent time peaks of content distribution may differ between two 378 CDNs. Taking advantage of the different traffic peak times, a CDN 379 may interconnect with another CDN to increase its effective capacity 380 during the peak of traffic. This brings dimensioning savings to the 381 CDNs as they can use the resources of each other during their 382 respective peaks of activity. 384 Offload also applies to planned situations where a CDN Provider needs 385 CDN capacity in a particular region during a short period of time. 386 For example, a CDN can offload traffic to another CDN during a 387 specific maintenance operation or for covering the distribution of a 388 special event. For instance, consider a TV-channel which has 389 exclusive distribution rights on a major event, such as a 390 celebrities' wedding, or a major sport competition. The CDNs that 391 the TV-channel uses for delivering the content related to this event 392 are likely to experience a flash crowd during the event and to need 393 offloading traffic, while other CDNs will support a more usual 394 traffic load and be able to handle the offloaded traffic. 396 In this use case, the Delivering CDN on which requests are offloaded 397 should be able to handle the offloaded requests. Therefore, the uCDN 398 might require information on the dCDNs to be aware of the amount of 399 traffic it can offload to every dCDN. 401 3.2. Resiliency 403 3.2.1. Failure of Content Delivery Resources 405 It is important for CDNs to be able to guarantee service continuity 406 during partial failures (e.g., failure of some Surrogates). In 407 partial failure scenarios, a CDN Provider has at least three options: 409 1. if possible, use internal mechanisms to redirect traffic on 410 surviving equipment, 412 2. depending on traffic management policies, forward some requests 413 to the CSP's origin servers, and 415 3. redirect some requests toward another CDN, which must be able to 416 serve the redirected requests. 418 The last option is a use case for CDNI. 420 3.2.2. Content Acquisition Resiliency 422 Source content acquisition may be handled in one of two ways: 424 o CSP origin, where a CDN acquires content directly from the CSP's 425 origin server, or 427 o CDN origin, where a downstream CDN acquires content from a 428 Surrogate within an upstream CDN. 430 The ability to support content acquisition resiliency, is an 431 important use case for interconnected CDNs. When the content 432 acquisition source fails, the CDN might switch to another content 433 acquisition source. Similarly, when several content acquisition 434 sources are available, a CDN might balance the load between these 435 multiple sources. 437 Though other server and/or DNS load balancing techniques may be 438 employed in the network, interconnected CDNs may have a better 439 understanding of origin server availability and be better equipped to 440 both distribute load between origin servers and attempt content 441 acquisition from alternate content sources when acquisition failures 442 occur. When normal content acquisition fails, a CDN may need to try 443 other content source options, e.g.: 445 o an upstream CDN may acquire content from an alternate CSP origin 446 server, 448 o a downstream CDN may acquire content from an alternate Surrogate 449 within an upstream CDN, 451 o a downstream CDN may acquire content from an alternate upstream 452 CDN, or 454 o a downstream CDN may acquire content directly from the CSP's 455 origin server. 457 Though content acquisition protocols are beyond the scope of CDNI, 458 the selection of content acquisition sources should be considered and 459 facilitated. 461 4. CDN Capability Use Cases 463 4.1. Device and Network Technology Extension 465 In this use case, the CDN Provider may have the right geographic 466 footprint, but may wish to extend the supported range of devices and 467 User Agents or the supported range of delivery technologies. In this 468 case, a CDN Provider may interconnect with a CDN that offers 469 services: 471 o that the CDN Provider is not willing to provide or, 473 o that its own CDN is not able to support. 475 The following examples illustrate this use case: 477 1. CDN-A cannot support a specific delivery protocol. For instance, 478 CDN-A may interconnect with CDN-B to serve a proportion of its 479 traffic that requires HTTPS [RFC2818]. CDN-A may use CDN-B's 480 footprint (which may overlap with its own) to deliver HTTPS 481 without needing to deploy its own infrastructure. This case 482 could also be true of other formats, delivery protocols (RTMP, 483 RTSP, etc.) and features (specific forms of authorization such as 484 tokens, per session encryption, etc.). 486 2. CDN-A has footprint covering traditional fixed line broadband and 487 wants to extend coverage to mobile devices. In this case, CDN-A 488 may contract and interconnect with CDN-B who has both: 490 * physical footprint inside the mobile network, 492 * the ability to deliver content over a protocol that is 493 required by specific mobile devices. 495 These cases can apply to many CDN features that a given CDN Provider 496 may not be able to support or not be willing to invest in, and thus, 497 that the CDN Provider would delegate to another CDN. 499 4.2. Technology and Vendor Interoperability 501 A CDN Provider may deploy a new CDN to run alongside its existing 502 CDN, as a simple way of migrating its CDN service to a new 503 technology. In addition, a CDN Provider may have a multi-vendor 504 strategy for its CDN deployment. Finally, a CDN Provider may want to 505 deploy a separate CDN for a particular CSP or a specific network. In 506 all these circumstances, CDNI benefits the CDN Provider, as it 507 simplifies or automates some inter-CDN operations (e.g., migrating 508 the request routing function progressively). 510 4.3. QoE and QoS Improvement 512 Some CSPs are willing to pay a premium for enhanced delivery of 513 content to their End Users. In some cases, even if the CDN Provider 514 could deliver the content to the End Users, it cannot meet the CSP's 515 service level requirements. As a result, the CDN Provider may 516 establish a CDN Interconnection agreement with another CDN Provider 517 that can provide the expected QoE to the End User, e.g., via an 518 Access CDN able to deliver content from Surrogates located closer to 519 the End User and with the required service level. 521 5. Enforcement of Content Delivery Policy 523 An important aspect common to all the above use cases is that CSPs 524 typically want to enforce content delivery policies. A CSP may want 525 to define content delivery policies that specify when, how, and/or to 526 whom the CDN delivers content. These policies apply to all 527 interconnected CDNs (uCDNs and dCDNs) in the same or similar way that 528 a CSP can define content delivery policies for content delivered by a 529 single, non-interconnected CDN. Appendix A provides examples of CSP 530 defined policies. 532 6. Acknowledgments 534 The authors would like to thank Kent Leung, Francois Le Faucheur, Ben 535 Niven-Jenkins, and Scott Wainner for lively discussions, as well as 536 for their reviews and comments on the mailing list. 538 They also thank the contributors of the EU FP7 OCEAN and ETICS 539 projects for valuable inputs. 541 7. IANA Considerations 543 This memo includes no request to IANA. 545 8. Security Considerations 547 This document focuses on the motivational use cases for CDN 548 Interconnection, and does not analyze the associated threats. Those 549 are discussed in [I-D.ietf-cdni-problem-statement]. 551 9. Informative References 553 [I-D.davie-cdni-framework] 554 Davie, B. and L. Peterson, "Framework for CDN 555 Interconnection", draft-davie-cdni-framework-01 (work in 556 progress), October 2011. 558 [I-D.ietf-cdni-problem-statement] 559 Niven-Jenkins, B., Faucheur, F., and N. Bitar, "Content 560 Distribution Network Interconnection (CDNI) Problem 561 Statement", draft-ietf-cdni-problem-statement-06 (work in 562 progress), May 2012. 564 [I-D.ietf-cdni-requirements] 565 Leung, K. and Y. Lee, "Content Distribution Network 566 Interconnection (CDNI) Requirements", 567 draft-ietf-cdni-requirements-03 (work in progress), 568 June 2012. 570 [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000. 572 Appendix A. Content Service Providers' Delivery Policies 574 CSPs commonly apply different delivery policies to given sets of 575 content assets delivered through CDNs. Interconnected CDNs need to 576 support these policies. This annex presents examples of CSPs' 577 delivery policies and their consequences on CDNI operations. 579 A.1. Content Delivery Policy Enforcement 581 The content distribution policies that a CSP attaches to a content 582 asset may depend on many criteria. For instance, distribution 583 policies for audiovisual content often combine constraints of varying 584 levels of complexity and sophistication, e.g.: 586 o temporal constraints (e.g., available for 24 hours, available 28 587 days after DVD release, etc.), 589 o user agent platform constraints (e.g., mobile device platforms, 590 desktop computer platforms, set-top-box platforms, etc.), 592 o resolution-based constraints (e.g., high definition vs. standard 593 definition encodings), 595 o user agent identification or authorization, 597 o access network constraints (e.g., per NSP), and 599 o geolocation-based constraints (e.g., per country). 601 CSPs may use sophisticated policies in accordance to their business 602 model. However, the enforcement of those policies does not 603 necessarily require that the delivery network understand the policy 604 rationales or how policies apply to specific content assets. Content 605 delivery policies may indeed be distilled into simple rules which can 606 be commonly enforced across all dCDNs. These rules may influence 607 dCDN delegation and Surrogate selection decisions, for instance, to 608 ensure that the specific rules (e.g. time-window, geo-blocking, pre- 609 authorization validation) can indeed be enforced by the delivering 610 CDN. In turn, this can guarantee to the CSP that content license 611 violations can be prevented, including prevention of premature access 612 to pre-positioned content or enforcement of geo-blocking policies. 614 +-----+ 615 | CSP | Policies driven by business (e.g., available 616 +-----+ only in UK and only from July 1st to September 1st) 617 \ 618 \ Translate policies into 619 \simple rules (e.g., provide an authorization token) 620 \ 621 V 622 +-----+ 623 | CDN | Apply simple rules (e.g., check an 624 +-----+ authorization token and enforce geoblocking) 625 \ 626 \ Distribute simple rules 627 V 628 +-----+ 629 | CDN | Apply simple rules 630 +-----+ 632 Figure 3 634 A.2. Secure Access 636 Many protocols exist for delivering content to End Users. CSPs may 637 dictate a specific protocol or set of protocols which are acceptable 638 for delivery of their content, especially in the case where content 639 protection or user authentication is required (e.g., must use HTTPS). 640 CSPs may also perform per-request authentication/authorization 641 decision and then have the CDNs enforce that decision (e.g., must 642 validate URL signing, etc.). 644 A.3. Branding 646 Preserving the branding of the CSP throughout delivery is often 647 important to the CSP. CSPs may desire to offer content services 648 under their own name, even when the associated CDN service involves 649 other CDN Providers. For instance, a CSP may desire to ensure that 650 content is delivered with URIs appearing to the End Users under the 651 CSP's own domain name, even when the content delivery involves 652 separate CDN Providers. The CSP may wish to prevent the delivery of 653 its content by specific dCDNs that lack support for such branding 654 preservation features. 656 Analogous cases exist when the uCDN wants to offer CDN services under 657 its own branding even if dCDNs are involved. Similarly, a CDN 658 Provider might wish to restrict the delivery delegation to a chain 659 that preserves its brand visibility. 661 Authors' Addresses 663 Gilles Bertrand (editor) 664 France Telecom - Orange 665 38-40 rue du General Leclerc 666 Issy les Moulineaux, 92130 667 FR 669 Phone: +33 1 45 29 89 46 670 Email: gilles.bertrand@orange.com 672 Stephan Emile 673 France Telecom - Orange 674 2 avenue Pierre Marzin 675 Lannion F-22307 676 France 678 Email: emile.stephan@orange.com 680 Trevor Burbridge 681 BT 682 B54 Room 70, Adastral Park, Martlesham 683 Ipswich, IP5 3RE 684 UK 686 Email: trevor.burbridge@bt.com 687 Philip Eardley 688 BT 689 B54 Room 77, Adastral Park, Martlesham 690 Ipswich, IP5 3RE 691 UK 693 Email: philip.eardley@bt.com 695 Kevin J. Ma 696 Azuki Systems, Inc. 697 43 Nagog Park 698 Acton, MA 01720 699 USA 701 Phone: +1 978-844-5100 702 Email: kevin.ma@azukisystems.com 704 Grant Watson 705 Alcatel-Lucent (Velocix) 706 3 Ely Road 707 Milton, Cambridge CB24 6AA 708 UK 710 Email: gwatson@velocix.com