1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T Y.2084 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (06/2015) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Next Generation Networks Frameworks and functional archite
2、cture models Distributed service networking content distribution functions Recommendation ITU-T Y.2084 ITU-T Y-SERIES RECOMMENDATIONS GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS GLOBAL INFORMATION INFRASTRUCTURE General Y.100Y.199 Services, applications
3、and middleware Y.200Y.299 Network aspects Y.300Y.399 Interfaces and protocols Y.400Y.499 Numbering, addressing and naming Y.500Y.599 Operation, administration and maintenance Y.600Y.699 Security Y.700Y.799 Performances Y.800Y.899 INTERNET PROTOCOL ASPECTS General Y.1000Y.1099 Services and applicatio
4、ns Y.1100Y.1199 Architecture, access, network capabilities and resource management Y.1200Y.1299 Transport Y.1300Y.1399 Interworking Y.1400Y.1499 Quality of service and network performance Y.1500Y.1599 Signalling Y.1600Y.1699 Operation, administration and maintenance Y.1700Y.1799 Charging Y.1800Y.189
5、9 IPTV over NGN Y.1900Y.1999 NEXT GENERATION NETWORKS Frameworks and functional architecture models Y.2000Y.2099 Quality of Service and performance Y.2100Y.2199 Service aspects: Service capabilities and service architecture Y.2200Y.2249 Service aspects: Interoperability of services and networks in N
6、GN Y.2250Y.2299 Enhancements to NGN Y.2300Y.2399 Network management Y.2400Y.2499 Network control architectures and protocols Y.2500Y.2599 Packet-based Networks Y.2600Y.2699 Security Y.2700Y.2799 Generalized mobility Y.2800Y.2899 Carrier grade open environment Y.2900Y.2999 FUTURE NETWORKS Y.3000Y.349
7、9 CLOUD COMPUTING Y.3500Y.3999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T Y.2084 (06/2015) i Recommendation ITU-T Y.2084 Distributed service networking content distribution functions Summary Recommendation ITU-T Y.2084 specifies the functions for distributed s
8、ervice networking (DSN) content distribution functions (CDFs), taking into account the requirements and capabilities for DSN as described in Recommendation ITU-T Y.2206 and the architecture for DSN as described in Recommendation ITU-T Y.2080. The main objective of this Recommendation is to provide g
9、uidance regarding the design of content-oriented services and applications making use of DSN CDF. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T Y.2084 2015-06-13 13 11.1002/1000/12511 Keywords CDF, content distribution function, distributed service networking, DSN, functio
10、nal description, information flows, reference point. _ * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T Y.2084 (06/2015) FOREW
11、ORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying
12、technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups wh
13、ich, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO an
14、d IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (t
15、o ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such word
16、s does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position conce
17、rning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by pa
18、tents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2015 All rights reserved. No part of this pub
19、lication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T Y.2084 (06/2015) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 1 3.1 Terms defined elsewhere 1 3.2 Terms defined in this Recommendation . 2 4 Abbreviation and acronyms
20、 2 5 Conventions 3 6 Functional description of DSN CDF 3 6.1 CDF functions 3 6.2 Reference points . 4 6.3 Information flows . 5 7 Security considerations . 10 Appendix I Detailed functional entity description of CDF . 11 I.1 Functional architecture of CDF 11 I.2 Functional entities of CDF . 12 I.3 R
21、eference points and interfaces 13 Appendix II Use cases of DSN CDF and information flow for different scenarios . 14 II.1 Traditional cache 14 II.2 Traditional CDN . 16 II.3 P2P cache 21 II.4 P2P CDN 27 II.5 Integration . 29 Bibliography. 31 Rec. ITU-T Y.2084 (06/2015) 1 Recommendation ITU-T Y.2084
22、Distributed service networking content distribution functions 1 Scope This Recommendation specifies the distributed service networking (DSN) content distribution functions (CDFs) in detail, including: the detail functions of DSN CDF; the description of reference points related to DSN CDF; the inform
23、ation flow related to DSN CDF. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other re
24、ferences are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The referen
25、ce to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T Y.1910 Recommendation ITU-T Y.1910 (2008), IPTV functional architecture. ITU-T Y.2012 Recommendation ITU-T Y.2012 (2010), Functional requirements and architecture of next ge
26、neration networks. ITU-T Y.2019 Recommendation ITU-T Y.2019 (2010), Content delivery functional architecture in NGN. ITU-T Y.2080 Recommendation ITU-T Y.2080 (2012), Functional architecture for distributed service networking. ITU-T Y.2206 Recommendation ITU-T Y.2206 (2010), Requirements for distribu
27、ted service networking capabilities. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 buffer map ITU-T Y.2080: A map indicating the availability of chunks which can be shared with other DSN nodes. 3.1.2 chunk ITU-T Y.2080: A basic unit o
28、f data resulting from partitioning a content file into defined component parts. A DSN node may use a chunk as a unit of storage, advertisement and exchange among peers. 3.1.3 content node b-ITU-T Y Suppl.10: A DSN node which can be used for the media content distribution, storage and/or caching, etc
29、. 3.1.4 distributed service networking ITU-T Y.2206: An overlay network which provides distributed and manageable capabilities to support various multimedia services. 3.1.5 DSN node ITU-T Y.2206: A node used in DSN providing distributed functionalities, including distributed routing and distributed
30、storage. 2 Rec. ITU-T Y.2084 (06/2015) 3.1.6 functional entity ITU-T Y.2012: An entity that comprises an indivisible set of specific functions. Functional entities are logical concepts, while groupings of functional entities are used to describe practical, physical implementations. 3.1.7 video on de
31、mand (VoD) ITU-T Y.1910: A service in which the end user can, on demand, select and view video content and where the end user can control the temporal order in which the video content is viewed (e.g., the ability to start the viewing, pause, fast forward, rewind). 3.2 Terms defined in this Recommend
32、ation This Recommendation defines the following terms: 3.2.1 cache: A device that has been set up to store content (e.g., web pages, files, videos and audios) that has been accessed by users on a network. A user trying to access content that has already been stored on the cache will be sent the stor
33、ed version instead of downloading the content from the content source again. 3.2.2 content delivery network: A content delivery network (CDN) is a system of distributed servers that deliver content (e.g., web pages, files, videos and audios) to users based on pre-defined criteria such as the geograp
34、hic locations of users, the status of the content delivery server and the IP network connection. 3.2.3 live streaming: A video service in which a continuous stream flows in real time from the service provider to the terminal device and the user cannot control the temporal order in which content is p
35、layed. 3.2.4 P2P cache: A computer or network device that has been set up to store peer-to-peer (P2P) content (e.g., file chunks, video chunks, audio chunks) that is popular and has been accessed by users. It works similar to cache. The only difference is that P2P cache supports P2P protocol and ser
36、ves P2P content. Sometimes, cache and P2P cache could be co-located in the same device. 3.2.5 P2P CDN: The content delivery network (CDN) in which content is delivered in the mode of P2P; the delivery may be from CDN server to users or from CDN servers to CDN servers. NOTE Delivering in the mode of
37、P2P means that the content is sliced into chunks, and the copies of the chunks are stored in multiple CDN servers. Users or CDN servers can download chunks of the content from multiple CDN servers. 4 Abbreviation and acronyms This Recommendation uses the following abbreviations and acronyms: CDF Con
38、tent Distribution Function CDN Content Delivery Network CP Content Provider CP-FE Content Processing Functional Entity CSAF Content Service Application Function CS-FE Cache/Storage Functional Entity DBC-FE Distribution Control Functional Entity DD-FE Distribution and Delivery Functional Entity DLC-F
39、E Delivery Control Functional Entity DSN Distributed Service Networking EF End-user Function Rec. ITU-T Y.2084 (06/2015) 3 ER-FE Error Recovery Functional Entity FE Functional Entity GSLB Global Server Load Balancer ISP Internet Service Provider MF Management Function P2P Peer-to-Peer RLF Resource L
40、ocation Function SLB Server Load Balancer SP Service Provider TOCF Traffic Optimization Control Function UE User Equipment UGC User Generated Content URL Uniform Resource Locator VoD Video on Demand 5 Conventions In this Recommendation the following conventions apply: 1) The meaning of functions is
41、as follows: Functions: In the context of DSN content distribution function, “Functions“ are defined as a functional group composed of functional entities and is represented by the following symbol: 2) DSN network means the network constructed based on DSN. 6 Functional description of DSN CDF This cl
42、ause describes the CDF functions, reference points related to CDF, and typical information flows. 6.1 CDF functions CDF mainly performs the following functions: 1) Content ingestion DSN CDF supports automatic and manual content ingestion from the content service application function (CSAF). 2) Conte
43、nt cache/store DSN CDF supports storing content in the form of chunks. DSN CDF supports time-to-live for stored content. 4 Rec. ITU-T Y.2084 (06/2015) NOTE 1 Some content stored by CDF may be available only within a certain window of time. Providing a time-to-live value for stored data can reduce ma
44、nagement overhead by avoiding “delete“ commands sent to CDF storage. DSN CDF supports deletion of stored content. NOTE 2 A DSN node should be able to explicitly remove particular content (e.g., expired content). 3) Content processing DSN CDF supports content chunking and reassembly of chunks. DSN CD
45、F supports content pre-processing before content distribution. NOTE 3 DSN CDF may perform content adaptation for different types of terminals and network environments. 4) Content transmission DSN CDF enables the content to be transferred in the form of chunks. DSN CDF supports buffer map exchanges b
46、etween other CDFs and end-user functions (EFs). DSN CDF supports content distribution between CDFs NOTE 4 A DSN CDF can directly fetch data from other DSN CDFs. This helps to avoid additional transfers across Internet service provider (ISP) network links where possible. DSN CDF support content distr
47、ibution to EFs. NOTE 5 DSN CDF supports centralized content distribution and distributed content distribution. Centralized content distribution means content is directly distributed from one specific DSN CDF, to all EFs, which require the content, without distributing to other DSN CDF nodes. Distrib
48、uted content distribution means content is first distributed from one DSN CDF to other DSN CDFs located close to EFs, and is then distributed from these DSN CDFs to the requesting EFs. DSN CDF supports content delivery control. The delivery control can be per-application, per-peer or per-data. NOTE
49、6 An example for per-application control: one CDF node may run a video on demand (VoD) application and a live-streaming application simultaneously. The CDF node can control the delivery rate for different applications. NOTE 7 An example for per-peer control: application policy may indicate that certain peers have higher bandwidth. The CDF node should be able to satisfy such requirements. NOTE 8 An example for per-data control: application policy may
