1、 International Telecommunication Union ITU-T F.746TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (06/2012) SERIES F: NON-TELEPHONE TELECOMMUNICATION SERVICES Audiovisual services Requirements of multimedia optimization control components Recommendation ITU-T F.746 ITU-T F-SERIES RECOMMENDATIONS NON
2、-TELEPHONE TELECOMMUNICATION SERVICES TELEGRAPH SERVICE Operating methods for the international public telegram service F.1F.19 The gentex network F.20F.29 Message switching F.30F.39 The international telemessage service F.40F.58 The international telex service F.59F.89 Statistics and publications o
3、n international telegraph services F.90F.99 Scheduled and leased communication services F.100F.104 Phototelegraph service F.105F.109 MOBILE SERVICE Mobile services and multidestination satellite services F.110F.159 TELEMATIC SERVICES Public facsimile service F.160F.199 Teletex service F.200F.299 Vid
4、eotex service F.300F.349 General provisions for telematic services F.350F.399 MESSAGE HANDLING SERVICES F.400F.499 DIRECTORY SERVICES F.500F.549 DOCUMENT COMMUNICATION Document communication F.550F.579 Programming communication interfaces F.580F.599 DATA TRANSMISSION SERVICES F.600F.699 AUDIOVISUAL
5、SERVICES F.700F.799ISDN SERVICES F.800F.849 UNIVERSAL PERSONAL TELECOMMUNICATION F.850F.899 HUMAN FACTORS F.900F.999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T F.746 (06/2012) i Recommendation ITU-T F.746 Requirements of multimedia optimization control compone
6、nts Summary Recommendation ITU-T F.746 defines multimedia optimization control components (MOCCs), which can provide guidance services to multimedia applications and services in the process of service node selection, traffic optimization, performance enhancement, etc. This Recommendation specifies t
7、he MOCC requirements and defines a MOCC functional model. Some typical MOCC deployment scenarios are also described. History Edition Recommendation Approval Study Group 1.0 ITU-T F.746 2012-06-29 16 Keywords Control component, multimedia applications, multimedia services, optimization. ii Rec. ITU-T
8、 F.746 (06/2012) FOREWORD 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 res
9、ponsible for studying 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
10、 ITU-T study groups which, 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 collabora
11、tive basis with ISO and 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 m
12、andatory provisions (to 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
13、. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU
14、takes no position concerning 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 pr
15、operty, protected by patents, 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 2013 All rights reserv
16、ed. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T F.746 (06/2012) 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 . 1 4 Abbrev
17、iations 2 5 Overview 2 6 Functional architecture . 2 7 Requirements 4 7.1 General requirements 4 7.2 MOCC service discovery requirements 4 7.3 Transport information collection requirements 5 7.4 Interaction and information exchange requirements 5 7.5 Security requirements . 5 Appendix I MOCC deploym
18、ent scenarios 6 I.1 MOCC deployment in distributed file share services systems . 6 I.2 MOCC deployment in the streaming services systems 10 I.3 MOCC deployment in NAT traversal and media relay 14 Rec. ITU-T F.746 (06/2012) 1 Recommendation ITU-T F.746 Requirements of multimedia optimization control
19、components 1 Scope The multimedia optimization control components (MOCCs) defined in this Recommendation are assistance entities which can obtain reliable information from the underlying network. This sort of information can be fed to multimedia applications and services and used as guidance service
20、s in the process of service node selection, data traffic optimization and performance enhancement. The MOCC component is located between the multimedia applications and services layer and the network layer. MOCC entities will not be involved in actual data relay and transmission. The MOCC components
21、 can be deployed either in distributed multimedia systems or traditional client-server systems. They can be used in various networks such as NGN ITU-T Y.2012, internet and other distributed systems. This Recommendation specifies requirements according to some typical scenarios. 2 References The foll
22、owing 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 references are subject to revision; users of this Reco
23、mmendation 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 reference to a document within this Recommendation does not
24、 give it, as a stand-alone document, the status of a Recommendation. ITU-T F.700 Recommendation ITU-T F.700 (2000), Framework Recommendation for multimedia services. ITU-T F.701 Recommendation ITU-T F.701 (2000), Guideline Recommendation for identifying multimedia service requirements. ITU-T Y.2012
25、Recommendation ITU-T Y.2012 (2010), Functional requirements and architecture of next generation networks. 3 Definitions 3.1 Terms defined elsewhere This Recommendation does not use any terms defined elsewhere. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms:
26、3.2.1 supernode: A peer in the overlay network that offers services, including message routing, to other members or clients of the overlay network. 3.2.2 tracker: An index server that can assist in the communication between peers in some peer-to-peer file sharing and multimedia systems by collecting
27、 information of file replicas and then providing the corresponding information to the resource demanders to initiate a download. 2 Rec. ITU-T F.746 (06/2012) 4 Abbreviations This Recommendation uses the following abbreviations and acronyms: AS Autonomous System CDN Content Delivery Network DOS Denia
28、l of Service ID Identity IP Internet Protocol IPv4 Internet Protocol version 4 IPv6 Internet Protocol version 6 ISP Internet Service Provider MOCC Multimedia Optimization Control Component NAT Network Address Translation NGN Next Generation Network NLRF Node Location Resolution Function P2P Peer to
29、Peer PoP Point of Presence RASF Resource Awareness and Statistics Function TCP Transmission Control Protocol VoIP Voice over Internet Protocol 5 Overview Due to the evolution of network and multimedia technologies, multimedia services are developing rapidly both on the system scale and on the volume
30、 of users, especially for services on the Internet. In contrast with traditional centralized service provision models, more and more services and applications tend to be deployed as distributed models, meaning that the data are transmitted along the paths established among nodes distributed across t
31、he whole network. Web content distribution, P2P streaming and P2P file sharing are typical examples of distributed models. For most distributed networks, each node should select one or more service providing nodes from a set of candidates to acquire the desired resources. However, under the end-to-e
32、nd principle, applications and underlying networks are separated except on the end nodes. Therefore, the “selection“ might be random, since the applications may not have the reliable information from transport networks such as topology, congestion status and network address translation (NAT) install
33、ation. Sometimes, nodes may cross several network boundaries to fetch the desired resources, thus generating a large amount of costly cross-ISP traffic. MOCCs defined in this Recommendation are complementary entities that can collect reliable information from the underlying network, analyse it and p
34、rovide guidance services to the multimedia applications and services (see ITU-T F.700 and ITU-T F.701) in the process of service node selection, data traffic optimization and performance enhancement. 6 Functional architecture Conceptually, multimedia optimization control components are located betwe
35、en the application and service layer and the network layer. The MOCC functional model is illustrated in Figure 1. It is composed of an MOCC server and MOCC clients. Rec. ITU-T F.746 (06/2012) 3 The MOCC server, which resides on the network side, is responsible for collecting and analysing the inform
36、ation from the underlying transport network, and for providing the processed information to multimedia services and applications and to the MOCC client. The MOCC server consists of an entrance component, a node location resolution function (NLRF) and a resource awareness and statistics function (RAS
37、F). F.746(12)_F01Multimedia services/applicationsIaIbMOCC entranceResource awareness andstatistics function(RASF)Node locationresolution function(NLRF)MOCC serverIdIcMOCC clientUnderlying transport networksOthernetworksEnd-userFigure 1 Functional architecture for multimedia optimization control comp
38、onents The functions of MOCC server components are as follows: MOCC entrance component: The MOCC entrance component provides registration and service discovery functions for NLRF, RASF and the MOCC client. NLRF and RASF should register its address, policies, server status and other information with
39、the MOCC entrance component. In order to select the optimum service providing nodes, since there might be multiple MOCC servers in the network, the client should be first authenticated to the MOCC entrance component, which will be responsible for providing the client with the address of the most pro
40、mising NLRF and RASF. The MOCC entrance component has interfaces with NLRF, RASF, as well as the MOCC clients. NLRF and RASF: NLRF and RASF can provide the guidance service or node selection service to applications by collecting and analysing the information of the underlying network. In practice, t
41、he NLRF and RASF can be implemented in one physical MOCC server. Network operators can deploy multiple MOCC servers with multiple instances of NLRF and RASF. The information of NLRF and RASF can be maintained by the MOCC entrance component. Some policies may be set for the clients to access NLRF and
42、 RASF. By collecting the information of the underlying network in real time, the MOCC servers could obtain reliable information, such as static topology of the whole network (maintained by NLRF) or dynamic network status (maintained by RASF). Network deployment information: This information is relat
43、ively stable, for example, link capacities, node locations and adjacency relationships of the service nodes, and NAT installations. Furthermore, basic information of the service nodes and some policies enforced by the carriers may also be included in network deployment information. This kind of info
44、rmation is collected and maintained by NLRF. Network resource status information: This information includes bandwidth-related data, congestion status of links, etc. This kind of information is more dynamic than network deployment information and can be used as a basis for load balancing and traffic
45、optimization. This kind of information is collected and maintained by RASF. 4 Rec. ITU-T F.746 (06/2012) The MOCC client is embedded in the end user device and is responsible for communicating with the MOCC server to acquire information (through interface Icin Figure 1) for multimedia service and ap
46、plication optimization. Multimedia optimization control components (MOCC server and MOCC client) have interfaces with the multimedia service and application control entities (Iain Figure 1), by which the multimedia system can acquire the necessary information from the transport network layer. In add
47、ition, those components should have interfaces with the transport network layer (Ibin Figure 1), through which they can collect and analyse the transport information according to the requirements of the given service. 7 Requirements 7.1 General requirements GEN-110: The MOCC can be installed on cent
48、ralized servers, or can be installed on multiple servers across the whole network. In any case, it should provide an interface to multimedia applications and services. The network information provided by the MOCC component should be accurate and reliable. GEN-120: Under the P2P application context,
49、according to the particular mechanism, the MOCC server should be able to be queried by the normal peers as well as by the P2P index servers. MOCCs should be suitable for different P2P systems and protocols, a general interface should be defined between MOCC and those applications. GEN-130: MOCCs should be able to process massive requests from the applications with reasonable and acceptable response time. Specific performance requirements shall be fulfilled. Those requirements may include, amongst others, response time, efficiency,
