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 H.248.92 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (10/2014) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMS Infrastructure of audiovisual services Communication procedures Gateway control protocol: Stream endpoint inter
2、linkage package Recommendation ITU-T H.248.92 ITU-T H-SERIES RECOMMENDATIONS AUDIOVISUAL AND MULTIMEDIA SYSTEMS CHARACTERISTICS OF VISUAL TELEPHONE SYSTEMS H.100H.199 INFRASTRUCTURE OF AUDIOVISUAL SERVICES General H.200H.219 Transmission multiplexing and synchronization H.220H.229 Systems aspects H.
3、230H.239 Communication procedures H.240H.259 Coding of moving video H.260H.279 Related systems aspects H.280H.299 Systems and terminal equipment for audiovisual services H.300H.349 Directory services architecture for audiovisual and multimedia services H.350H.359 Quality of service architecture for
4、audiovisual and multimedia services H.360H.369 Telepresence H.420H.429 Supplementary services for multimedia H.450H.499 MOBILITY AND COLLABORATION PROCEDURES Overview of Mobility and Collaboration, definitions, protocols and procedures H.500H.509 Mobility for H-Series multimedia systems and services
5、 H.510H.519 Mobile multimedia collaboration applications and services H.520H.529 Security for mobile multimedia systems and services H.530H.539 Security for mobile multimedia collaboration applications and services H.540H.549 Mobility interworking procedures H.550H.559 Mobile multimedia collaboratio
6、n inter-working procedures H.560H.569 BROADBAND, TRIPLE-PLAY AND ADVANCED MULTIMEDIA SERVICES Broadband multimedia services over VDSL H.610H.619 Advanced multimedia services and applications H.620H.629 Ubiquitous sensor network applications and Internet of Things H.640H.649 IPTV MULTIMEDIA SERVICES
7、AND APPLICATIONS FOR IPTV General aspects H.700H.719 IPTV terminal devices H.720H.729 IPTV middleware H.730H.739 IPTV application event handling H.740H.749 IPTV metadata H.750H.759 IPTV multimedia application frameworks H.760H.769 IPTV service discovery up to consumption H.770H.779 Digital Signage H
8、.780H.789 E-HEALTH MULTIMEDIA SERVICES AND APPLICATIONS Interoperability compliance testing of personal health systems (HRN, PAN, LAN and WAN) H.820H.859 Multimedia e-health data exchange services H.860H.869 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T H.248.92
9、(10/2014) i Recommendation ITU-T H.248.92 Gateway control protocol: Stream endpoint interlinkage package Summary The interlinkage of stream endpoints (SEP) relates to the empowerment of the MG by the MGC to perform the interconnection of two protocol endpoints. The interlinkage relates to abstracted
10、 bearer control protocol procedures as mainly part of the bearer establishment and release. The pair of protocol endpoints might be located in a single SEP or in different SEPs, leading to so-called intra-SEP and inter-SEP interlinkage configurations. Recommendation ITU-T H.248.92 defines an ITU-T H
11、.248 package that allows the MGC to signal such interlinkage configurations to the MG. The discussion of use cases, models and examples complements the description of the ITU-T H.248 protocol extensions. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T H.248.92 2014-10-14 16
12、11.1002/1000/12243 _ * 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 H.248.92 (10/2014) FOREWORD The International Telecommun
13、ication 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 technical, operating and tariff
14、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 which, in turn, produce Recommenda
15、tions 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 and IEC. NOTE In this Recommendati
16、on, 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 (to ensure, e.g., interoperability
17、 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 words does not suggest that complian
18、ce 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 concerning the evidence, validity or
19、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 patents, which may be required to
20、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 publication may be reproduced, by a
21、ny means whatsoever, without the prior written permission of ITU. Rec. ITU-T H.248.92 (10/2014) iii Table of Contents Page 1 Scope . 1 1.1 Applicability statements . 1 2 References . 2 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acro
22、nyms 3 5 Conventions 3 6 Motivation, use cases and models 3 7 Stream endpoint interlinkage package 7 7.1 Properties 7 7.2 Events . 8 7.3 Signals 8 7.4 Statistics 8 7.5 Error codes 8 7.6 Procedures 9 Appendix I Illustration of interlinkage capabilities 14 I.1 Illustration of concept . 14 I.2 Illustra
23、tion of supported use cases 14 I.3 Controversial use cases . 17 Appendix II Considerations about state modelling and dynamics 19 II.1 Purpose . 19 II.2 State modelling . 19 II.3 Interlinkage behaviour 20 II.4 Illustration of temporary interlinkage behaviour 22 Bibliography. 25 Rec. ITU-T H.248.92 (1
24、0/2014) 1 Recommendation ITU-T H.248.92 Gateway control protocol: Stream endpoint interlinkage package 1 Scope The ITU-T H.248 media gateway bearer interface protocol stack may contain principally connectionless and connection-oriented protocols. The concerned protocol layer(s) from ITU-T H.248 pers
25、pective, i.e., which are in scope of the ITU-T H.248 Stream Descriptors, are typically a network layer (L3) and higher. Connection-oriented protocols are known from L2 onwards in general, and in case of IP from L4 and higher concerning with respect to basic reference models for layered protocol arch
26、itectures. Connection-oriented protocols are characterized by explicit bearer connection control procedures, related to the establishment, modification and/or release of a bearer connection. Normally, the media gateway (MG) as slave is triggered by the master media gateway controller (MGC) for a par
27、ticular bearer connection control procedure, and then autonomously executing such a procedure at the bearer interface related to a particular ITU-T H.248 termination (T)/stream endpoint (SEP). The end-to-end bearer plane connectivity typically implies scenarios where multiple SEPs are interconnected
28、 in an ITU-T H.248 context. SEP-individual bearer control procedures are then often interlinked; e.g., an incoming bearer connection establishment procedure (at one SEP) could lead to an outgoing bearer connection establishment procedure (at a partner SEP), at the same or at a different protocol lay
29、er. An MGC may wish to individually control each of these procedures (so called MGC-strictly controlled mode). However, there are many use cases where the MGC could benefit from a delegation of “interlinkage work“ down to the MG itself. Such kind of behaviour is the purpose of this Recommendation. A
30、n ITU-T H.248 package, called the “stream endpoint interlinkage“ package (text codepoint seplink), is defined in a generic manner, which represents a flexible tool to enable a wide range of interlinkage options. The supported interlinkage is limited to a single context, is direction dependent, and a
31、llows the interlinkage of protocol endpoints, at the same or different layers, in different SEPs (“inter-SEP interlinkage“), and of protocol endpoints at different layers within an individual SEP (“intra-SEP interlinkage“), and allows multiple interlinkage configurations to be assigned to an individ
32、ual SEP. 1.1 Applicability statements The capability of “interlinkage“ relates to the MG internal forwarding of protocol control information (PCI) between different SEPs and/or different protocol layers. A layered protocol architecture is thus associated with a SEP. The interlinkage capability is li
33、mited to protocol stack segments, which may be unambiguously described via the mechanism in clause 7.1.1. 2 Rec. ITU-T H.248.92 (10/2014) The defined interlinkage capability is generic, i.e., applicable for all kind of connection-oriented bearer protocols. However, the focus of the initial package v
34、ersion is tightly coupled with protocols related to IP. 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 Rec
35、ommendations and other references 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 regular
36、ly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T H.248.1 Recommendation ITU-T H.248.1 (2013), Gateway control protocol: Version 3. ITU-T H.248.89 Recommendation ITU-T H.248.89 (2014), Gateway contr
37、ol protocol: TCP support packages. ITU-T X.200 Recommendation ITU-T X.200 (1994) | ISO/IEC 7498-1:1994, Information technology Open Systems Interconnection Basic Reference Model: The basic model. IETF RFC 4566 IETF RFC 4566 (2006), SDP: Session Description Protocol. 3 Definitions 3.1 Terms defined e
38、lsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 stream endpoint (SEP) ITU-T H.248.1: Relates to a stream associated to a Termination. A SEP is identified by the tuple of StreamID and TerminationID values. 3.1.2 stream endpoint pair (SEPP) ITU-T H.248.1: Two associated
39、stream endpoints (SEP) of two Terminations within the same Context. The two SEPs share thus the same StreamID value. There is always a point-to-point topology for stream endpoint pair configurations (e.g., there is no further associated SEP on a third Termination etc.). 3.2.3 stream endpoint tuple (
40、SEPT) b-ITU-T H-Sup.13: The generalization of a stream endpoint pair (SEPP) towards multiple associated stream endpoints (SEPs) within the same Context. All SEPs share thus the same StreamID value. The stream topology is given by the topology descriptor settings. 3.2 Terms defined in this Recommenda
41、tion This Recommendation defines the following term: 3.2.1 interlinkage: The media gateway controller (MGC) empowered interconnection of two protocol endpoints. The two protocol endpoints are associated to a single stream endpoint (SEP) or different SEPs within the same context. The media gateway (M
42、G) is enabled for autonomously forwarding of indicated stimuli from the source protocol endpoint to the destination endpoint. The stimuli relates to abstracted control information (and not any real layer x (Lx) protocol control information). Rec. ITU-T H.248.92 (10/2014) 3 4 Abbreviations and acrony
43、ms This Recommendation uses the following abbreviations and acronyms: ABNF Augmented Backus-Naur Format EP Endpoint IP Internet Protocol L2, L3, L4 (Protocol) Layer 2/3/4 Lx (Protocol) Layer x MG Media Gateway MGC Media Gateway Controller MSRP Message Session Relay Protocol PCI Protocol Control Info
44、rmation RTCP RTP Control Protocol RTP Real-time Transport Protocol S Stream SCTP Stream Control Transmission Protocol SDP Session Description Protocol SEP Stream Endpoint SEPP Stream Endpoint Pair SEPT Stream Endpoint Tuple T Termination TCP Transmission Control Protocol TLS Transport Layer Security
45、 UDP User Datagram Protocol UDPTL User Datagram Protocol Transport Layer 5 Conventions None. 6 Motivation, use cases and models ITU-T H.248 controlled media gateways (MGs) may terminate multiple connection-oriented transport layer protocols, like transmission control protocol (TCP), transport layer
46、security (TLS) and stream control transmission protocol (SCTP). This is outlined in Figure 1 where in a given ITU-T H.248 context each stream endpoint (SEP) hosts at least one or more connection-oriented transport layer endpoints. 4 Rec. ITU-T H.248.92 (10/2014) Figure 1 Two-termination context with
47、 multiple connection-oriented protocols in the SEP-specific protocol stack (segments) The interlinkage concept is constituted by the following characteristics: the interlinkage scope is limited to a single context; an interlinkage configuration is defined via an ITU-T H.248 Property, which itself is
48、 linked to a particular stream endpoint/termination; a specific external, incoming bearer control procedure (e.g., establishment event) immediately triggers the execution of an external, outgoing bearer control procedure, at the same or another termination in the context; a single interlinkage confi
49、guration acts in an unidirectional manner; and multiple interlinkage configurations in parallel may be defined for a single SEP. Thus, three principal interlinkage types may be differentiated (see also illustration in clause I.2): 1. inter-SEP interlinkage (when source and interlinked transport endpoints are located at different terminations); 2. intra-SEP interlinkage (when source and interlinked transport endpoints are located at the same termination); and 3. multi-SE
