1、 International Telecommunication Union ITU-T H.248.75TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (05/2011) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMSInfrastructure of audiovisual services Communication procedures Gateway control protocol: Package identifier publishing and application package R
2、ecommendation ITU-T H.248.75 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.230H.239 Communic
3、ation procedures H.240H.259Coding 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 audiovisual and mu
4、ltimedia services H.360H.369 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 H.510H.519 Mobile multimedia collaboratio
5、n 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 collaboration inter-working procedures H.560H.569 BROA
6、DBAND, TRIPLE-PLAY AND ADVANCED MULTIMEDIA SERVICES Broadband multimedia services over VDSL H.610H.619 Advanced multimedia services and applications H.620H.629 IPTV MULTIMEDIA SERVICES AND APPLICATIONS FOR IPTV General aspects H.700H.719 IPTV terminal devices H.720H.729 IPTV middleware H.730H.739 IP
7、TV 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 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T H.248.75 (05/2011) i Recommendation ITU-T H.248.7
8、5 Gateway control protocol: Package identifier publishing and application package Summary Recommendation ITU-T H.248.75 defines a new package that allows the media gateway controller (MGC) to determine the relationship between the base and extended packages as well as to determine or set which packa
9、ge ID (base or extended) will be used (published) in commands. It also allows the MGC to suppress the use of certain packages on the media gateway (MG). History Edition Recommendation Approval Study Group 1.0 ITU-T H.248.75 2011-05-14 16 ii Rec. ITU-T H.248.75 (05/2011) FOREWORD The International Te
10、lecommunication 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
11、 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 which, in turn, produce Re
12、commendations 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 Reco
13、mmendation, 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., interope
14、rability 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
15、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 takes no position concerning the evidence, val
16、idity 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 patents, which may be req
17、uired 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 2012 All rights reserved. No part of this publication may be reprodu
18、ced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T H.248.75 (05/2011) iii Table of Contents Page 1 Scope 1 2 References. 2 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviations any acronyms 2 5 Conventions 2 6 Pa
19、ckage identifier publishing issues . 3 6.1 Packages audit 3 6.2 Full and wildcarded package IDs . 3 7 Package identifier publishing and application package 4 7.1 Properties 4 7.2 Events . 6 7.3 Signals 6 7.4 Statistics 6 7.5 Error codes 6 7.6 Procedures 6 8 Package application examples 9 8.1 MGC to
20、MG direction 9 8.2 MG to MGC direction 9 Rec. ITU-T H.248.75 (05/2011) 1 Recommendation ITU-T H.248.75 Gateway control protocol: Package identifier publishing and application package 1 Scope One of the core functions provided by ITU-T H.248.1 is the ability to define “H.248 Packages“ which extend th
21、e capabilities of the protocol without modifying the protocol syntax. Properties, signals, events and statistics (known as ITU-T H.248 elements) may be defined via packages. An ITU-T H.248 package template allows the definition of properties, signals, events and statistics in a stand-alone manner in
22、dependent of other packages. Alternatively, it allows the package definition to inherit the properties, signals, events and statistics of another package and then add additional ITU-T H.248 elements or values to existing elements. ITU-T H.248s package extension mechanism allows for a nested inherita
23、nce, i.e., C can extend B which can extend A. However, in a package definition, the “extends“ relationship is only between two packages: a base package and an extended package. Thus, whether a package is deemed a base or an extended package is determined from this perspective. The terms “base packag
24、e“ and “extended package“ are defined in clause 3.2. For efficient communication between a media gateway controller (MGC) and a media gateway (MG), the two entities should agree on a common set of packages and how they will be used. Currently, this agreement is achieved by the MGC learning the list
25、of packages and package versions that the MG supports through an audit of the packages descriptor and/or the use of profiles. The MGC should then refrain from using any package that the MG does not support. This mechanism, while simple and robust, suffers from several limitations: The MGC cannot ask
26、 the MG to stop using certain package IDs. Where the MGC/MG utilize extension packages, whilst the MGC may only support the use of extended package IDs, the MG may, however, reply with a base package ID. This may cause parsing errors. Likewise the MGC may only support the use of base package IDs for
27、 the base elements and extended package IDs for the extended elements; however, the MG may reply using only the extended package ID for both elements. The MGC has no way to prevent this. The packages descriptor does not expose the relationship between base packages and extended packages supported by
28、 the MG. As explained under clause 6.2.3 of ITU-T H.248.1, some scenarios may cause an MG to encode package elements using a base package ID even when the MGC only implements the extended package, and vice versa. The MGC cannot ask the MG to stop using packages that the MGC does not support. The exi
29、stence of such packages will not prevent the MG from correctly processing requests sent by the MGC. However, elements belonging to these packages may appear in replies generated by the MG (for example, in replies to an AuditValue.req of a complete descriptor). These extra elements will unnecessarily
30、 increase the size of the replies, thus contributing to the signalling overhead. This Recommendation defines a new package that aims to resolve the above shortcomings. This package allows the MGC to determine the relationship between the base and extended packages as well as to determine/set which p
31、ackage ID (base and/or extended) will be used (published) in commands. It also allows the MGC to suppress the use of certain packages on the MG. 2 Rec. ITU-T H.248.75 (05/2011) 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this t
32、ext, 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 Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition
33、 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 give it, as a stand-alone document, the status of a Recommendation. ITU-T H.248.1 Recommendation ITU-
34、T H.248.1 (2005), Gateway control protocol: Version 3, up to and including Amendment 2 (12/2009). 3 Definitions 3.1 Terms defined elsewhere None. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 AuditCapabilities.req: ITU-T H.248.1 AuditCapabilities com
35、mand request. 3.2.2 AuditValue.req: ITU-T H.248.1 AuditValue command request. 3.2.3 base package (adapted from ITU-T H.248.1): A package that is supported by the media gateway (MG) and that is extended by at least one other package supported by the MG. 3.2.4 extended package (adapted from ITU-T H.24
36、8.1): A package that is supported by the MG and that extends at least one other package supported by the MG. NOTE An extended package may also be a base package. If package C extends package B and package B extends package A, then B is both an extended and a base package. 3.2.5 Notify.req: ITU-T H.2
37、48.1 Notify command request. 3.2.6 package element: A property, signal, event or statistic defined in a package. 3.2.7 PackageID: An ITU-T H.248 Package Identifier. See clause 12.1 of ITU-T H.248.1. 3.2.8 published package: A package that the MG includes in response to a packages descriptor audit. N
38、OTE Often the text will use phrases like “the package is published“ or “the MG publishes the package“ to indicate that the package is a published package. 3.2.9 stand-alone package: A package that is supported by the MG and that neither extends nor is extended by any other package supported by the M
39、G. 3.2.10 Subtract.req: ITU-T H.248.1 Subtract command request. 4 Abbreviations any acronyms This Recommendation uses the following abbreviations and acronyms: MG Media Gateway MGC Media Gateway Controller 5 Conventions None. Rec. ITU-T H.248.75 (05/2011) 3 6 Package identifier publishing issues Thi
40、s clause discusses different use cases concerning the use of base or extended package IDs. 6.1 Packages audit When an MG implements an extended ITU-T H.248 package and its base, ITU-T H.248.1 allows it to decide whether it will publish the base package ID in response to a packages audit from the MGC
41、. This behaviour is described in clause 6.2.3 of ITU-T H.248.1. If the MG decides to only publish the extended package ID, then only this package ID would be used to reference all ITU-T H.248 package elements (properties, signal, events and statistics) of the base and extended package in both ITU-T
42、H.248 command requests and replies. If the MG decides to publish both the base and extended package IDs, then the MGC and the MG can decide to use either the base or extended package IDs to reference the ITU-T H.248 package elements of the base package in command requests. How the MGC and MG decide
43、is discussed in clause 6.2 herein. By using the “Package Extension Information“ property from the “Package Identifier Publishing and Application Package“, the MGC is able to determine the relationship between an extended package and its base without the need for the provisioning of this information
44、in the MGC. 6.2 Full and wildcarded package IDs Where an MGC has fully specified the package ID in a command request, the MG uses this in the command reply, and vice versa. Where the MGC has wildcarded the package ID in a command request, by default the MG should reply with the package ID of the pac
45、kage where the ITU-T H.248 package element was originally defined, if the MG publishes both the related base package ID and extended package ID in response to a packages descriptor audit. Otherwise, the MG would use the extended package ID (in replacement of the base package ID for the base element)
46、 if it only publishes the extended package ID. For more information, see clause 6.2.3 of ITU-T H.248.1. There is no known case where an MG wildcards the package ID in a command request (e.g., Notify.req). The above behaviour of using both the base and extended package IDs may cause issues where an M
47、GC has only been provisioned with the knowledge of the extended package IDs (for base and extended elements) and does not accept an MG using a base package ID (that it has no prior knowledge of) in the response. Likewise, this may cause issues where an MGC has only been provisioned with the knowledg
48、e of the base package IDs for the base elements and extended package IDs for the extended elements. In this case, the MGC does not accept an MG using only the extended package IDs. The use of the “Base Package Publishing“ (pipa/bpp) property from the “Package Identifier Publishing and Application Pa
49、ckage“ allows the MGC to control how packages will be published and used as the interface between the MGC and MG in terms of the ITU-T H.248 control association. NOTE Whilst a Subtract.req does not explicitly request an AuditValue.req with a wildcarded package ID, it is implicit in the command. Thus it is in scope of the above wildcarded package ID usage. 4 Rec. ITU-T H.248.75 (05/2011) 7 Package identifier publishing and application package Package name: Package Identifier Publishing and Application PackageID: pipa
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