1、 International Telecommunication Union ITU-T H.248.45TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (05/2006) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMSInfrastructure of audiovisual services Communication procedures Gateway control protocol: MGC information package ITU-T Recommendation H.248.45 I
2、TU-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 Communication procedures H.240H.259 Co
3、ding 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 multimedia services H.360H.369
4、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 collaboration applications and services H
5、.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.559Mobile multimedia collaboration inter-working procedures H.560H.569 BROADBAND AND TRIPLE-PLAY MULTIMED
6、IA SERVICES Broadband multimedia services over VDSL H.610H.619 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. H.248.45 (05/2006) i ITU-T Recommendation H.248.45 Gateway control protocol: MGC information package Summary This Recommendation describes an extension to
7、 the ITU-T Rec. H.248.1 Gateway Control Protocol to enable an MGC to store data on an MG that can be subsequently retrieved to facilitate MGC recovery action. Source ITU-T Recommendation H.248.45 was approved on 29 May 2006 by ITU-T Study Group 16 (2005-2008) under the ITU-T Recommendation A.8 proce
8、dure. ii ITU-T Rec. H.248.45 (05/2006) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technic
9、al, 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 which, in
10、 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 and IEC.
11、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 (to ensur
12、e 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 words does no
13、t 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 takes no position concerning th
14、e 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 patents, w
15、hich may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2006 All rights reserved. No part of this publication may be reproduced, by any means
16、 whatsoever, without the prior written permission of ITU. ITU-T Rec. H.248.45 (05/2006) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Terms and Definitions 1 4 Abbreviations 1 5 MGC Information Package. 2 5.1 Properties 2 5.2 Events . 2 5.3 Signals 2 5.4 Statistics 2 5.5 Error Codes. 2 5.6 Procedure
17、s 3 ITU-T Rec. H.248.45 (05/2006) 1 ITU-T Recommendation H.248.45 Gateway control protocol: MGC information package 1 Scope This Recommendation describes an extension to ITU-T Rec. H.248.1 1 gateway control protocol to enable an MGC to store data on an MG that can be subsequently retrieved to facili
18、tate MGC recovery action. The standard H.248 audit mechanism permits an MGC to retrieve data from an associated MG in order to re-synchronize connection data/state between an MGC and an MG. In terms of identifying the other end of this bearer connection, the Remote Descriptor that is associated with
19、 the ephemeral termination enables the other end of the bearer connection to be identified albeit not in a format that may be convenient for the MGC to use. In many cases, the Remote Descriptor may not enable the other end to be identified (e.g., some MGs may use different control and media addresse
20、s). In order to achieve a coordinated recovery action, whereby both GW connections in a single call/end-to-end connection can be torn down in parallel, it is proposed to define this H.248 package to enable the MGC to store a block of data on an MG which enables the MGC to identify the other end of t
21、he bearer connection. The structure of the stored data is understood only by the MGC and is opaque to the MG. Thus, the MGC is now able, via standard H.248 audit mechanisms, to retrieve the previously stored data block in the event of an MGC failure. The MGC is now able to identify the other end of
22、the connection (e.g., typically on separate MGs) and thus provide a coordinated clean-up of the related connections on the separate MGs. The MGC is at liberty to define the contents of the string in a proprietary manner that is most convenient for its own usage. 2 References The following ITU-T Reco
23、mmendations 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 Recommendation are t
24、herefore 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 give it, as a s
25、tand-alone document, the status of a Recommendation. 1 ITU-T Recommendation H.248.1 (09/2005), Gateway control protocol: Version 3. 3 Terms and definitions See ITU-T Rec. H.248.1. This Recommendation uses no particular terms and definitions. 4 Abbreviations This Recommendation uses the following abb
26、reviations: AGW Access GateWay CIC Call Identification Code GW GateWay ISUP ISDN User Part MG Media Gateway MGC Media Gateway Controller 2 ITU-T Rec. H.248.45 (05/2006) REL RELease message SDP Session Description Protocol SS7 Signalling System No. 7 TGW Trunking GateWay 5 MGC Information Package Pac
27、kage Name: MGC Information package PackageID: MGCInfo (0x00a0) Description: This package enables the MGC to store an opaque data block against a physical or ephemeral termination in the MG. The data block is applicable when the termination is involved in a connection and is thus defined in the Local
28、Control Descriptor. Version: 1 Extends: None 5.1 Properties 5.1.1 Data Block Property Name: Data Block PropertyID: db (0x0001) Description: This property holds the MGC (Recovery) Information data block. Type: Octet String Possible values: A range of zero to 128 octets. The range can be further limit
29、ed in the appropriate H.248 Profile, which defines the application, which utilizes this property. Default: An empty string Defined in: LocalControl Characteristics: read/write 5.2 Events None. 5.3 Signals None. 5.4 Statistics None. 5.5 Error Codes No additional error codes. ITU-T Rec. H.248.45 (05/2
30、006) 3 5.6 Procedures 5.6.1 Setting the property The property is set by the MGC when a termination (either physical or ephemeral) is placed into a non-NULL Context. Having been initially set, it is permissible for the MGC to subsequently modify the property by overwriting the previous setting. 5.6.2
31、 Resetting the property The property is reset to its default value when a physical termination is returned into the NULL Context. For ephemeral terminations, the property shall be set to the default value when the ephemeral termination is created and no string has been supplied by the MGC. 5.6.3 Ret
32、rieving the property The property is retrieved by the MGC in the event of an MGC failure. The retrieval is performed via the H.248 audit mechanism. The property is part of the LocalControl Descriptor and is thus retrieved using the AuditValue command that specifies a specific TerminationID. The audi
33、t may be performed against either the Media Descriptor (which contains the LocalControl Descriptor) or else the individual property within the LocalControl Descriptor, i.e., AuditMedia or AuditMedia Stream=1LocalControlMGCInfo/db 5.6.4 Example scenario Consider a stable call/bearer connection betwee
34、n a TGW and an AGW both MGs being under the control of a single MGC (see Figure 1). During the supervision phase, the MGC suffers a failure/disturbance and loses its transient memory. Figure 1/H.248.45 Example of scenario where two MGs are controlled by a single MGC 4 ITU-T Rec. H.248.45 (05/2006) A
35、s part of its normal recovery action, the MGC would typically perform H.248 audits on its MGs to re-synchronize its lost data. This is typically done as a background activity. In addition, call control signalling messages will also be received which will also initiate H.248 audit activity. Consider
36、that an SS7 “ISUP-REL“ message is received for the active call. The MGC will now: 1) Translate the SS7 CIC identity to corresponding TGW and endpoint identity (H.248 TerminationID). 2) The H.248 audit mechanism enables the MGC to determine that the endpoint is connected (in a non-NULL Context) and a
37、lso the related ephemeral endpoint identity (H.248 TerminationID). 3) In terms of identifying the other end of this connection, the MGC also retrieves the MGC information string (that was previously stored when the connection was established). The string may be stored/retrieved via either a physical
38、 or ephemeral termination. 4) The MGC is now able to interpret the previously stored string as identifying the associated AGW termination. As a result, the call may be torn down in a coordinated manner dealing with both MGs concerned. The MGC information string thus permits a faster and better coord
39、inated recovery by the MGC. This approach can be extended to any number of terminations within a context e.g., each termination within a 3-way connection/context may each be provided with a separate MGC Information data block. Printed in Switzerland Geneva, 2006 SERIES OF ITU-T RECOMMENDATIONS Serie
40、s A Organization of the work of ITU-T Series D General tariff principles Series E Overall network operation, telephone service, service operation and human factors Series F Non-telephone telecommunication services Series G Transmission systems and media, digital systems and networks Series H Audiovi
41、sual and multimedia systems Series I Integrated services digital network Series J Cable networks and transmission of television, sound programme and other multimedia signals Series K Protection against interference Series L Construction, installation and protection of cables and other elements of ou
42、tside plant Series M Telecommunication management, including TMN and network maintenance Series N Maintenance: international sound programme and television transmission circuits Series O Specifications of measuring equipment Series P Telephone transmission quality, telephone installations, local lin
43、e networks Series Q Switching and signalling Series R Telegraph transmission Series S Telegraph services terminal equipment Series T Terminals for telematic services Series U Telegraph switching Series V Data communication over the telephone network Series X Data networks, open system communications and security Series Y Global information infrastructure, Internet protocol aspects and next-generation networks Series Z Languages and general software aspects for telecommunication systems
