1、 International Telecommunication Union ITU-T H.248.80TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (01/2014) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMSInfrastructure of audiovisual services Communication procedures Gateway control protocol: Usage of the revised SDP offer/answer model with ITU-T
2、H.248 Recommendation ITU-T H.248.80 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 C
3、ommunication 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
4、 and multimedia 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 colla
5、boration 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.5
6、69 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 AND APPLICATIONS FOR IPTV General a
7、spects 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.780H.789 E-HEALTH MULTIMEDIA SERVI
8、CES AND APPLICATIONS Interoperability compliance testing of personal health systems (HRN, PAN, LAN and WAN) H.820H.849 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.248.80 (01/2014) i Recommendation ITU-T H.
9、248.80 Gateway control protocol: Usage of the revised SDP offer/ answer model with ITU-T H.248 Summary Recommendation ITU-T H.248.80 describes the interworking of the session description protocol (SDP) described by the “Revised SDP Offer/Answer (O/A) model with ITU-T H.248“. This allows SDP capabili
10、ty negotiation and SDP media capabilities negotiation to be supported within ITU-T H.248. History Edition Recommendation Approval Study Group Unique ID*1.0 ITU-T H.248.80 2014-01-13 16 11.1002/1000/12060 _ *To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your
11、 web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T H.248.80 (01/2014) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and com
12、munication 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 questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
13、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 Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolutio
14、n 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 Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and
15、a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met
16、. 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 compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibi
17、lity 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 applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Rec
18、ommendation development process. As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information a
19、nd are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2014 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T H.248.80 (01/2014) iii Table of Contents P
20、age 1 Scope 1 2 References. 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acronyms 3 5 Conventions 4 6 Interworking the Revised Offer/Answer SDP “SDPCapNeg“ and ITU-T H.248.1 . 4 6.1 Revised Offer/Answer SDP received by MGC 4 6.2 Rev
21、ised Offer/Answer SDP initiated by MGC 8 7 Interworking the Revised Offer/Answer SDP “MediaCapNeg“ and ITU-T H.248.1 9 8 Enhanced Revised Offer/Answer SDP support in ITU-T H.248 10 9 Enhanced Revised Offer/Answer SDP Support Package . 10 9.1 Properties 10 9.2 Events . 10 9.3 Signals 10 9.4 Statistic
22、s 11 9.5 Error codes 11 9.6 Procedures 11 10 Enhanced SDP Media Capabilities Negotiation Support Package . 12 10.1 Properties 12 10.2 Events . 14 10.3 Signals 14 10.4 Statistics 14 10.5 Error codes 14 10.6 Procedures 14 11 Examples 15 11.1 Audit of SDPCapNeg extensions . 15 11.2 Example usage of SDP
23、 Capability Negotiation framework attributes . 15 11.3 Example usage of enhanced SDP Media Capabilities Negotiation Support 18 11.4 Further example with respect to session configurations . 20 11.5 Further example with respect to multiple latent configurations . 22 Bibliography. 26 iv Rec. ITU-T H.24
24、8.80 (01/2014) Rec. ITU-T H.248.80 (01/2014) 1 Recommendation ITU-T H.248.80 Gateway control protocol: Usage of the revised SDP offer/ answer model with ITU-T H.248 1 Scope Recommendation ITU-T H.248.80 describes the interworking of the SDP described by the “Revised SDP Offer/Answer (O/A) model“ wit
25、h ITU-T H.248. The “Revised SDP Offer/Answer model“ is characterized by the following documents: SDP capability negotiation (SDPCapNeg) defined in IETF RFC 5939 SDP media capabilities negotiation (MediaCapNeg) defined in IETF RFC 6871 NOTE The support of miscellaneous capabilities negotiation in the
26、 Session Description document b-IETF RFC 7006 and Extension for PSTN bearers b-IETF SDPCS is for further study. This Recommendation describes the relationship between the ITU-T H.248 group concept and the revised SDP offer/answer model concepts of actual and potential configurations. It provides gui
27、delines for the inter-working between SDPCapNeg and normal ITU-T H.248.1 procedures. Rather than focussing on the SDPCapNeg procedures in the context of session handling, this Recommendation concentrates on mapping the between ITU-T H.248.1 and the SDP Capability negotiation framework SDP syntax. Fo
28、r interactions between the functions of SDPCapNeg and different SDP attributes, see IETF RFC 5939 and associated IETF documents. This Recommendation also discusses the support of IETF RFC 6871 by ITU-T H.248. In order to address several deficiencies in interworking between SDPCapNeg and IETF RFC 687
29、1 and ITU-T H.248 this Recommendation defines two packages that allow a more optimized support of the revised SDP offer/answer procedures on MGCs that also support ITU-T H.248. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this t
30、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
31、 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-
32、T H.248.1 (2013), Gateway control protocol: Version 3. ITU-T H.248.39 Recommendation ITU-T H.248.39 (2006), Gateway control protocol: H.248 SDP parameter identification and wildcarding. ITU-T H.248.49 Recommendation ITU-T H.248.49 (2007), Gateway control protocol: Session description protocol RFC an
33、d capabilities packages. ITU-T H.248.63 Recommendation ITU-T H.248.63 (2009), Gateway control protocol: Resource management packages. ITU-T T.38 Recommendation ITU-T T.38 (2010), Procedures for real-time Group 3 facsimile communication over IP networks. IETF RFC 5939 IETF RFC 5939 (2010), Session De
34、scription Protocol (SDP) Capability Negotiation. 2 Rec. ITU-T H.248.80 (01/2014) IETF RFC 6871 IETF RFC 6871 (2013), Session Description Protocol (SDP) Media Capabilities Negotiation. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 actu
35、al configuration IETF RFC 6871: An actual configuration specifies which combinations of SDP session parameters and media stream components can be used in the current offer/answer exchange and with what parameters. Use of an actual configuration does not require any further negotiation in the offer/a
36、nswer exchange. See IETF RFC 5939 for further details. 3.1.2 potential configuration IETF RFC 6871: A potential configuration indicates which combinations of capabilities can be used for the session and its associated media stream components. Potential configurations are not ready for use, however t
37、hey are offered for potential use in the current offer/answer exchange. They provide an alternative that may be used instead of the actual configuration, subject to negotiation in the current offer/answer exchange. See IETF RFC 5939 for further details. 3.1.3 latent configuration IETF RFC 6871: A la
38、tent configuration indicates which combinations of capabilities could be used in a future negotiation for the session and its associated media stream components. Latent configurations are neither ready for use, nor are they offered for actual or potential use in the current offer/answer exchange. La
39、tent configurations merely inform the other side of possible configurations supported by the entity. Those latent configurations may be used to guide subsequent offer/answer exchanges, but they are not offered for use as part of the current offer/answer exchange. NOTE Latent configurations are benef
40、icial for fast transitioning between different media configurations during active communication phases. Examples: IP emulation services for PSTN teleservices like “alternate speech-facsimile“ or “text telephony“ calls. 3.2 Terms defined in this Recommendation This Recommendation defines the followin
41、g terms: 3.2.1 configuration: A configuration relates to a set of capabilities, which may be indicated and negotiated via a signalling protocol, or provisioned via a management protocol. NOTE This definition is derived from IETF RFC 5939, which itself does not provide an explicit definition of this
42、term. 3.2.1.1 media configuration: A media configuration typically covers capabilities such as media type, media format, all media format attributes, media transport stack, media transport capacity and all associated parameter values. NOTE 1 The notion of media originates from the concept of “IP med
43、ia-path“ (which relates to the ITU-T H.248 bearer-path), as opposed to the “IP signalling-path“. The IP packet flow of the IP media-path carries the application data between IP application endpoints and the IP signalling-path carries the correspondent application control information. NOTE 2 A media
44、configuration is specified within the SDP media description block. The relationship between the ITU-T H.248 “Media Descriptor“ and SDP “Media Description“ is illustrated in Figure 10 in ITU-T H.248.1. 3.2.1.2 session configuration: Defines a combination of multiple media configurations. NOTE This de
45、finition is derived from IETF RFC 6871, which itself does not provide an explicit definition of this term. Rec. ITU-T H.248.80 (01/2014) 3 3.2.2 configuration (codec) list: The term configuration list represents a list of media configurations within the SDP media description block (in the case of SI
46、P-embedded SDP). 3.2.3 SDP offer/answer protocol variants: The following names are applied in this Recommendation in order to distinguish different SDP Offer/Answer protocol variants. There are two models for the session description protocol (SDP) concerning the indication and negotiation of media a
47、nd transport capabilities: 3.2.3.1 legacy SDP Offer/Answer: This name indicates SDP Offer/Answer according to b-IETF RFC 3264. 3.2.3.2 revised SDP Offer/Answer: This name indicates SDP Offer/Answer according to IETF RFC 5939 and IETF RFC 6871. NOTE It is noted that the terms legacy and revised are n
48、ot related to the SDP syntax as such, rather to the overall “application“, i.e., the O/A negotiation protocol. It is not expected that the SDP syntax of b-IETF RFC 3264 will be made obsolete by the revised SDP Offer/Answer RFCs. It is expected that both SDP O/A protocol variants will be used in para
49、llel. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: DTMF Dual Tone Multi Frequency FoIP Fax over Internet Protocol FoUDPTL Fax over User Datagram Protocol Transport Layer IP Internet Protocol LD Local Descriptor MediaCapNeg Media Capabilities Negotiation MG Media Gateway MGC Media Gateway Controller MSRP Message Session Relay Protocol NTE Named Telephone Events O/A Offer/Answer PCMU Pulse C
