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.248.57 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (10/2014) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMS Infrastructure of audiovisual services Communication procedures Gateway control protocol: RTP control protocol
2、package Recommendation ITU-T H.248.57 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
3、 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 audiovis
4、ual 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 H.510H.
5、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 collaboration inter-
6、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 AND APPL
7、ICATIONS 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.780H.78
8、9 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.248.57 (10/2014
9、) i Recommendation ITU-T H.248.57 Gateway control protocol: RTP control protocol package Summary Recommendation ITU-T H.248.57 defines an ITU-T H.248 package for ephemeral terminations with real-time transport protocol-based streams and allows the media gateway controller to control the handling of
10、real-time transport protocol control protocol (RTCP) traffic within the ITU-T H.248 stream. RTCP handling comprises functions such as the indication of whether an RTCP flow is used, resource management functions for specific RTCP resources and the allocation scheme of transport port values. This rev
11、ision supports additional RTCP port allocation rules in the context of real-time transport protocol (RTP) transport multiplexing. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T H.248.57 2008-06-13 16 11.1002/1000/9483 2.0 ITU-T H.248.57 2013-03-16 16 11.1002/1000/11861 3.0
12、ITU-T H.248.57 2014-10-14 16 11.1002/1000/12239 _ * 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.248.57 (10/2014) FOREWORD
13、 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 responsible for studying tec
14、hnical, 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
15、, 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 collaborative basis with ISO and I
16、EC. 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 e
17、nsure, 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 d
18、oes not suggest that compliance 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 concerni
19、ng 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 property, protected by paten
20、ts, 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 2015 All rights reserved. No part of this public
21、ation may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T H.248.57 (10/2014) iii Table of Contents Page 1 Scope . 1 1.1 Overview 1 2 References . 2 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviatio
22、ns and acronyms 3 5 Conventions 3 6 RTCP Handling Package 3 6.1 Properties 3 6.2 Events . 4 6.3 Signals 4 6.4 Statistics 4 6.5 Error codes 4 6.6 Procedures 4 7 Additional support of RTP transport multiplexing . 8 7.1 Introduction 8 7.2 Backward compatibility 8 7.3 Summary of rules according to IETF
23、RFC 3550, IETF RFC 3605 and IETF RFC 5671 9 Annex A ITU-T H.248 profiles with and without support of RTCP Handling Package 16 A.1 Background . 16 A.2 ITU-T H.248 profiles without support of RTCP Handling Package 16 A.3 ITU-T H.248 profiles with support of RTCP Handling Package . 16 Bibliography. 17
24、Rec. ITU-T H.248.57 (10/2014) 1 Recommendation ITU-T H.248.57 Gateway control protocol: RTP control protocol package 1 Scope This Recommendation contains functionality to describe the use of the real-time transport protocol control protocol (RTCP) in ITU-T H.248-controlled media gateways. RTCP is us
25、ed, for example, to monitor the quality of service and to convey information about the participants in an on-going real-time transport protocol (RTP) session. ITU-T H.248.1 assumes that when an RTP stream is specified in a local or remote descriptor, that an RTCP flow may be established according to
26、 the rules defined in section 11 of IETF RFC 3550. Additional ITU-T H.248/RTCP behaviour is defined in clause E.12.5 of ITU-T H.248.1. However, some media gateways may not instantiate an RTCP flow. For interoperability and for some applications such as firewall and network address translation (NAT),
27、 it is important for the media gateway controller (MGC) to be certain of the media gateway (MG) behaviour with respect to port allocation for RTCP. The “RTCP Handling Package“ defined in this Recommendation provides a property to control this RTCP flow allocation. This revision supports additional R
28、TCP port allocation rules in context of RTP transport multiplexing. 1.1 Overview RTCP handling may comprise the following seven functions: 1) Indication of the existence of an RTCP flow of an RTP session (RTP with or without RTCP). 2) Indication of endpoint identifiers on RTP level that are relevant
29、 for both RTP and RTCP (e.g., synchronization source (SSRC). In addition, if an RTCP flow exists: 3) Resource management of endpoint identifiers on layer 4 (UDP ports; i.e., reservation, allocation and indication of a specific allocation rule) for RTCP flows. 4) Resource management of endpoint ident
30、ifiers on RTP level (e.g., CNAME) for RTCP flows. 5) Resource management of other resources required for RTCP flows (e.g., reservation and allocation of transport capacity). 6) Indication of specific modes of operation for RTCP (e.g., layer 4 multiplexing of RTP and RTCP flows, or multiplexing mode
31、of RTCP reports in a single RTCP packet). Orthogonal to the above functions: 7) Mapping scheme of RTP and RTCP flows on ITU-T H.248 streams. This Recommendation deals with functions one and three only. Other functions are out of the scope of this Recommendation. In addition, this Recommendation assu
32、mes that regarding function seven, RTP and RTCP flows are always mapped into a single ITU-T H.248 stream. Other mapping schemes are out of the scope of this Recommendation and may make this Recommendations procedures irrelevant. 2 Rec. ITU-T H.248.57 (10/2014) 2 References The following ITU-T Recomm
33、endations 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 the
34、refore 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 sta
35、nd-alone document, the status of a Recommendation. ITU-T H.248.1 Recommendation ITU-T H.248.1 (2013), Gateway control protocol: Version 3. IETF RFC 3550 IETF RFC 3550 (2003), RTP: A Transport Protocol for Real-Time Applications. IETF RFC 3605 IETF RFC 3605 (2003), Real Time Control Protocol (RTCP) a
36、ttribute in Session Description Protocol (SDP). IETF RFC 4566 IETF RFC 4566 (2006), SDP: Session Description Protocol. IETF RFC 5761 IETF RFC 5761 (04/2010), Multiplexing RTP Data and Control Packets on a Single Port. 3 Definitions 3.1 Terms defined elsewhere None. 3.2 Terms defined in this Recommen
37、dation This Recommendation defines the following terms: 3.2.1 RTCP flow: The sending and reception of RTCP packets as described by section 6 of IETF RFC 3550. The RTCP flow relates to an “(ITU-T H.248) control flow“ (see clause 3.2.9 of ITU-T H.248.1). NOTE An RTCP flow comprises all RTCP traffic on
38、 an RTP session. An RTCP flow may be further separated into RTCP sub-flows due to different RTCP report types. An RTCP sub-flow is identified by a specific RTCP packet type codepoint. 3.2.2 RTP flow: The sending and reception of RTP packets of an RTP session. The RTP flow relates to an “ITU-T H.248
39、media flow“ (see ITU-T H.248.1). 3.2.3 RTP/RTCP transport multiplexing: A single IP transport (L4) port for RTP and RTCP packets. NOTE This term may be also referred to as “RTP transport multiplexing“. 3.2.4 RTP session: An RTP session comprises a single RTP flow and an optional RTCP flow. Rec. ITU-
40、T H.248.57 (10/2014) 3 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: AVP Audio Visual Profile ISDN Integrated Services Digital Network LD Local Descriptor LS Local Source MG Media Gateway MGC Media Gateway Controller NAT Network Address Translation P
41、STN Public Switched Telephone Network RD Remote Descriptor RS Remote Source RTCP Real-time Transport protocol Control Protocol RTP Real-time Transport Protocol SDP Session Description Protocol SSRC Synchronization Source 5 Conventions None. 6 RTCP Handling Package Package name: RTCP Handling Package
42、 Package ID: rtcph (0x00b5) Description: This package allows the MGC to indicate to the MG per stream whether or not to establish an RTCP control flow when an RTP media flow (e.g., for RTP profiles such as RTP/AVP, etc.) is created. Version: 1 Extends: None. 6.1 Properties 6.1.1 RTCP Allocation Spec
43、ific Behaviour Property name: RTCP Allocation Specific Behaviour Property ID: rsb (0x0009) Description: This property indicates whether or not an RTCP flow and an associated port is automatically associated with an RTP flow. Type: Boolean Possible values: ON (an RTCP flow shall be allocated or de-al
44、located automatically with the creation or deletion of the RTP flow); 4 Rec. ITU-T H.248.57 (10/2014) OFF (an RTCP flow shall not be allocated or de-allocated automatically with the creation or deletion of the RTP flow) Default: Provisioned Defined in: Local control Characteristics: Read/Write 6.2 E
45、vents None. 6.3 Signals None. 6.4 Statistics None. 6.5 Error codes None. 6.6 Procedures 6.6.1 Reservation and allocation of layer 4 ports for RTP and RTCP The port number allocation rules, as defined by IETF RFC 3550, are used as the starting point. 6.6.1.1 Overview Four RTCP transport addresses Fig
46、ure 1 shows a bidirectional RTP session with RTCP in each direction: there are thus four traffic flows. The RTP-based media flow and RTCP-based control flow sharing the same IP addresses (see Note regarding possible exceptions), but using normally different layer 4 (L4) (UDP) ports. These four RTCP
47、ports are shown in Figure 1. NOTE The session description protocol (SDP) attribute “a=rtcp:“ also allows the explicit specification of an IP network address in addition to the layer 4 port. This may then lead to different IP addresses for RTP and RTCP flows. Figure 1 illustrates the particular case
48、of identical IP addresses. Rec. ITU-T H.248.57 (10/2014) 5 Figure 1 Connection endpoint naming conventions the four RTCP ports of a bidirectional RTP/RTCP session 6.6.1.2 Specific behaviour “activated“ If the MGC sets the rtcph/rsb property to “ON“, when the MG is requested to allocate/de-allocate a
49、 local destination port for an RTP stream, a consecutive port for the reception of the associated RTCP flow is automatically allocated/de-allocated. 6.6.1.3 Specific behaviour “deactivated“ If the MGC sets the rtcph/rsb property to “OFF“, then only a single port is allocated to the RTP stream and no RTCP flow is assumed to exist for the stream. 6.6.1.4 Precedence of rtcph/rsb property over other port allocation mechanisms The setting of the rtcph/rsb property in general takes p