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.248.50 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (07/2016) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMS Infrastructure of audiovisual services Communication procedures Gateway control protocol: NAT traversal toolkit
2、 packages Recommendation ITU-T H.248.50 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.2
3、39 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 audiov
4、isual 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.510
5、H.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 inte
6、r-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 AP
7、PLICATIONS 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.
8、789 E-HEALTH MULTIMEDIA SERVICES AND APPLICATIONS Personal health systems H.810H.819 Interoperability compliance testing of personal health systems (HRN, PAN, LAN, TAN 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 Rec
9、ommendations. Rec. ITU-T H.248.50 (07/2016) i Revised Recommendation ITU-T H.248.50 Gateway control protocol: NAT traversal toolkit packages Summary Recommendation ITU-T H.248.50 contains a series of ITU-T H.248 packages that enable various network address translator (NAT) traversal techniques to be
10、 employed in order to facilitate media flow between networks or user equipment and network-side located media gateways. Any of these packages may be utilized in any order to gather and map addresses, as well as maintain connectivity with and through NATs. This revision of Recommendation ITU-T H.248.
11、50 adds clarifications and further capabilities, such as: a new ITU-T H.248 session traversal utilities for NAT (STUN) consent freshness package; package-independent ITU-T H.248 procedures for specific NAT traversal use cases; interactive connectivity establishment (ICE) variants (full vs ICE lite;
12、user equipment (UE)-embedded vs gateway-embedded ICE clients; vanilla vs trickle ICE; ICE for user datagram protocol (UDP) vs ICE for TCP; ICE for single-homed vs multi-homed host entities); and updates to keep alive support. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T H
13、.248.50 2010-09-13 16 11.1002/1000/10984 1.1 ITU-T H.248.50 (2010) Cor. 1 2012-02-13 16 11.1002/1000/11542 2.0 ITU-T H.248.50 2016-07-14 16 11.1002/1000/12919 Keywords FW, Gateway, ITU-T H.248, ICE, NAT, STUN, TURN. * To access the Recommendation, type the URL http:/handle.itu.int/ in the address fi
14、eld 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.248.50 (07/2016) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, informat
15、ion 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 questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldw
16、ide 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 Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTS
17、A 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 Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administ
18、ration and 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 provisi
19、ons 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 compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTSITU draws attention to t
20、he 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 applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside
21、of the Recommendation 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 inf
22、ormation and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2016 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.248.50 (07/2016) iii Table of
23、Contents Page 1 Scope . 1 1.1 Relation to other ITU-T H.248 related NAT traversal mechanisms 2 2 References . 3 3 Definitions 4 3.1 Terms defined elsewhere 4 3.2 Terms defined in this Recommendation . 4 4 Abbreviations and acronyms 5 5 Conventions 6 6 Toolkit usage 6 6.1 ITU-T H.248.50 usage in diff
24、erent network models 6 6.2 Overview of toolkit NAT traversal techniques 13 6.3 ITU-T H.248 call/bearer separation, connection model and IP addresses for ephemeral terminations . 13 6.4 Specific SDP information elements 14 6.5 Overview of NAT traversal support mechanisms (by ITU-T H.248 entities) . 1
25、5 7 STUN and TURN support 16 7.1 STUN base package . 16 7.2 MG STUN client package 18 7.3 MG TURN client package 21 7.4 MGC STUN client package 25 7.5 STUN information package 27 8 ICE support . 29 8.1 MG act-as STUN server package . 31 8.2 Originate STUN continuity check package 33 8.3 STUN consent
26、 freshness package 39 9 Keep-alive and pinhole support 43 9.1 MGC-originated STUN request package . 43 9.2 Keep alive request package 45 10 Package-independent NAT-T procedures . 47 10.1 Support for MG terminated STUN-based connectivity checks 47 Appendix I Example signalling scenarios for package-i
27、ndependent NAT-T procedures . 50 I.1 Example #1: ICE/STUN support by ITU-T H.248 IP access gateways . 50 Appendix II ICE for TCP 53 II.1 Introduction 53 II.2 MG bearer interface: protocol stack . 53 II.2 Bearer establishment 53 II.3 TCP address candidates 53 iv Rec. ITU-T H.248.50 (07/2016) Page App
28、endix III ICE mode support by gateway-embedded ICE agents 55 III.1 Background . 55 III.2 Main differences between ICE-full and ICE-lite 55 Appendix IV ICE extensions: “Trickle ICE“ 58 IV.1 Introduction 58 IV.2 Impact of trickle ICE on ITU-T H.248.50-defined packages . 59 IV.3 Example signalling flow
29、s for trickle ICE . 59 IV.4 Summary . 59 Appendix V ICE multihomed and IPv4/IPv6 dual stack fairness . 60 V.1 Introduction 60 V.2 Impact on ITU-T H.248 gateways with ICE support? . 60 Appendix VI ICE restarts 61 VI.1 Introduction 61 VI.2 ICE restart procedures 61 VI.2 Impact on ITU-T H.248 gateways
30、with ICE support? . 61 Bibliography. 62 Rec. ITU-T H.248.50 (07/2016) 1 Recommendation ITU-T H.248.50 Gateway control protocol: NAT traversal toolkit packages 1 Scope This Recommendation describes packages to enable various network address translator (NAT) traversal techniques to be employed in orde
31、r to facilitate media flow between networks. The media gateway controller (MGC) may utilize any of the packages in any order to gather addresses, map them and then maintain connectivity with and through NATs. The packages described in this Recommendation allow an ITU-T H.248 MGC and media gateway (M
32、G) to use the techniques defined by: simple session traversal utilities for NAT (STUN) reflexive address mapping as defined in IETF RFC 3489 and IETF RFC 5389; relayed address mapping using the traversal using relays around NAT (TURN) techniques as described in IETF RFC 5766; comprehensive NAT trave
33、rsal interactive connectivity establishment (ICE) techniques as described in IETF RFC 5389. In order to maintain backward compatibility, packages have been produced for both STUN as defined by IETF RFC 3489 and by IETF RFC 5389. Throughout this Recommendation it is assumed that the media gateway per
34、forms STUN server discovery through the use of domain name system (DNS) lookup. Figure 1 summarizes the various packages as defined by the initial Recommendation. Every package is self-contained and does not use the extension principle. 2 Rec. ITU-T H.248.50 (07/2016) H. 2 4 8 . 5 0 ( 1 0 ) _ F 0 1s
35、 t un i / 1 ST U Ni nf o r m at i o npa cka gem gs t un c / 1 MGST U N cl i e ntpa cka gem gcs t un c/ 1 ( 1) ST U N and T U R N s upp o r tST U N :T U R N :M G CST U N cl i e ntpa cka ge( 3) K ee p- a l i ve an d p i n hol e s upp or t( 2) I C E s u ppo r ts t un b/ 1 ST U Nba s epa cka gem gt urnc
36、/ 1 MGT U R N cl i en tpa cka gem gas t un s / 1 M G a ct - asST U N s er ve rpa cka geos t un c c/ 1 m gco s t un r/ 1 M G C or i gi n at ed ST U N r e ques tpa cka geka r / 1 K ee pal i v er eque s tpa cka geFigure 1 Landscape of NAT traversal toolkit packages, categorized into three application a
37、reas (status of ITU-T H.248.50 (09/2010) ITU-T H.248.50 (07/2016) adds clarifications and further capabilities, such as: a new ITU-T H.248 STUN consent freshness package; package-independent ITU-T H.248 procedures for specific NAT traversal use cases; ICE variants (full vs ICE lite; user equipment (
38、UE)-embedded vs gateway-embedded ICE clients; vanilla vs trickle ICE; ICE for user datagram protocol (UDP) vs ICE for TCP; ICE for single-homed vs multi-homed host entities); updates to keep alive support; and clarifies support of “ICE restart“ procedures. 1.1 Relation to other ITU-T H.248 related N
39、AT traversal mechanisms The following covers the applicability of this Recommendation versus other ITU-T H.248 supported NAT-T mechanisms: Transport protocol generic NAT-T method “media latching“ ITU-T H.248.37: this is an orthogonal mechanism and may be used in combination with this Recommendation;
40、 some of the mechanisms in this Recommendation make “media latching“ unnecessary. NOTE There is also a bearer plane latching process in the context of ICE, see clause 10.1.5 “STUN-specific media latching“. The difference between both latching variants is illustrated in Appendix I. It is further note
41、d that the IETF “media latching“ function of b-IETF RFC 7362 is synonymous to “H.248.37 latching“ (because it makes the assumption that ICE/STUN/TURN is not applied for NAT traversal). Rec. ITU-T H.248.50 (07/2016) 3 Transport protocol specific NAT-T method “TCP merge mode“ b-ITU-T H.248.84: this re
42、presents a TCP simultaneous open from an end-to-end perspective, which is, if applicable, used before any “ICE for TCP“ procedures are selected. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of th
43、is 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 of the Recommendations and othe
44、r 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-T H.248.1 (2005), Gateway contro
45、l protocol: Version 3. ITU-T H.248.14 Recommendation ITU-T H.248.14 (2009), Gateway control protocol: Inactivity timer package. ITU-T H.248.37 Recommendation ITU-T H.248.37 (2008), Gateway control protocol: IP NAPT traversal package. ITU-T H.248.40 Recommendation ITU-T H.248.40 (2013), Gateway contr
46、ol protocol: Application data inactivity detection package. ITU-T H.248.90 Recommendation ITU-T H.248.90 (2014), Gateway control protocol: ITU-T H.248 packages for control of transport security using transport layer security (TLS). ITU-T H.248.97 Recommendation ITU-T H.248.97 (2016), Gateway Control
47、 Protocol: ITU-T H.248 support for control of SCTP bearer connections.IETF RFC 3489 IETF RFC 3489 (2003), STUN Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translators (NATs). IETF RFC 3556 IETF RFC 3556 (2003), Session Description Protocol (SDP) Bandwidth Modifiers for R
48、TP Control Protocol (RTCP) Bandwidth. IETF RFC 3605 IETF RFC 3605 (2003), Real Time Control Protocol (RTCP) attribute in Session Description Protocol (SDP). IETF RFC 4566 IETF RFC 4566 (2006), SDP: Session Description Protocol. IETF RFC 4787 IETF RFC 4787 (2007), Network Address Translation (NAT) Be
49、havioral Requirements for Unicast UDP. IETF RFC 5245 IETF RFC 5245 (2010), Interactive Connectivity Establishment (ICE): A Protocol for Network Address Translator (NAT) Traversal for Offer/Answer Protocols. IETF RFC 5389 IETF RFC 5389 (2008), Session Traversal Utilities for NAT (STUN). IETF RFC 5766 IETF RFC 5766 (2010), Traversal Using Relays around NAT (TURN): Relay Extensions to Session Traversal Utilities for NAT (STUN). IE
