1、 International Telecommunication Union ITU-T H.248.50TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (09/2010) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMSInfrastructure of audiovisual services Communication procedures Gateway control protocol: NAT traversal toolkit packages Recommendation ITU-T H.2
2、48.50 Copyright International Telecommunication Union/ITU Telcommunication Sector Provided by IHS under license with ITU-TNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-ITU-T H-SERIES RECOMMENDATIONS AUDIOVISUAL AND MULTIMEDIA SYSTEMS CHARACTERISTICS OF VISUAL TEL
3、EPHONE 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.259Coding of moving video H.260H.279 Related systems aspects H.280H.299 Systems and terminal equipme
4、nt 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 Supplementary services for multimedia H.450H.499 MOBILITY AND COLLABORATION PROCEDURES Overview
5、 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.520H.529 Security for mobile multimedia systems and services H.530H.539 Security for mobile mu
6、ltimedia collaboration applications and services H.540H.549 Mobility interworking procedures H.550H.559 Mobile multimedia collaboration inter-working procedures H.560H.569 BROADBAND, TRIPLE-PLAY AND ADVANCED MULTIMEDIA SERVICES Broadband multimedia services over VDSL H.610H.619 Advanced multimedia s
7、ervices 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 IPTV application event handling H.740H.749 IPTV metadata H.750H.759 IPTV multimedia application frameworks H.760H.769 IPTV ser
8、vice discovery up to consumption H.770H.779 For further details, please refer to the list of ITU-T Recommendations. Copyright International Telecommunication Union/ITU Telcommunication Sector Provided by IHS under license with ITU-TNot for ResaleNo reproduction or networking permitted without licens
9、e from IHS-,-,-Rec. ITU-T H.248.50 (09/2010) i 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 employ
10、ed in order to facilitate media flow between networks. Any of these packages may be utilized in any order to gather and map addresses, as well as maintain connectivity with and through NATs. History Edition Recommendation Approval Study Group 1.0 ITU-T H.248.50 2010-09-13 16 Copyright International
11、Telecommunication Union/ITU Telcommunication Sector Provided by IHS under license with ITU-TNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-ii Rec. ITU-T H.248.50 (09/2010) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized a
12、gency 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 tariff questions and issuing Recommendations on them with a vi
13、ew 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 Recommendations on these topics. The approval of ITU-T Recommenda
14、tions 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 Recommendation, the expression “Administration“ is used for concise
15、ness 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., interoperability or applicability) and compliance with the Recommendati
16、on 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 compliance with the Recommendation is required of any party. IN
17、TELLECTUAL 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, validity or applicability of claimed Intellectual Property Rights,
18、 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 required to implement this Recommendation. However, implementers a
19、re 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 2011 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permiss
20、ion of ITU. Copyright International Telecommunication Union/ITU Telcommunication Sector Provided by IHS under license with ITU-TNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Rec. ITU-T H.248.50 (09/2010) iii CONTENTS Page 1 Scope 1 2 References. 2 3 Definitions 3
21、 3.1 Terms defined elsewhere 3 3.2 Terms defined in this Recommendation . 3 4 Abbreviations and acronyms 3 5 Conventions 4 6 Toolkit usage 4 6.1 ITU-T H.248.50 usage in different network models 4 6.2 Overview of toolkit NAT traversal techniques 9 6.3 ITU-T H.248 call/bearer separation, connection mo
22、del and IP addresses for ephemeral terminations . 10 6.4 Specific SDP information elements 10 6.5 Overview of NAT traversal support mechanisms (by ITU-T H.248 entities) . 10 7 STUN and TURN support 11 7.1 STUN base package . 11 7.2 MG STUN client package 13 7.3 MG TURN client package 16 7.4 MGC STUN
23、 client package 19 7.5 STUN information package 20 8 ICE support . 23 8.1 MG act-as STUN server package . 24 8.2 Originate STUN continuity check package 25 9 Keep-alive and pinhole support 31 9.1 MGC-originated STUN request package . 31 9.2 Keep alive request package 33 Copyright International Telec
24、ommunication Union/ITU Telcommunication Sector Provided by IHS under license with ITU-TNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Copyright International Telecommunication Union/ITU Telcommunication Sector Provided by IHS under license with ITU-TNot for Resale
25、No reproduction or networking permitted without license from IHS-,-,-Rec. ITU-T H.248.50 (09/2010) 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 tech
26、niques to be employed in order 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
27、.248 MGC and media gateway (MG) to use the techniques defined by: Simple STUN reflexive address mapping as defined in IETF RFC 3489 and IETF RFC 5389. Reflected mapping address mapping using the TURN techniques as described in IETF RFC 5766. Comprehensive NAT traversal ICE techniques as described in
28、 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 performs STUN server discovery through the use of domain name system (DNS) look
29、up. Figure 1 summarizes the various packages as defined by this Recommendation. Every package is self-contained and does not use the extension principle. Copyright International Telecommunication Union/ITU Telcommunication Sector Provided by IHS under license with ITU-TNot for ResaleNo reproduction
30、or networking permitted without license from IHS-,-,-2 Rec. ITU-T H.248.50 (09/2010) H.248.50(10)_F01stuni/1 STUNinformationpackagemgstunc/1 MGSTUN clientpackagemgcstunc/1 (1) STUN and TURN supportSTUN:TURN:MGCSTUN clientpackage(3) Keep-alive and pinhole support(2) ICE supportstunb/1 STUNbasepackage
31、mgturnc/1 MGTURN clientpackagemgastuns/1 MG act-asSTUN serverpackageostuncc/1 mgcostunr/1 MGC originated STUN requestpackagekar/1 KeepaliverequestpackageFigure 1 Landscape of NAT traversal toolkit packages, categorized into three application areas 2 References The following ITU-T Recommendations and
32、 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 therefore encour
33、aged 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 stand-alone docu
34、ment, the status of a Recommendation. ITU-T H.248.1 Recommendation ITU-T H.248.1 (2005), Gateway control 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
35、protocol: IP NAPT traversal package. ITU-T Y.2111 Recommendation ITU-T Y.2111 (2008), Resource and admission control functions in next generation networks. IETF RFC 3489 IETF RFC 3489 (2003), STUN Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translators (NATs). IETF RFC 3
36、556 IETF RFC 3556 (2003), Session Description Protocol (SDP) Bandwidth Modifiers for RTP Control Protocol (RTCP) Bandwidth. Copyright International Telecommunication Union/ITU Telcommunication Sector Provided by IHS under license with ITU-TNot for ResaleNo reproduction or networking permitted withou
37、t license from IHS-,-,-Rec. ITU-T H.248.50 (09/2010) 3 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 5245 IETF RFC 5245 (2010), Interactive Connect
38、ivity 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 T
39、raversal Utilities for NAT (STUN). 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 NAT traversal ITU-T Y.2111: The operation of adapting the IP addresses so that the packets in the media flow can pass through a far-end (remote) NAT. 3.1
40、.2 network address translation ITU-T Y.2111: The operation by which IP addresses are translated (mapped) from one address domain to another address domain. 3.1.3 pinhole ITU-T H.248.37: A configuration of two associated H.248 IP terminations within the same context, which allows/prohibits unidirecti
41、onal forwarding of IP packets under specified conditions (e.g., address tuple). 3.1.4 symmetric NAT IETF RFC 3489: A symmetric NAT is one where all requests from the same internal IP address and port, to a specific destination IP address and port, are mapped to the same external IP address and port.
42、 3.2 Terms defined in this Recommendation None. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: ABNF Augmented Backus-Naur Form B2BIH Back-to-Back IP Host B2BUA Back-to-Back User Agent DCCP Datagram Congestion Control Protocol DNS Domain Name System FW
43、 FireWall ICE Interactive Connectivity Establishment IMS IP Multimedia Subsystem IP Internet Protocol ISDN Integrated Services Digital Network IUA ISDN User Adaptation MG Media Gateway Copyright International Telecommunication Union/ITU Telcommunication Sector Provided by IHS under license with ITU-
44、TNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4 Rec. ITU-T H.248.50 (09/2010) MGC Media Gateway Controller NAT Network Address Translation PES PSTN/ISDN Emulation Subsystem PSTN Public Switched Telephone Network RMG Residential Media Gateway RMGC Residential Med
45、ia Gateway Controller RTCP RTP Control Protocol RTP Real Time Protocol SCTP Stream Control Transmission Protocol SIP Session Initiation Protocol STUN Session Traversal Utilities for NAT TCP Transmission Control Protocol TLS Transport Layer Security TURN Traversal Using Relays around NAT UDP User Dat
46、agram Protocol UE User Equipment UNSAF UNilateral Self-Address Fixing 5 Conventions None. 6 Toolkit usage 6.1 ITU-T H.248.50 usage in different network models The ITU-T H.248 packages of this Recommendation may be applied in various network configurations. The clauses below illustrate some main scen
47、arios. 6.1.1 ITU-T H.248 MGC/MG as interim nodes in the end-to-end path between user equipment (with STUN client/server and/or ICE support) The NAT traversal support protocols STUN, TURN and ICE are IP application protocols. They are fundamentally deployed in IP hosts (behind NAT device(s) and IP ne
48、twork servers. The IP host function is located in the user equipment (UE) in Figure 2. The end-to-end IP bearer-path goes through an ITU-T H.248 media gateway (with an ITU-T H.248 IP-IP Context). There may be multiple NAT devices in the IP bearer-path (and IP signalling path(s). Figure 2 shows an example with four IP realms, separated by two standalone NAT devices. The third NAT function is provided by the ITU-T H.248 MG. NOTE The MG-internal NAT function is realized by the so-called back-to-back IP host (B2BIH) mode. Copyright
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