1、 International Telecommunication Union ITU-T Series HTELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Supplement 7(05/2008) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMSGateway control protocol: Establishment procedures for the H.248 MGC-MG control association ITU-T H-series Recommendations Supplement
2、 7 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 Communication procedures H.240H.25
3、9 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 audiovisual and multimedia services H.360H.
4、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 collaboration applications and servic
5、es 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.559Mobile multimedia collaboration inter-working procedures H.560H.569 BROADBAND, TRIPLE-PLAY AND ADV
6、ANCED MULTIMEDIA SERVICES Broadband multimedia services over VDSL H.610H.619 Advanced multimedia services 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 handl
7、ing H.740H.749 IPTV metadata H.750H.759 IPTV multimedia application frameworks H.760H.769 IPTV service discovery up to consumption H.770H.779 For further details, please refer to the list of ITU-T Recommendations. H series Supplement 7 (05/2008) iSupplement 7 to ITU-T H-series Recommendations Gatewa
8、y control protocol: Establishment procedures for the H.248 MGC-MG control association Summary This supplement to ITU-T H-series Recommendations provides clarifications on the operation of H.248 control associations with a focus on IP-based transport connections for H.248 signalling traffic and estab
9、lishment procedures, e.g., due to start-up phases or changeover scenarios of H.248 entities. Source Supplement 7 to ITU-T H-series Recommendations was agreed on 2 May 2008 by ITU-T Study Group 16 (2005-2008). H series Supplement 7 (05/2008) ii FOREWORD The International Telecommunication Union (ITU)
10、 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 technical, operating and tariff questions and issui
11、ng 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 turn, produce Recommendations on these topi
12、cs. 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. NOTE In this publication, the expression “Ad
13、ministration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this publication is voluntary. However, the publication may contain certain mandatory provisions (to ensure e.g., interoperability or applicability) and compli
14、ance with the publication 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 publication is requi
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17、enters 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 2009 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written
18、 permission of ITU. H series Supplement 7 (05/2008) iiiCONTENTS Page 1 Scope 1 2 References. 2 3 Definitions 4 4 Abbreviations and acronyms 4 5 Network conditions. 5 5.1 Introduction 5 5.2 Constitution of a control association 6 5.3 IP-based H.248 transport 7 5.4 Relation between the address of an H
19、.248 entity and an H.248 message identifier . 9 5.5 MG database for MGC entries . 9 5.6 Dedicated network applications . 11 6 Procedures for IP-based H.248 control associations 16 6.1 Starting point 16 6.2 Control association establishment 17 6.3 Control association refreshment. 21 7 Procedures for
20、non-IP-based H.248 control associations. 22 8 H.248 control association: summary of scenarios with usage of ServiceChangeMgcID parameter 23 8.1 Case a): Restart request (Initial registration) 23 8.2 Case b): Handoff request 24 8.3 Case c): Failover request 25 8.4 Case d): Disconnected H.248 control
21、association renewal request 27 8.5 Case e): Forced H.248 control association closure request 28 8.6 Case f): Graceful H.248 control association release request 29 9 H.248 control association: impact of protocol version changes and/or profile changes on established control associations. 30 10 H.248 c
22、ontrol association: Impact of transport mode changes. 31 10.1 Situation of transport mode changes 31 10.2 Impact on established control associations. 31 10.3 Relation between profile and transport modes . 32 10.4 Indication of transport mode 32 11 H.248 control association: registration of multi-mod
23、e transport capable media gateways . 32 11.1 Variant A: single-mode transport capable MGC 32 11.2 Variant B: multi-mode transport capable MGC, prepared to serve all transport modes 32 11.3 Variant C: multi-mode transport capable MGC, not prepared to serve all transport modes 32 H series Supplement 7
24、 (05/2008) iv Page 12 H.248 control association: policing of incoming H.248 messages. 33 12.1 Overview 33 12.2 Principal filter stages 34 12.3 MID Policing: filter rules, dependent on MID format and provisioned information . 37 H series Supplement 7 (05/2008) 1Supplement 7 to ITU-T H-series Recommen
25、dations Gateway control protocol: Establishment procedures for the H.248 MGC-MG control association 1 Scope This supplement provides clarifications on the operation of H.248 control associations (CA) and its scope includes: IP-based transport connections for H.248 signalling traffic, and Establishme
26、nt procedures, e.g., due to start-up phases or changeover scenarios of H.248 entities (see Figure 1 for a possible network configuration). Figure 1 Example for H.248 control associations (in a one-for-one redundancy model and an optional DNS Server) NOTE The concept of “primary“ and “secondary“ H.24
27、8 network elements is defined in clause 7.2.8 of ITU-T H.248.1. The number of secondary entities may vary from zero to more than one (see e.g., Table 2). Figure 1 depicts an example redundancy model with exactly one secondary entity at the media gateway controller (MGC) and at the media gateway (MG)
28、 levels. H series Supplement 7 (05/2008) 2 There is one H.248 control association between the primary network elements (indicated by the solid line). The dashed lines indicate potential future control associations in case of successful changeover procedures from primary to secondary H.248 network el
29、ements. Any H.248 network element itself may be designed for high availability. This is architecturally achieved on the basis of service or redundancy groups (“members of such a group are active and standby entities“). The corresponding entities may be abstracted by the working and protection planes
30、 internal to a network element, as indicated in Figure 1. Such network element-level architectural details are implementation-specific and beyond the scope of this supplement. A crucial point here is that, in Figure 1, such details of the internal operation of a network element are hidden from the n
31、etwork by a single H.248 control association endpoint of a H.248 network element. This abstract approach leads to a network design where the intra-network element changeover procedures are fully decoupled from the network-level or inter-network element changeover procedures. For instance, a MG inter
32、nal failover event does not have any impact on the externally visible H.248 control association. Any meaningful primary/secondary concept requires some kind of synchronization between the primary and secondary. Such kind of synchronization is outlined in Figure 1, but out of the scope of ITU-T H.248
33、.x-series of Recommendations. These mechanisms are mentioned for completeness because they are essential parts of network engineering. Changeover between primary and secondary network elements is discussed in clause 5.6.6. The potential involvement of DNS servers (as indicated in the figure) is in s
34、cope of clause 5.6.6.2.1. This supplement discusses typical use cases of H.248 control associations regarding: basic principles, address assignment mechanisms, traversal of multiple address realms, security, authentication of H.248 entities, changeovers between primary and secondary H.248 entities.
35、If there are any discrepancies between this supplement and ITU-T H.248.1, the procedures and specifications of ITU-T H.248.1 take precedence over those described in this supplement. 2 References ITU-T H.248.1 Recommendation ITU-T H.248.1 (2005), Gateway control protocol: Version 3. ITU-T H.248.4 Rec
36、ommendation ITU-T H.248.4 (2000), Gateway control protocol: Transport over Stream Control Transmission Protocol (SCTP). ITU-T H.248.5 Recommendation ITU-T H.248.5 (2000), Gateway control protocol: Transport over ATM. ITU-T H.248.41 Recommendation ITU-T H.248.41 (2006), Gateway control protocol: IP d
37、omain connection package. ITU-T Q.2631.1 Recommendation ITU-T Q.2631.1 (2003), IP connection control signalling protocol Capability Set 1. ITU-T Q-Sup.43 ITU-T Q-series Recommendations Supplement 43 (2003), Technical Report TRQ.2415: Transport control signalling requirements Signalling requirements
38、for IP connection control in radio access networks Capability Set 1. H series Supplement 7 (05/2008) 3ITU-T Y.2011 Recommendation ITU-T Y.2011 (2004), General principles and general reference model for Next Generation Networks. ITU-T Y.2012 Recommendation ITU-T Y.2012 (2006), Functional requirements
39、 and architecture of the NGN Release 1. ETSI ES 283 002 ETSI ES 283 002 V2.1.0 (2008-03) Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); H.248 Profile for controlling Access and Residential Gateways. ETSI ES 283 018 ETSI ES 283 018 v2.3.1 (2008-06),
40、 Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN); Resource and Admission Control: H.248 Profile for controlling Border Gateway Functions (BGF) in the Resource and Admission Control Subsystem (RACS); Protocol specification. ETSI TS 129 202 ETSI TS 129
41、 202 v6.0.0 (2004-12), Universal Mobile Telecommunications System (UMTS); Signalling System No. 7 (SS7) signalling transport in core network; Stage 3 (3GPP TS 29.202 version 6.0.0 Release 6). ETSI TS 133 210 ETSI TS 133 210 v7.3.0 (2007-10), Digital cellular telecommunications system (Phase 2+); Uni
42、versal Mobile Telecommunications System (UMTS); 3G security; Network Domain Security (NDS); IP network layer security (3GPP TS 33.210 version 7.3.0 Release 7). IETF RFC 793 IETF RFC 793 (1981), Transmission Control Protocol. http:/www.ietf.org/rfc/rfc0793.txt?number=793 IETF RFC 2131 IETF RFC 2131 (
43、1997), Dynamic Host Configuration Protocol. IETF RFC 2663 IETF RFC 2663 (1999), IP Network Address Translator (NAT) Terminology and Considerations. IETF RFC 3054 IETF RFC 3054 (2001), Megaco IP Phone Media Gateway Application Profile. IETF RFC 3489 IETF RFC 3489 (2003), STUN Simple Traversal of User
44、 Datagram Protocol (UDP) Through Network Address Translators (NATs). IETF RFC 3704 IETF RFC 3704 (2004), Ingress Filtering for Multihomed Networks. IETF RFC 3989 IETF RFC 3989 (2005), Middlebox Communications (MIDCOM) Protocol Semantics. IETF RFC 4301 IETF RFC 4301 (2005), Security Architecture for
45、the Internet Protocol. IETF RFC 4302 IETF RFC 4302 (2005), IP Authentication Header. H series Supplement 7 (05/2008) 4 IETF RFC 4303 IETF RFC 4303 (2005), IP Encapsulating Security Payload (ESP). IETF RFC 4960 IETF RFC 4960 (2007), Stream Control Transmission Protocol. 3 Definitions This supplement
46、defines the following terms: 3.1 5-tuple: The commonly used tuple of IP protocol control information fields. A 5-tuple is a subset of an address tuple. 3.2 address tuple: As defined in clause 2.3.5 of IETF RFC 3989. 3.3 destination-2-tuple: The commonly used tuple of IP protocol control information
47、fields. A destination 2-tuple is a subset of 5-tuple. 3.4 IP connection: A bidirectional (user plane) association between two IP (signalling) endpoints (aligned with clause 3.1 of ITU-T Q-Sup.43). An IP connection is designated by a pair of IP address/port number combinations (according to clause 3.
48、1 of ITU-T Q.2631.1). An IP connection is therefore related to the 4-tuple . 3.5 (IP) interface redirection: Relates to a change of the destination-2-tuple fields IP DA or IP DA and IP DP (during the control association establishment phase). 3.6 (IP) port redirection: Relates to a change of the dest
49、ination-2-tuple field IP DP (during the control association establishment phase). 3.7 receiver-2-tuple: The commonly used tuple of IP protocol control information fields at an IP interface for received IP packets. In a H.248 control association, a receiver-2-tuple relates therefore to the destination-2-tuple for the peer H.248 entity. 3.8 source-2-tuple: The commonly used tuple of IP protocol control information fields. A source 2-tuple is a subset of 5-tuple.
