1、 International Telecommunication Union ITU-T H.361TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (05/2006) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMSInfrastructure of audiovisual services Quality of service architecture for audiovisual and multimedia services End-to-end quality of service (QoS) a
2、nd service priority signalling in H.323 systems ITU-T Recommendation H.361 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
3、H.220H.229 Systems aspects H.230H.239 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
4、 of service architecture for audiovisual 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 ser
5、vices 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 multimedia collaboration applications and services H.540H.549 Mobility interworking procedures H.550H.559Mobile multimedia collabor
6、ation inter-working procedures H.560H.569 BROADBAND AND TRIPLE-PLAY MULTIMEDIA SERVICES Broadband multimedia services over VDSL H.610H.619 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. H.361 (05/2006) i ITU-T Recommendation H.361 End-to-end quality of service (Qo
7、S) and service priority signalling in H.323 systems Summary This Recommendation defines the H.323 Quality of Service (QoS) and Service Priority signalling for exchanging, negotiating and controlling QoS and service priority parameters among the H.323 entities in a call. These calls may involve multi
8、ple network operator domains, multiple service domains, and heterogeneous transport mechanisms (e.g., mixed IP, ATM, and MPLS environments). In a single network operator domain or H.323 service domain, the QoS policies and mechanisms are usually homogenous and therefore the negotiation and establish
9、ment of QoS for a call is relatively simple. However, the same is relatively more complex when a call has to traverse multiple service or network domains each of which has its own set of policies and mechanisms. This Recommendation describes the QoS and priority signalling to enable a H.323-based ca
10、ll to acquire QoS irrespective of the number of domains it traverses. Source ITU-T Recommendation H.361 was approved on 29 May 2006 by ITU-T Study Group 16 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. H.361 (05/2006) FOREWORD The International Telecommunication Union (ITU)
11、 is the United Nations specialized agency in the field of telecommunications. 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 standardi
12、zing 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 Recommendations is covere
13、d 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 conciseness to indicat
14、e 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 Recommendation is achieved wh
15、en 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. INTELLECTUAL PROPER
16、TY 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, whether asserted
17、 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, implementors are cautioned that
18、 this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2006 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. H.361 (05/2006) iii CONTEN
19、TS Page 1 Scope 1 2 References. 1 2.1 Normative References 1 2.2 Informative References 1 3 Definitions 2 4 Abbreviations and Acronyms . 2 5 Architecture 3 5.1 The H.323 System 3 5.2 Functional Entities 4 6 QoS Parameters 4 6.1 Service Priority. 4 6.2 QoS Descriptor . 5 6.3 Traffic Descriptor . 6 6.
20、4 Authorization Parameters . 6 7 QoS Negotiation with the Network 6 7.1 Direct QoS Negotiation 6 7.2 Path-Coupled QoS Negotiation 6 7.3 Other QoS Negotiation. 7 8 H.323 QoS users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the
21、 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 Recommendation H.360 (2004), An ar
22、chitecture for end-to-end QoS control and signalling. ITU-T Recommendation Y.1221 (2002), Traffic control and congestion control in IP-based networks. ITU-T Recommendation Y.1541 (2006), Network performance objectives for IP-based services. IETF RFC 2205 (1997), Resource Reservation Protocol (RSVP)
23、Version 1 Functional Specification. 2 ITU-T Rec. H.361 (05/2006) IETF RFC 2474 (1998), Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers. IETF RFC 3312 (2002), Integration of Resource Management and Session Initiation Protocol (SIP). 2.2 Informative references I
24、ETF RFC 2998 (2000), A Framework for Integrated Services Operation over Diffserv Networks. 3 Definitions This Recommendation defines the following terms: 3.1 application plane: The H.323 application plane is made up of one or more H.323 service domains, each under the control of an H.323 end-user or
25、 H.323 Service Provider. 3.2 end user/endpoint: An entity employing application services. 3.3 network operator: An administrative entity operating a network. 3.4 network operator domain: A collection of network resources sharing a common set of policies, QoS mechanisms and technologies under the con
26、trol of a Network Operator. Network domain and network operator domain are used interchangeably. 3.5 network policy entity (NPE): A functional entity residing in a Network Domain that maintains the policies of the Network Operator. 3.6 QoS service manager (QoSM): A functional entity that mediates re
27、quests for end-to-end QoS in accordance with the policy determined by the QoSPE. It communicates with other QoSMs and with RMs to determine, establish and control the offered QoS. The QoSM will normally be the functionality within an H.323 gatekeeper and therefore is a H.323 service domain function.
28、 3.7 QoS policy entity (QoSPE): A functional entity that manages H.323 application policies and provides authorization of permitted and default QoS levels. It receives requests from and issues responses to QoSMs to establish the authorized end-to-end QoS levels. QoSPE may reside within the H.323 ser
29、vice domain or reside in a back-end policy server. 3.8 service domain: A Service Domain is a collection of physical or functional entities offering Application Services under the control of an Application Service Provider which share a consistent set of policies and common technologies. 3.9 transpor
30、t functionality (TF): A functional entity in the Network Domain representing the collection of transport resources within a Network Domain which is capable of QoS control. 3.10 transport plane: A collection of network operator domains. 3.11 transport resource manager (RM): A functional entity in the
31、 Network Domain that applies a set of policies and procedures to a set of transport resources to ensure that these are allocated to enable QoS guarantees across the domain of control of the RM. ITU-T Rec. H.361 (05/2006) 3 4 Abbreviations and acronyms This Recommendation uses the following abbreviat
32、ions: ACF Admission Confirm ARJ Admission Reject ARQ Admission Request BCF Bandwidth Confirm BRJ Bandwidth Reject BRQ Bandwidth Request DiffServ Differentiated Services DSCP Differentiated Service Code Point IntServ Integrated Services NPE Network Policy Entity QoS Quality of Service QoSM Quality of
33、 Service Manager QoSPE Quality of Service Policy Entity QST QoS Signalling Type RCF Registration Confirm RM Resource Manager RRJ Registration Reject RRQ Registration Request RSVP Resource ReSerVation Protocol (RFC 2205) TF Transport Functionality ToS Type of Service 5 Architecture The architecture f
34、or end-to-end QoS control and signalling is described in ITU-T Rec. H.360. The signalling components described in this Recommendation are based on the architecture therein. 5.1 The H.323 system In this Recommendation, the H.323 system is defined as the H.323 application plane and the associated tran
35、sport plane. The H.323 application plane is made up of one or more H.323 service domains, each under the control of an H.323 end-user or H.323 Service Provider. Examples of H.323 entities within the service domain are gatekeepers, gateways, H.323 endpoints, etc. The transport plane includes a number
36、 of separate network operator domains. The network operator domain consists of transport-related functionality that includes IP routers, switches, firewalls, etc. Each network domain may have its own QoS policies and/or differ from other domains in terms of administrative control (e.g., network oper
37、ator), QoS mechanisms (RSVP/IntServ, DiffServ, MPLS, etc.), access, metering, addressing schemes (global or local), transport protocol (IPv4 or IPv6), etc. 4 ITU-T Rec. H.361 (05/2006) 5.2 Functional entities The different functional entities in a H.323 system have been described in ITU-T Rec. H.360
38、 and shown in Figure 1: Figure 1/H.361 Relationship between QoS functional entities The two functional entities that are important to this discussion are the QoSM and the QoSPE. QoSM is the entity that mediates end-to-end QoS request in accordance with the policy determined by the QoSPE. The QoSPE i
39、s the entity that manages the application policies and provides authorization for QoS. The QoSPE and QoSM usually reside in the gatekeeper. The components are not usually called out individually in this Recommendation. 6 QoS parameters The QoS parameters necessary for H.323 QoS signalling include fo
40、ur main elements. These elements are: Service priority: Indicates the priority of the stream. QoS descriptor: Provides the QoS requirements for the stream. Traffic descriptor: Provides the traffic characteristics of the stream. Authorization parameters: Policy elements that authorize the request. Th
41、ese are described in greater detail below. 6.1 Service priority The service priority parameter is used to signal the priority of service to be provided to a bearer stream within an H.323 system. This priority parameter may be signalled between service providers, or between service providers and end
42、users. Media flows categorized as high priority shall take precedence over those categorized lower in priority with respect to the allocation of transport resource. The initiating endpoint/service provider shall determine the priority to be assigned to the media stream in both directions and signal
43、this to other service providers or endpoints involved in the call. ITU-T Rec. H.361 (05/2006) 5 Service Priority is an optional parameter and need not be included if routine priority is sufficient. If service priority is required, then it is signalled via the service priority parameter. The service
44、priority uses the following format: servicePrioritySignalled (boolean) This parameter shall specify whether service priority is to be signalled using the servicePriorityValue parameter. A false value indicates that the service priority is based on a value determined by a priori agreement between bus
45、iness entities. servicePriorityValue (enumeration) This parameter contains the requested service priority information that is used to signal the service priority between the H.323 entities. The description of this parameter will be further defined in a future annex of this Recommendation. The servic
46、e priority (servicePriority) parameter is added to the existing qosCapability parameter. 6.2 QoS descriptor The QoS descriptor contains the QoS requirements for the bearer stream. It is an optional parameter. If best effort service is sufficient, then the QoS descriptor parameter need not be include
47、d. The presence of a QoS descriptor indicates that better-than-best-effort service is required. The QoS descriptor includes a qosType followed by a qosValue. The elements of QoS descriptor are described in detail below. 6.2.1 Parameter QoSType The parameter QoSType indicates the strength of the QoS
48、request which guides the action to be taken in case of a QoS failure. In other words, it is used by the H.323 system to decide whether a call is to be continued or failed based on QoS failures. There are two possibilities with respect to the QoS type. They are: Desired: This indicates that QoS is de
49、sirable but not mandatory for the call. This means that the QoS request should be attempted but the call can continue even if the desired QoS is not granted. Required: This indicates that QoS is required and the call cannot continue if the required QoS for the stream is unavailable. 6.2.2 Parameter QoSValue The parameter QoSValue is used to specify the QoS requirements for the stream. The qosValue values may be left unspecified if they are to be derived from other sources such as static configurations and service level agreements.
