1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T Y.1291TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (05/2004) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT GENERATION NETWORKS Internet protocol aspects Architecture, access, network capabilities and resource managemen
2、t An architectural framework for support of Quality of Service in packet networks ITU-T Recommendation Y.1291 ITU-T Y-SERIES RECOMMENDATIONS GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT GENERATION NETWORKS GLOBAL INFORMATION INFRASTRUCTURE General Y.100Y.199 Services, applic
3、ations and middleware Y.200Y.299 Network aspects Y.300Y.399 Interfaces and protocols Y.400Y.499 Numbering, addressing and naming Y.500Y.599 Operation, administration and maintenance Y.600Y.699 Security Y.700Y.799 Performances Y.800Y.899 INTERNET PROTOCOL ASPECTS General Y.1000Y.1099 Services and app
4、lications Y.1100Y.1199 Architecture, access, network capabilities and resource management Y.1200Y.1299 Transport Y.1300Y.1399 Interworking Y.1400Y.1499 Quality of service and network performance Y.1500Y.1599 Signalling Y.1600Y.1699 Operation, administration and maintenance Y.1700Y.1799 Charging Y.18
5、00Y.1899 NEXT GENERATION NETWORKS Frameworks and functional architecture models Y.2000Y.2099 Quality of Service and performance Y.2100Y.2199 Service aspects: Service capabilities and service architecture Y.2200Y.2249 Service aspects: Interoperability of services and networks in NGN Y.2250Y.2299 Numb
6、ering, naming and addressing Y.2300Y.2399 Network management Y.2400Y.2499 Network control architectures and protocols Y.2500Y.2599 Security Y.2700Y.2799 Generalized mobility Y.2800Y.2899 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. Y.1291 (05/2004) i ITU-T Recom
7、mendation Y.1291 An architectural framework for support of Quality of Service in packet networks Summary This Recommendation provides an architectural framework for support of Quality of Service (QoS) in packet networks. Central to the architectural framework is a set of generic network mechanisms (
8、or QoS building blocks) for controlling the network service response to a service request, which can be specific to a network element, or for signalling between network elements, or for controlling and administering traffic across a network. Distributed across three logical planes (namely the Contro
9、l Plane, Data Plane and Management Plane), the building blocks can be used in combination to form various approaches for delivering the satisfactory collective effect of varying service performance required by a range of applications, such as file transfer and multimedia conferencing. Source ITU-T R
10、ecommendation Y.1291 was approved on 7 May 2004 by ITU-T Study Group 13 (2001-2004) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. Y.1291 (05/2004) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The I
11、TU 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 worldwide basis. The World Telecommunication Standardi
12、zation 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 WTSA Resolution 1. In some areas of information tec
13、hnology 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 administration and a recognized operating agency. Compli
14、ance 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 provisions are met. The words “shall“ or some other oblig
15、atory 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 RIGHTS ITU draws attention to the possibility that the practice or implementatio
16、n 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 of the Recommendation development process. As of
17、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 this may not represent the latest information and are therefore strongly urged to
18、consult the TSB patent database. ITU 2004 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. Y.1291 (05/2004) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 2 4 Abbreviations and acronyms 2 5
19、 Introduction 2 6 QoS building blocks . 3 7 Control-plane mechanisms . 4 7.1 Admission control 4 7.2 QoS routing 5 7.3 Resource reservation 6 8 Data-plane mechanisms 6 8.1 Queue (or buffer) management 6 8.2 Congestion avoidance. 7 8.3 Queuing and scheduling . 8 8.4 Packet marking . 8 8.5 Traffic cla
20、ssification. 8 8.6 Traffic policing. 9 8.7 Traffic shaping 9 9 Management-plane mechanisms. 9 9.1 Service level agreement 9 9.2 Traffic metering and recording. 9 9.3 Traffic restoration. 10 9.4 Policy 10 10 Interactions among building blocks 10 10.1 QoS signalling 11 10.2 Intra-plane. 12 10.3 Inter-
21、plane. 12 11 Security considerations. 12 11.1 Data plane. 12 11.2 Management and control plane 12 11.3 QoS Signalling 13 12 Example approaches . 13 12.1 IntServ 13 12.2 DiffServ 14 12.3 MPLS 14 12.4 IPCablecom dynamic QoS . 14 Annex A Traffic priority levels. 15 iv ITU-T Rec. Y.1291 (05/2004) Page A
22、ppendix I A comprehensive QoS approach based on independent resource control 17 I.1 Implementation flexibility for packet networks with MPLS support. 18 I.2 Implementation flexibility for packet networks without MPLS support 18 I.3 Implementation flexibility for distributed resource control . 19 App
23、endix II Priority promotion scheme . 19 BIBLIOGRAPHY 20 ITU-T Rec. Y.1291 (05/2004) 1 ITU-T Recommendation Y.1291 An architectural framework for support of Quality of Service in packet networks 1 Scope This Recommendation provides an architectural framework for support of Quality of Service (QoS) in
24、 packet networks. Central to the architectural framework is a set of QoS building blocks distributed across three logical planes (namely the Control Plane, Data Plane and Management Plane) to control network performance, even in case of network resource contention. Ultimately the building blocks are
25、 to help deliver “the collective effect of service performance which determines the degree of satisfaction of a user of the service“. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommen
26、dation. 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 other reference
27、s 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 E.360.1 (2002), Framework for QoS routing and related t
28、raffic engineering methods for IP-, ATM- and TDM-based multiservice networks. ITU-T Recommendation E.360.2 (2002), QoS routing and related traffic engineering methods Call routing and connection routing methods. ITU-T Recommendation E.360.3 (2002), QoS routing and related traffic engineering methods
29、 QoS resource management methods. ITU-T Recommendation E.360.4 (2002), QoS routing and related traffic engineering methods Routing table management methods and requirements. ITU-T Recommendation E.360.5 (2002), QoS routing and related traffic engineering methods Transport routing methods. ITU-T Reco
30、mmendation E.360.6 (2002), QoS routing and related traffic engineering methods Capacity management methods. ITU-T Recommendation E.360.7 (2002), QoS routing and related traffic engineering methods Traffic engineering operational requirements. ITU-T Recommendation E.361 (2003), QoS routing support fo
31、r interworking of QoS service classes across routing technologies. ITU-T Recommendation E.860 (2002), Framework of a service level agreement. ITU-T Recommendation G.114 (2003), One-way transmission time. ITU-T Recommendation G.1000 (2001), Communications Quality of Service: A framework and definitio
32、ns. ITU-T Recommendation G.1010 (2001), End-user multimedia QoS categories. ITU-T Recommendation I.350 (1993), General aspects of quality of service and network performance in digital networks, including ISDNs. 2 ITU-T Rec. Y.1291 (05/2004) ITU-T Recommendation J.112 (1998), Transmission systems for
33、 interactive cable television services. ITU-T Recommendation J.162 (2004), Network call signalling protocol for the delivery of time-critical services over cable television networks using cable modems. ITU-T Recommendation J.163 (2004), Dynamic quality of service for the provision of real-time servi
34、ces over cable television networks using cable modems. ITU-T Recommendation J.170 (2002), IPCablecom security specification. ITU-T Recommendation J.174 (2002), IPCablecom interdomain quality of service. ITU-R Recommendation M.1079-2 (2003), Performance and quality of service requirements for Interna
35、tional Mobile Telecommunications-2000 (IMT-2000) access networks. ITU-T Recommendation X.805 (2003), Security architecture for systems providing end-to-end communications. ITU-T Recommendation Y.1221 (2002), Traffic control and congestion control in IP-based networks. ITU-T Recommendation Y.1540 (20
36、02), Internet protocol data communication service IP packet transfer and availability performance parameters. ITU-T Recommendation Y.1541 (2002), Network performance objectives for IP-based services. 3 Definitions This Recommendation does not define new terms. 4 Abbreviations and acronyms This Recom
37、mendation uses the following abbreviations: DiffServ Differentiated Services DQoS Dynamic QoS IETF Internet Engineering Task Force IntServ Integrated Services ITU-T International Telecommunication Union Telecommunication Standardization Sector LSP Label Switched Path MPLS Multi-Protocol Label Switch
38、ing MTA Multimedia Terminal Adaptor QoS Quality of Service RSVP Resource ReSerVation Protocol SLA Service Level Agreement 5 Introduction Quality of Service (QoS) ultimately is about supporting the characteristics and properties of specific applications. Yet different applications may have quite diff
39、erent needs. For example, for telemedicine, the accuracy of the delivery is more important than overall delay or packet delay ITU-T Rec. Y.1291 (05/2004) 3 variation (i.e., jitter), while for IP telephony, jitter and delay are key and must be minimized. A number of ITU-T Recommendations deal with Qo
40、S. ITU-T Rec. E.800 defines QoS as “the collective effect of service performance which determines the degree of satisfaction of a user of the service“. Given that ITU-T Rec. E.800 considers support, operability, serviceability and security all part of service performance, this QoS definition is comp
41、rehensive in scope. Expanding on the E.800 QoS concept, ITU-T Rec. G.1000 breaks down service performance (or service quality) into functional components and links it to network performance such as defined in ITU-T Recs I.350, Y.1540 and Y.1541. Complementary to ITU-T Rec. G.1000, which gives a fram
42、ework, ITU-T Rec. G.1010 provides end-user-centric application requirements in terms of broad categories (such as interactive, error tolerant). Concerning specific applications or performance parameters, among related standards, ITU-R Rec. M.1079-2 defines the end-to-end speech and data quality and
43、performance requirements for IMT-2000 access networks, while ITU-T Rec. G.114 specifies the bounds for transmission time for connections across a digital network. To deliver required network performance, certain mechanisms need to be in place within the network. These network mechanisms are to contr
44、ol and deliver various network service responses, even in case of network resource contention. IETF RFC 2990 summarizes the possible characteristics of the controlled service response to a specific service request: consistent and predictable, at a level equal to or above a guaranteed minimum, or est
45、ablished in advance. For example, in case of network resource contention or congestion, to maintain the expected service response requires a variety of means working at different time-scales, from those for careful network planning based on traffic patterns over a long period to those for differenti
46、al resource allocation and admission control based on the current network load condition. These and other mechanisms (e.g., a signalling method for indicating the desired level of network performance) are the focus of the architectural framework for QoS support. In particular, this Recommendation id
47、entifies a set of generic QoS network mechanisms and provides a structure for them. Ultimately the network mechanisms are to be used in combination to deliver the satisfactory collective effect of varying service performance required by a wide range of applications. The application-independent aspec
48、t of the identified architectural framework distinguishes it from application-specific QoS architectures such as defined in ITU-T Rec. H.360, which is specific to multimedia applications. 6 QoS building blocks Key to the QoS architectural framework is a set of generic network mechanisms for controll
49、ing the network service response to a service request, which can be specific to a network element, or for signalling between network elements, or for controlling and administering traffic across a network. (Please note that the building blocks should not be deemed end to end.) As depicted in Figure 1, the building blocks are organized into three planes: Control Plane, which contains mechanisms dealing with the pathways through which user traffic travels. These mechanisms include admission contr
