1、 International Telecommunication Union ITU-T Y.1545TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (05/2013) SERIES Y: INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Internet protocol aspects Quality of service and network performance Roadmap for the quality of se
2、rvice of interconnected networks that use the Internet protocol Recommendation ITU-T Y.1545 ITU-T Y-SERIES RECOMMENDATIONS GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS GLOBAL INFORMATION INFRASTRUCTURE General Y.100Y.199 Services, applications and middlew
3、are 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 applications Y.1100Y.
4、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.1599Signalling Y.1600Y.1699 Operation, administration and maintenance Y.1700Y.1799 Charging Y.1800Y.1899 IPTV over
5、NGN Y.1900Y.1999 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.2
6、299 Numbering, naming and addressing Y.2300Y.2399 Network management Y.2400Y.2499 Network control architectures and protocols Y.2500Y.2599 Packet-based Networks Y.2600Y.2699 Security Y.2700Y.2799 Generalized mobility Y.2800Y.2899 Carrier grade open environment Y.2900Y.2999 FUTURE NETWORKS Y.3000Y.34
7、99 CLOUD COMPUTING Y.3500Y.3999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T Y.1545 (05/2013) i Recommendation ITU-T Y.1545 Roadmap for the quality of service of interconnected networks that use the Internet Protocol Summary Recommendation ITU-T Y.1545 is intend
8、ed as a guide to help regulators and network service providers meet QoS performance objectives. Traditional packet networks have been built under the principle that networks will operate on the basis of an unguaranteed best-effort packet delivery. The best effort paradigm has been spectacularly succ
9、essful in supporting non-real-time data applications (e.g., email and file transfer); this principle assigns the responsibility for detecting and correcting transmission problems to the customer equipment and higher-level protocols that require better network support. However, the best-effort delive
10、ry principle does not provide a reliable quality of user experience in interactive voice telephony and other demanding real-time applications when network bandwidth limitations increase considerably delay, jitter and packet loss. These applications work best across networks that can deliver “better
11、than best-effort“ performance for various characteristics. History Edition Recommendation Approval Study Group 1.0 ITU-T Y.1545 2013-05-14 12 Keywords Network service provider, NSP, quality of service, QoS, QoS classes. ii Rec. ITU-T Y.1545 (05/2013) FOREWORD The International Telecommunication Unio
12、n (ITU) 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 an
13、d issuing 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 the
14、se topics. 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 Recommendation, the expr
15、ession “Administration“ is used for conciseness 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 applicab
16、ility) and compliance with the Recommendation 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
17、Recommendation is required of any party. INTELLECTUAL 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 applicabili
18、ty of claimed Intellectual Property Rights, 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 t
19、his Recommendation. However, implementers 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 2013 All rights reserved. No part of this publication may be reproduced, by any means wh
20、atsoever, without the prior written permission of ITU. Rec. ITU-T Y.1545 (05/2013) iii Table of Contents Page 1 Scope 1 2 References. 1 3 Terms and definitions . 1 3.1 Terms and definitions defined elsewhere . 1 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acronyms 2 5 Convention
21、s 3 6 Basic reference architecture 3 7 Guidelines . 4 7.1 QoS parameters 4 7.2 Quality of service (QoS) classes and network performance objectives . 4 7.3 Packet marking . 5 7.4 Packet handling 5 7.5 Network performance . 5 7.6 Performance measurement . 5 7.7 Performance monitoring . 6 7.8 Reporting
22、 7 7.9 Publication 7 Appendix I Mapping between DiffServ, MPLS and Ethernet 8 Appendix II Sharing of bearer QoS budgets . 9 Rec. ITU-T Y.1545 (05/2013) 1 Recommendation ITU-T Y.1545 Roadmap for the quality of service of interconnected networks that use the Internet Protocol 1 Scope This Recommendati
23、on: Recommends performance objectives of packet-based networks accepted across a UNI for each defined packet network QoS class, addressing “end-to-end network“ or bearer QoS. Recommends packet marking and handling mechanisms designed for indicating the accepted packet network QoS class for a given i
24、ncoming IP packet on a UNI or NNI. Addresses procedures for the measurement of the QoS performance of packet-based networks, namely MPLS, Ethernet and IP. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provis
25、ions 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 encouraged to investigate the possibility of applying the most recent edition of the Recommendation
26、s 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 E.800 Recommendation ITU-T E.800 (2008), Definiti
27、ons of terms related to quality of service. ITU-T Y.1540 Recommendation ITU-T Y.1540 (2011), Internet protocol data communication service-IP packet transfer and availability performance parameters. ITU-T Y.1541 Recommendation ITU-T Y.1541 (2011), Network performance objectives for IP-based services.
28、 ITU-T Y.1543 Recommendation ITU-T Y.1543 (2007), Measurements in IP networks for inter-domain performance assessment. IETF RFC 3432 IETF RFC 3432 (2002), Network performance measurement with periodic streams. 3 Terms and definitions 3.1 Terms and definitions defined elsewhere This Recommendation us
29、es the following terms defined elsewhere: 3.1.1 IP packet loss ratio ITU-T Y.1540: The ratio of total lost IP packets to total transmitted packets in a population of interest. 3.1.2 interconnection ITU-T E.800: Is the physical and logical linking of public communications networks used by the same or
30、 a different service provider in order to allow the users of one service provider to communicate with users of another service provider, or to access services provided by another service provider. 2 Rec. ITU-T Y.1545 (05/2013) 3.1.3 measurement point ITU-T Y.1540: The boundary between a host and an
31、adjacent link at which performance reference events can be observed and measured. Consistent with b-ITU-T I.353, the standard Internet protocols can be observed at IP measurement points. b-ITU-T I.353 provides more information about MPs, for digital services. 3.1.4 network performance ITU-T E.800: I
32、s the ability of a network or network portion to provide the functions related to communications between users. 3.1.5 populations of interest ITU-T Y.1540: For the end-to-end case, the population of interest is usually the total set of packets being sent from SRC to DST. The measurement points in th
33、e end-to-end case are the MP-UNIs at the SRC and DST as shown in Figure 1. 3.1.6 quality of service ITU-T E.800: Is the totality of characteristics of a telecommunications service that bear on its ability to satisfy stated and implied needs of the user of the service. 3.1.7 service level agreement I
34、TU-T E.800: Is a formal document listing a set of performance characteristics and target values (or range) to be delivered for a service or portfolio of services by the service provider. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 host: A host is a
35、 computer that communicates using the Internet protocols. A host implements routing functions (i.e., it operates at the IP layer) and may implement additional functions including higher layer protocols (e.g., TCP in a source or destination host) and lower layer protocols (e.g., ATM). 3.2.2 IP packet
36、 delay variation (IPDV): The difference between the actual IPTD of a packet and a reference IPTD for a packet population of interest. IPDV is also referred to as “jitter“, and is usually reported in milliseconds. 3.2.3 IP packet transfer delay (IPTD): The one-way time interval between the moment the
37、 first bit of an IP packet crosses the MP at the source (entry point of a network) and the moment the last bit of the same packet crosses an MP at the destination (exit point of the network). IPTD is also referred to as “delay“ or “latency“. 3.2.4 network service provider: An organization that provi
38、des Internet access to Internet service providers. A network service provider offers a direct access to the Internet backbone, network services or interexchange carriers. 3.2.5 packet network: A network that uses the Internet protocol or other similar frame-based protocols such as Ethernet and MPLS.
39、 3.2.6 parameter: A quantifiable characteristic of a service with specified scope and boundaries. 3.2.7 probing packet: An individual IP packet associated with active performance testing, i.e., a test packet ITU-T Y.1543. 4 Abbreviations and acronyms This Recommendation uses the following abbreviati
40、ons and acronyms: AF Assured Forward DF Default Forward DiffServ Differentiated Service DSCP Differentiated Service Code Point EF Expedited Forward Rec. ITU-T Y.1545 (05/2013) 3 ER Edge Router IP Internet Protocol IPDV IP Delay Variation IPLR IP Packet Loss Ratio IPTD IP Transfer Delay LAN Local Are
41、a Network MP Measurement Point MPLS Multiprotocol Label Switching MS Microsoft MTU Maximum Transmission Unit NNI Network-to-Network Interface NP Network Performance NS Network Section NSP Network Service Provider PHP Per Hop Behaviour QoS Quality of Service SLA Service Level Agreement TE Terminal Eq
42、uipment UNI User Network Interface UTC Universal Coordinated Time VLAN ID Virtual Local Area Network Identification VoIP Voice over IP VTC Video Teleconference 5 Conventions None. 6 Basic reference architecture The performance objectives in this Recommendation are expected to be measured over packet
43、s in a population of interest that enter a network at a source user-network interface (UNI), travel along a path through one or more concatenated packet network sections, and exit through a destination UNI, possibly connected to a different network, as depicted in Figure 1. 4 Rec. ITU-T Y.1545 (05/2
44、013) Y.1545(13)_F01ER ER ERER ER ERTE TEIP network cloud (may be comprised of network sections belonging to oneor more network operators)Network section Network section Network sectionEnd-to-end packet network (Network QoS)Customer installation Customer installationUNI UNINNI NNIMP-UNI MP-NNI MP-NNI
45、 MP-NNI MP-UNIMP-NNIFigure 1 End-to-end packet network ITU-T Y.1541 A network service provider (NSP) is expected to only measure its own network section (UNI-to-NNI or NNI-to-NNI), and rely on reports from other interconnected NSPs to derive the UNI-to-UNI performance likely to be experienced by an
46、end-users traffic. 7 Guidelines 7.1 QoS parameters This Recommendation considers the following quality of service parameters: IPTD (IP transfer delay) IPDV (IP delay variation) sometimes referred as jitter IPLR (IP packet loss ratio) 7.2 Quality of service (QoS) classes and network performance objec
47、tives The QoS classes and related performance objectives for packet-based networks to be applied by NSPs are described in Table 1. Table 1 QoS classes of packet networks ITU-T Y.1541 QoS Class Applications Network performance parameter Comments IPTD IPDV IPLR Class 0 Voice over IP (VoIP) video telec
48、onference (VTC) 100 ms 50 ms 103PSTN-quality VoIP (or voice telephony) Real-time, jitter sensitive, high interaction Class 1 Voice over IP (VoIP) video teleconference (VTC) 400 ms 50 ms 103Satellite-quality VoIP Real-time, jitter sensitive, interactive Class 2 Transaction data 100 ms U 103Signalling
49、 Highly interactive Class 3 Transaction data 400 ms U 103Business data (e.g., e-banking) Interactive Rec. ITU-T Y.1545 (05/2013) 5 Table 1 QoS classes of packet networks ITU-T Y.1541 QoS Class Applications Network performance parameter Comments IPTD IPDV IPLR Class 4 Video streaming 1 s U 103File transfer Low loss only (short transactions) Class 5 Traditional applications of default IP networks U U U Best effort NOTE U means “unspecified“ or “unbounded“. For m
