1、 International Telecommunication Union ITU-T Y.1543TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (11/2007) SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Internet protocol aspects Quality of service and network performance Measurements in IP net
2、works for inter-domain performance assessment Recommendation ITU-T Y.1543 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 middleware Y.200Y.299 Net
3、work 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.1199 Architecture,
4、 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.1800Y.1899 NEXT GENERATION NETWORKS Fr
5、ameworks 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 Numbering, naming and addressing Y.2300Y
6、.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. Rec. ITU-T Y.1543 (11/2007) i Recommendation ITU-T Y.1543 Measurements in IP
7、networks for inter-domain performance assessment Summary Recommendation ITU-T Y.1543 specifies a set of IP performance parameters and methods of measurement applicable when assessing the quality of packet transfer on inter-domain paths. The methods anticipate that there will be multiple measurement
8、systems, each conducting measurements of a segment of the customer-to-customer path, and recommend configurations that should produce useful results in this cooperative scenario. The methods rely on existing parameter definitions and encompass both active and passive measurement techniques. Source R
9、ecommendation ITU-T Y.1543 was approved on 13 November 2007 by ITU-T Study Group 12 (2005-2008) under Recommendation ITU-T A.8 procedure. ii Rec. ITU-T Y.1543 (11/2007) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunication
10、s, 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 view to standardizing telecommunications
11、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 covered by the procedure laid
12、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 indicate both a telecommunicati
13、on 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 when all of these mandator
14、y 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 PROPERTY RIGHTS ITU draws atte
15、ntion 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 by ITU members or other
16、s 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 are cautioned that this may not represent
17、the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2008 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T Y.1543 (11/2007) i
18、ii CONTENTS Page 1 Scope 1 2 References. 2 3 Terms and definitions . 3 4 Abbreviations and acronyms 3 5 Performance attributes 5 5.1 Mean one-way delay. 6 5.2 One-way packet delay variation . 6 5.3 Packet loss ratio 7 5.4 Path unavailability 7 6 Performance measurement requirements 8 6.1 Active meas
19、urement requirements . 9 6.2 Passive measurement requirements 11 6.3 Measurement time-escales 11 6.4 Measurement system unavailability . 12 6.5 Interaction of policing and performance measurement 12 6.6 Clock synchronization 13 6.7 Measurement granularity 16 7 Measurement network model . 17 7.1 Netw
20、ork partitioning 18 7.2 Applied measurements . 22 8 Measurement procedures 29 8.1 Active measurement procedures. 29 8.2 Passive measurement procedures . 31 9 Areas for further study and future work . 31 10 Security considerations. 31 10.1 Impact of security on measurement of performance 31 10.2 Impa
21、ct of performance measurement on security 31 Appendix I Summary of performance objectives and measurements. 32 Appendix II Generic inter-domain management process for measurement systems 34 Bibliography. 35 iv Rec. ITU-T Y.1543 (11/2007) Introduction Network performance expectations must be set and
22、monitored among users and service providers to raise confidence in network delivery. Users typically only see the end-to-end performance, i.e., the concatenation of performance over multiple network segments and/or across multiple heterogeneous service providers. Thus, meaningful discussions of netw
23、ork quality of service (QoS) between users and service providers are most relevant on an end-to-end basis. Existing standards specify several metrics and measurement methods for point-to-point performance. Notable are Recommendations ITU-T Y.1540 and Y.1541 and the IETF IP Performance Metrics (IPPM)
24、 Working Group standards. However, many options and parameters are left unspecified, as are mapping between IP and non-IP metrics, accuracy and data handling. Each of these topics must be specified in order to support QoS across multiple heterogeneous service providers. Therefore, this Recommendatio
25、n specifies the essential measurement options, so that performance measurements conducted by operators in their administrative domains can be easily combined to estimate the end-to-end network performance or the inter-domain QoS. Rec. ITU-T Y.1543 (11/2007) 1 Recommendation ITU-T Y.1543 Measurements
26、 in IP networks for inter-domain performance assessment 1 Scope This Recommendation describes measurements which are applicable for: 1) Providers delivery assurance of customers network performance. 2) Providers to supply performance information for prospective customers. 3) Providers troubleshootin
27、g among their networks along defined paths. 4) Providers internal indication of performance impact of changes within their networks. 5) Providers monitoring of each others network performance. 6) Providing information to other NGN components, e.g., RACF, bandwidth broker, OSS/BSS, etc. The scope of
28、this Recommendation covers active and passive measurement and combinations of these two techniques. Active measurement employs packets dedicated to the measurement function inserted at one measurement point and collected at a remote measurement point. Passive measurement usually involves observation
29、s of user packet traffic at one or more measurement points. Spatial measurement is a special category of active measurement that employs both active and passive techniques. It utilizes observations of measurement-dedicated packets at three or more measurement points, where one or more point(s) simpl
30、y monitor(s) (and do(es) not terminate) the test packets. This Recommendation presents requirements for performance measurements including performance attributes and time-escales. Building upon existing standards, it recommends best practice in these areas based on ITU-T Y.1540. Comparisons to other
31、 standards (IETF RFCs) are included. Defining the probe packet format is beyond the scope of this Recommendation. This Recommendation describes a network model which locates key points of demarcation and measurement. It categorizes various measurements and shows how they may be applied to the networ
32、k model. It reviews time synchronization and sets targets for equipment which is located at various points in the network model. Security requirements of the measurement traffic are analysed, approaches are considered, and then a set of approaches are picked. Security of BGP, synchronization systems
33、 and customer equipment are beyond the scope of this Recommendation. Customer interactions with their service provider are discussed at a high level. Details of transferring results to customers are beyond the scope of this Recommendation. The target networks of this Recommendation are IP networks a
34、nd MPLS-enabled IP networks, pure L2 and other non-native IP networks are out of its scope. This Recommendation describes how to measure the minimally required set of metrics to describe the performance of networks. Specification of advanced analysis and dissemination of measurement data are beyond
35、the scope of this Recommendation. Impairment allocation and mapping performance among IP and non-IP networks are beyond the scope of this Recommendation. Methods to determine the exact network path that packets will follow are beyond the scope of this Recommendation. 2 Rec. ITU-T Y.1543 (11/2007) 2
36、References The following ITU-T Recommendations and 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;
37、 users of this Recommendation are therefore encouraged 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 Reco
38、mmendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T G.107 Recommendation ITU-T G.107 (2005), The E-model, a computational model for use in transmission planning. ITU-T O.211 Recommendation ITU-T O.211 (2006), Test and measurement equipment to perform tests a
39、t the IP layer. ITU-T P.800 Recommendation ITU-T P.800 (1996), Methods for subjective determination of transmission quality. ITU-T X.805 Recommendation ITU-T X.805 (2003), Security architecture for systems providing end-to-end communications. ITU-T Y.1540 Recommendation ITU-T Y.1540 (2007), Internet
40、 protocol data communication service IP packet transfer and availability performance parameters. ITU-T Y.1541 Recommendation ITU-T Y.1541 (2006), Network performance objectives for IP-based services. ITU-T Y.1711 Recommendation ITU-T Y.1711 (2004), Operation see clause 7 of ITU-T Y.1540 for details
41、on the service availability function. A period is considered unavailable if there is an excessive packet loss ratio (PLR) (e.g., 75%) over a specific fixed time interval. The interval may be set independently for each QoS class, but currently only one interval is specified, 5 minutes. 8 Rec. ITU-T Y
42、.1543 (11/2007) This definition is intended to capture periods of very poor performance and requires the network performance to return to normal levels before the unavailability is ended. During a period of unavailability, none of the delay or delay variation metrics are valid. Path period unavailab
43、ility (IPUA) is measured by summing the periods of unavailability and dividing by the total period being covered. The period being covered to be used is the default “reporting to customer“ period. It should be noted that the IDQ system keeps track of each individual period of unavailability for repo
44、rting to customers. Unavailability is largely insensitive to distance, but is sensitive to single points of failure in a network architecture. It will vary significantly with access technologies and configurations. To achieve a low level of unavailability, diverse transmission paths are required. 5.
45、4.1 Relationship to existing standards b-IETF RFC 2678 defines parameters for unidirectional connectivity and bidirectional instantaneous connectivity. Both these metrics can be used to assess connectivity over time, similar to the Y.1540 service availability function. 6 Performance measurement requ
46、irements Inter-domain QoS is intended to increase the level of confidence in the expected service characteristics of the NGN. Increased confidence will enable new applications, services and revenue streams. An integral part of achieving this confidence is the continuous measurement of service perfor
47、mance. The purpose of taking measurements is to provide information for customers, potential customers and service providers, and includes: 1) For customers and potential customers: a) Reports to customers of what service has been delivered. b) Reports to potential customers to support marketing cla
48、ims on service characteristics. 2) For service providers and third party delivery assurance entities: a) Reports to design service offerings. b) Reports for troubleshooting. c) Data for marketing collateral. d) Reports to enable capacity planning and service development. The IDQ measurement system a
49、nd the statistics that it produces must: a) be easily understood by SPs and customers; b) be well defined (non-ambiguous); c) be relevant to customers applications; d) enable service providers to diagnose issues and anticipate capacity requirements; e) be independently repeatable (multiple SP measurements over the same time get the same result); f) be independently verifiable by customers (customer measurements should be close to SP estimates); g) be widely applicable (traffic type, link size, load independent, any IP network); h)
