1、 International Telecommunication Union ITU-T G.8201TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (04/2011) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Packet over Transport aspects Quality and availability targets Error performance parameters and objectives for multi-ope
2、rator international paths within optical transport networks Recommendation ITU-T G.8201 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANS
3、MISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATION OF RADIOT
4、ELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPEC
5、TS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999 Ethernet over Transport aspects G.8000G.8099 MPLS over Transport aspects G.8100G.8199 Quality and availability targets G.8200G.8299Service Manag
6、ement G.8600G.8699 ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.8201 (04/2011) i Recommendation ITU-T G.8201 Error performance parameters and objectives for multi-operator international paths within optical transport networks Summa
7、ry Recommendation ITU-T G.8201 defines error performance parameters and objectives for international ODUk paths transported by the optical transport network (OTN), as described in Recommendation ITU-T G.709/Y.1331. While this Recommendation specifically addresses objectives for international ODUk pa
8、ths, the allocation principles can be applied to the design of error performance for national or private ODUk paths. This Recommendation is based upon a block-based measurement concept using error detection code (EDC) and EDC usage inherent to the path under test; the block repetition rate being in
9、accordance with OTN technology in accordance with Recommendation ITU-T G.709/Y.1331. This simplifies in-service measurements. The events, parameters and objectives are defined accordingly. In addition to path performance assessment, tandem connection monitoring is covered. History Edition Recommenda
10、tion Approval Study Group 1.0 ITU-T G.8201 2003-09-13 13 2.0 ITU-T G.8201 2011-04-13 15 Keywords Background block error (BBE), block-based concept, error detection code (EDC), EDC usage, error performance objectives, error performance parameters, hypothetical reference optical path (HROP), in-servic
11、e monitoring (ISM), optical channel data unit-k (ODUk) path, severely errored second (SES), tandem connection monitoring (TCM). ii Rec. ITU-T G.8201 (04/2011) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, informa
12、tion 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 on a world
13、wide 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 down in WT
14、SA 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 telecommunication adminis
15、tration 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 mandatory provis
16、ions 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 attention to
17、 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 others outsid
18、e 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 the late
19、st information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2012 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 G.8201 (04/2011) iii Table
20、 of Contents Page 1 Scope 1 1.1 Application of this Recommendation . 1 1.2 Transport network layers 1 1.3 Allocation of end-to-end performance . 2 2 References. 2 3 Terms and Definitions 3 4 Abbreviations 4 5 Measurement of the block 5 5.1 In-service monitoring . 5 5.2 Out-of-service measurements .
21、5 6 Performance monitoring at the near end and far end of a path . 6 7 Relationship between path performance monitoring and the block-based parameters . 6 7.1 General . 6 7.2 Estimation of the performance parameters . 7 7.3 Estimation of performance events at the far end of a path . 7 8 Error perfor
22、mance objectives . 7 8.1 End-to-end objectives . 7 8.2 Hypothetical reference optical path 8 8.3 Allocation of end-to-end performance objectives 9 Annex A Criteria for entry to and exit from the unavailable state 10 A.1 Criteria for a single direction 10 A.2 Criterion for a bidirectional path 10 A.3
23、 Criterion for a unidirectional path 10 A.4 Consequences on error performance measurements 11 Appendix I Flow chart illustrating the recognition of anomalies, defects, errored blocks, and SES . 12 Appendix II Example of OTN layer network trails 14 Bibliography. 15 Rec. ITU-T G.8201 (04/2011) 1 Recom
24、mendation ITU-T G.8201 Error performance parameters and objectives for multi-operator international paths within optical transport networks 1 Scope This Recommendation specifies error performance events, parameters and objectives for ODUk paths1of the optical transport network (OTN), as specified in
25、 ITU-T G.709. Clauses 1.1 to 1.3 give further details. 1.1 Application of this Recommendation This Recommendation is applicable to international paths of the optical transport network as described in ITU-T G.709. These paths are at the ODUk layer of the OTN, and are digital paths (see ITU-T G.709 fo
26、r a description of the ODUk layer). While this Recommendation specifically addresses objectives for international ODUk paths, the allocation principles can be applied to the design of error performance for national or private paths. The quality of client services, as well as the performance of the n
27、etwork elements belonging to the service layer, is outside of the scope of this Recommendation. However, ITU-T G.8201-based paths can carry various clients (e.g., SDH, ATM, GFP (i.e., IP, Ethernet, etc., encapsulated in GFP), etc.; see ITU-T G.709). ODUk paths meeting the objectives of this Recommen
28、dation will enable client layer traffic to meet its respective performance objectives. The error performance objectives are applicable to each direction of the ODUk path independently. The values apply end-to-end over a 27 500 km hypothetical reference path (see Figure 3). The performance of multipl
29、ex and cross-connect functions of client layers of the OTN (i.e., higher layers, above the OPUk, e.g., SDH, ATM, etc.; see ITU-T G.709 for a description of the OPUk) are not included in these values. The parameter definitions are block-based with the block repetition rate in accordance with OTN tech
30、nology, making in-service measurement convenient. In addition to in-service measurements, compliance with this Recommendation can be assessed using out-of-service measurements or estimated by measures compatible with this Recommendation as those specified in clause 7. The objectives given in this Re
31、commendation are long-term objectives to be met over an evaluation period of typically 30 consecutive days (one month). Shorter measurement periods required for maintenance and bringing-into-service are covered in b-ITU-T M.2401. 1.2 Transport network layers This Recommendation specifies the error p
32、erformance of ODUk paths in a given transport network layer. In the context of this Recommendation, an ODUk digital path is a trail carrying an OPUk payload and associated OPUk and ODUk overhead through the layered transport network between the path terminating equipment (see Figure 1). _ 1In this R
33、ecommendation, unless otherwise specified, the term path means ODUk path (k = 1, 2, or 3). The nominal ODUk rates are approximately 2.5 Gbit/s for ODU1, 10 Gbit/s for ODU2, and 40 Gbit/s for ODU3. 2 Rec. ITU-T G.8201 (04/2011) G.8201_F01PayloadOPUkODUkOHOHOH FECOTUkClient signal= OCh Payload unit= O
34、Ch Data unit k= OCh Transport unit kOptical carrier networkFigure 1 OTN signal structure The scope of application of this Recommendation is from path-end-point to path-end-point as illustrated in Figure 2. G.8201(11)_F02A BApplication of ITU-T G.8201ODUk path layer networkNOTE A and B are path end p
35、oints located at the path terminations as defined in ITU-T G.798. Figure 2 Application of ITU-T G.8201 for an end-to-end ODUk path 1.3 Allocation of end-to-end performance Allocations of end-to-end performance of ODUk paths are derived using the rules laid out in clause 8.3, which are length and com
36、plexity based. Detailed allocations of ITU-T G.8201 performance to the individual components (sections, multiplexers and cross-connects, etc.) are outside the scope of this Recommendation but, when such allocations are performed, the requirements of clause 8.3 should be met. 2 References The followi
37、ng 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; users of this Recomme
38、ndation 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 Recommendation does not gi
39、ve it, as a stand-alone document, the status of a Recommendation. Rec. ITU-T G.8201 (04/2011) 3 ITU-T G.709 Recommendation ITU-T G.709/Y.1331 (2009), Interfaces for the Optical Transport Network (OTN). ITU-T G.798 Recommendation ITU-T G.798 (2010), Characteristics of optical transport network hierar
40、chy equipment functional blocks. ITU-T G.826 Recommendation ITU-T G.826 (2002), End-to-end error performance parameters and objectives for international, constant bit-rate digital paths and connections. ITU-T G.827 Recommendation ITU-T G.827 (2003), Availability performance parameters and objectives
41、 for end-to-end international constant bit-rate digital paths. ITU-T G.828 Recommendation ITU-T G.828 (2000), Error performance parameters and objectives for international, constant bit-rate synchronous digital paths. ITU-T G.872 Recommendation ITU-T G.872 (2010), Architecture of optical transport n
42、etworks. ITU-T G.874 Recommendation ITU-T G.874 (2001), Management aspects of optical transport network elements. ITU-T I.356 Recommendation ITU-T I.356 (2000), B-ISDN ATM layer cell transfer performance. 3 Terms and Definitions This Recommendation defines the following terms: 3.1 error performance
43、events: In the following definitions, this Recommendation neither assumes nor requires that forward error correction (FEC) is used (see ITU-T G.709). However, if FEC is used, all the performance parameters and events are defined after FEC (i.e., post-FEC). In other words, the detection of the perfor
44、mance events (e.g., BBE, SES) is after any error correction. 3.1.1 errored block (EB): A block in which one or more bits are in error. 3.1.2 severely errored second (SES): A one-second period which contains 15% errored blocks or at least one defect (see Notes 1 and 2). NOTE 1 The defects and related
45、 performance criteria are listed in clause 7. NOTE 2 To simplify measurement processes, the defect is used in the definition of SES instead of defining SES directly in terms of severe errors affecting the path. While this approach simplifies the measurement of SES, it should be noted that there may
46、exist error patterns of severe intensity that would not trigger a defect as defined in clause 7. Thus, these would not be considered as an SES under this definition. If, in the future, such severe user-affecting events are found, this definition will have to be studied again. 3.1.3 background block
47、error (BBE): An errored block not occurring as part of an SES. 3.2 error performance parameters: Error performance should only be evaluated whilst the path is in the available state. For a definition of the entry/exit criteria for the unavailable state, see ITU-T G.827 and Annex A. In the following
48、definitions, this Recommendation neither assumes nor requires that forward error correction (FEC) is used (see ITU-T G.709). However, if FEC is used, all the performance parameters and events are defined after FEC (i.e., post-FEC). In other words, the detection of the performance events (e.g., BBE,
49、SES) is after any error correction. 3.2.1 severely errored second ratio (SESR): The ratio of SES in available time to total seconds in available time during a fixed measurement interval. 4 Rec. ITU-T G.8201 (04/2011) 3.2.2 background block error ratio (BBER): The ratio of BBE in available time to total blocks in available time during a fixed measurement interval. The count of total blocks excludes all blocks during SESs. 3.3 generic definition of the block: This Recommendation is b
