ITU-T M 2102-2000 Maintenance thresholds and procedures for recovery mechanisms (protection and restoration) of international SDH VC trails (paths) and multiplex sections (Study Gr.pdf

1、 STD-ITU-T RECNN M-ZLOZ-ENGL ZOOU R 4862571 Oh88904 754 INTERNATIONAL TELECOMMU N CATION UNION ITU=T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU M.2102 (O 2/2 o 00) SERIES M: TMN AND NETWORK MAINTENANCE: INTERNATIONAL TRANSMISSION SYSTEMS, TELEPHONE CIRCUITS, TELEGRAPHY, FACSIMILE AND LEASED CIR

2、CUITS International transport network Maintenance thresholds and procedures for recovery mechanisms (protection and restoration) of international SDH VC trails (paths) and multiplex sections ITU-T Recommendation M.2102 (Formerly CCITT Recommendation) STD-ITU-T RECMN M-2102-ENGL 2000 = 4862591 Ob8890

3、5 690 ITU-T M-SERIES RECOMMENDATIONS TMN AND NETWORK MAINTENANCE: INTERNATIONAL TRANSMISSION SYSTEMS, TELEPHONE CIRCUITS, TELEGRAPHY, FACSIMILE AND LEASED CIRCUITS Introduction and general principles of maintenance and maintenance organization International transmission system International telephon

4、e circuits Common channel signalling systems International telegraph systems and phototelegraph transmission International leased group and supergroup links International leased circuits Mobile telecommunication system and services Intemational public telephone network Intemational data transmission

5、 systems M.l SM.299 M.300-M.559 M.560-M.759 M.760-M.799 M.800-M.899 M.900-M.999 M. 1 000-M. 1099 M.1100-M.1199 M.1200-M.1299 M.1300-M.1399 M. 1400-M. 1999 ecommumcations management netwo M.3000-M.3599 Integrated services digital networks Common channel signalling systems M.3600-M.3999 M.4000-M.4999

6、For further details, please refer to the list of TU-TRecommendations. STD-ITU-T RECMN M-ZLOZ-ENGL ZOO 4862572 0688906 527 I ITU-T Recommendation M.2102 Maintenance thresholds and procedures for recovery mechanisms (protection and restoration) of international SDH VC trails (paths) and multiplex sect

7、ions Summary This ITU-T Recommendation defines maintenance thresholds and procedures for recovery mechanisms of international SDH VC trails (paths), multiplex sections (MSs) and subnetwork connections (SNCs), in case of failure, degradation, maintenance activities (e.g. planned outages). This Recomm

8、endation deals with protection and restoration including return to original configuration. The internal protection capabilities of network element (NE) hardware are outside the scope of this Recommendation. Maintenance thresholds and procedures given in this Recommendation are only used for protecti

9、on and restoration of VCs trails (path), multiplex sections and subnetwork connections (SNCs) . Source ITU-T Recommendation M.2 102 was prepared by ITU-T Study Group 4 (1997-2000) and approved under the WTSC Resolution 1 procedure on 4 February 2000. Keywords Acceptable state, alternative trail (pat

10、h), automatic protection (revertive), automatic protection (non-revertive), automatic restoration (revertive), automatic restoration (non-revertive), manual protection (revertive), manual protection (non-revertive), manual restoration (revertive), manual restoration (non-revertive), multiplex sectio

11、n, normal, normalization, VC trail (path), patch, protection, recovery initiation, recovery mechanism, re-routing trail, restoration, subnetwork connection, SDH, service trail, switch, working trail. For a definition of subnetwork connections, see ITU-T Recommendation G.803 2. FOREWORD The Internati

12、onal Telecommunication Union (ITU) 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 Recommendation

13、s on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), 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 approva

14、l of ITU-T Recommendations is covered by the procedure laid down in WTSC Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation, the expression “Administration

15、“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. 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

16、. 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 the date of approval of this Recommendation, ITU had not received notice of intellect

17、ual 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 consult the TSB patent database. o ITU 2001 All rights reserved. No part of this publ

18、ication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing fi-om ITU. 1 2 3 4 5 5.1 5.2 6 6.1 6.2 6.3 6.4 6.5 Scope References Terms and definitions . Abbreviations . Recovery mechanisms for interna

19、tional multiplex sections . Multiplex section protection . Forced switching to altemative MS Switching time (automatic switching) . (revertive) Multiplex section restoration 5.1.1 5.1.2 5.1.3 5.1.4 Automatic switching to alternative MS . Criteria for automatic return to normal in the case of automat

20、ic protection Recovery mechanisms for international connections in the SDH VC trail layer . Subnetwork connection recovery mechanisms 6.1.1 6.1.2 Manual protection for subnetwork connections 6.1.3 VC trail recovery mechanisms . 6.2.1 VC trail protection . 6.2.2 VC trail restoration 6.2.3 VC trail re

21、covery times . VC trail restoration during maintenance activities . VC trail restoration exercises . High priority and pre-emptible VC trails . Automatic protection for subnetwork connections . Subnetwork connection recovery times Appendix I . Bibliography Appendix II . Manual restoration using Digi

22、tal Cross-Connect Equipment . Page 1 1 2 5 6 6 6 6 7 7 7 7 7 7 8 8 10 10 12 13 13 13 13 13 14 ITU-T Recommendation M.2102 Maintenance thresholds and procedures for recovery mechanisms (protection and restoration) of international SDH VC trails (paths) and multiplex sections 1 Scope This ITU-T Recomm

23、endation defines maintenance thresholds and procedures for protection and restoration of international SDH VC trails*, multiplex sections and subnetwork connections in case of failure, degradation, maintenance activities (e.g. planned outages). This ITU-T Recommendation deals with protection and res

24、toration including return to the original configuration. The internal protection capabilities of network element hardware are outside the scope of this Recommendation. Maintenance thresholds and procedures given in this Recommendation are only used for automatic protection and restoration of VC trai

25、ls, multiplex sections and subnetwork connections. ITU-T Recommendations M.2101 7, M.2110 8 and M.2120 9 apply to international SDH VC trails and multiplex sections, prior to, during and following protection or restoration. 2 References The following ITU-T Recommendations and other references contai

26、n 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; all users of this Recommendation are therefore encouraged to investigate

27、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. ITU-T Recommendation G.783 (1 997), Characteristics of synchronous digital hierarchy (SDH) equipment functional bl

28、ocks. ITU-T Recommendation G.803 (2000), Architectures of transport networks based on the synchronous digital hierarchy (SDH). ITU-T Recommendation G. 805 (2000), Genericfunctional architecture of transport networks. ITU-T Recommendation G.841 (1 998), Types and characteristics of SDH network protec

29、tion architectures. ITU-T Recommendation G. 842 (1 997), Interworking of SDH network protection architectures. CCITT Recommendation M.20 (1 992), Maintenance philosophy for telecommunication networks. ITU-T Recommendation M.2 1 O 1 (2000), Performance limits and objectives for bringing-into- sewice

30、and maintenance of international SDHpaths and multiplex sections. ITU-T Recommendation M.211 O (1 997), Bringing-into-service of international PDH paths, sections and transmission systems and SDHpaths and multiplex sections. ITU-T Recommendation M.2 120 (2000), PDH path, section and transmission sys

31、tem and SDH path and multiplex section fault detection and localization procedures. Throughout this ITU-T Recommendation the terms “trail“ and “trails“ should be understood to read “trail (path)“ and trails (paths) respectively. STDmITU-T RECMN M.2102-ENGL 2000 E 4862571 Ob88910 T58 101 ITU-T Recomm

32、endation M. 21 30 (2000), Operational procedures for the maintenance of the transport network. 3 Terms and definitions This ITU-T Recommendation defines the following terms: 3.1 normal: Original configuration of VC trail, SNC or MS: sometimes referred to as “working trail“ or “in-service trail.“ 3.2

33、 alternative trail: Transmission capacity available for recovery purposes. 3.3 switching: The action of transferring transmission capacity between the normal and alternative trail, and vice-versa, using NE switching matrices. 3.4 re-routing: The actions required to divert VC trails or Multiplex Sect

34、ions onto reserved transport network capacity, in the event of working trail failure or degradation. 3.5 acceptable state: Implies the trail is not degraded. See ITU-T Recommendation M.20 6. 3.6 patching: The action of transferring transmission capacity manually between the normal and alternative tr

35、ail, and vice-versa. 3.7 recovery mechanism: A mechanism by which transmission capacity can be recovered after a network failure or degradation. A recovery mechanism is defined by its actions, which are recovery initiation(s) and return(s) to the original configuration. There are two types of recove

36、ry mechanisms: protection and restoration. Descriptions of recovery mechanisms are illustrated in Table 1 and Figure 1. 3.8 recovery initiation: The action which triggers the recovery mechanism. Each recovery mechanism has one or more possible recovery initiations. Examples of NE functions associate

37、d with recovery mechanism actions are: manual switching to the alternative trail which can be achieved using the G.783 i NE function “Manual Switch“ and automatic switching to the alternative trail can be achieved using the G.783 i NE function “APS“. 3.9 return to original configuration: The action

38、which reverses network changes due to a recovery initiation. Each recovery mechanism has one or more possible returns to original configuration. 3.10 automatic protection (revertive): Recovery is initiated by automatic switching to the alternative trail; return to the original configuration is also

39、automatic. The NE normally autonomously provides this functionality; the definitions from the NE perspective are given in ITU-T Recommendation G.783 i. Note that if a manual or forced switching to normal is provided to return to the original configuration, then the particular recovery mechanism is n

40、ot considered to be automatic protection (revertive) for that particular action. 3.1 1 automatic protection (non-revertive): Recovery is initiated by automatic switching to the alternative trail; return to original configuration is done by forced or manual switching to normal. 3.12 manual protection

41、: Recovery is initiated by forced or manual switching to the alternative trail; return to original configuration is done by forced or manual switching to normal. 3.13 automatic restoration (revertive): Recovery is initiated by automatic OS controlled switching to the altemative trail; return to orig

42、inal configuration is done by both automatic OS controlled switching to normal or manual switch to normal. STD.1TU-T RECflN fl.2102-ENGL ZOO0 48b259L Ob88911 994 = 3.14 automatic restoration (non-revertive): Recovery is initiated by automatic OS controlled switching to the alternative trail; return

43、to original configuration is done by manual switching. 3.15 manual restoration: Recovery is initiated by manual patching or manual switching to the alternative trail; return to original configuration is done by manual patching, manual switching or forced switching. 111 486259L 0688932 820 STD-ITU-T

44、RECMN N-2102-ENGL 2000 O - X X - - X X - X X - N O I RECOVERY MECHANISMS/ 1 PROTECTION I 1 Manual 1 Forced switching to alternative trail Manual switching to alternative trail Automatic protection revertive Automatic protection non-revertiv Manual patching to altemative trail I Manual switching to a

45、lternative trail I I Automatic I Automatic restoration Automatic restoration non-revertive To41 1360-99 Figure 1M.2102 - Recovery mechanism overview 4 Abbreviations This ITU-T Recommendation uses the following abbreviations: APS ES HOPM MS MSSPFUNG NE os SD SDH SES Automatic Protection Switching Err

46、ored Second Higher order Path Overhead Monitor Multiplex Section Multiplex Section Shared Protection Ring Network Element Operations System Signal Degrade Synchronous Digital Hierarchy Severely Errored Second STD-ITU-T RECIA 1-2L02-ENGL 2000 II 4862591 0688944 bT3 SF Signal Fail SNC Sub-Network Conn

47、ection UAS UnAvailable Second vc Virtual Container WTR Wait To Restore 5 This clause deals with recovery mechanisms for international SDH multiplex sections. See clause 6 concerning recovery mechanisms for SDH VC trails. Recovery mechanisms for international multiplex sections 5.1 Multiplex section

48、protection 5.1.1 For automatic protection, there are two criteria, SD and SF, as defined in ITU-T Recommendation G.783 i. Network operators are responsible for bi- or multilateral agreement on the SD criterion per intemational multiplex section. Automatic switching to alternative MS 5.1.2 For mainte

49、nance activities, e.g. planned outages, operators may have to force switch the normal MS to the alternative MS (to ensure transmission continuity). It is recommended to use this procedure as a last resort only, due to the fact that a MS protection group3 may carry several normal MSs, and in this case, the alternative MS will not be available for automatic protection (see Figure 2). Forced switching to alternative MS r Forced switching to altemative MS Y TO41 1370-99 Figure 2M.2102 - Forced switching to alternative MS for maintenance a