1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T G.841TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Corrigendum 1(08/2002) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital networks SDH network characteristics Types and characteristics of SDH network protection architectur
2、es Corrigendum 1 ITU-T Recommendation G.841 (1998) Corrigendum 1 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-TRANSMISSION SYSTEMS G.200G.
3、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 RADIOTELEPHONY AND LINE TELEP
4、HONY G.450G.499 TESTING EQUIPMENTS G.500G.599 TRANSMISSION MEDIA CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 General aspects G.800G.809 Design objectives for digital networks G.810G.819 Quality and availability targets G.820G.829 Network capabilities
5、 and functions G.830G.839 SDH network characteristics G.840G.849 Management of transport network G.850G.859 SDH radio and satellite systems integration G.860G.869 Optical transport networks G.870G.879 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 QUALITY OF SERVICE AND PERFORMANCE G.1000G.1999
6、 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DIGITAL TERMINAL EQUIPMENTS G.7000G.7999 DIGITAL NETWORKS G.8000G.8999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. G.841 (1998)/Cor.1 (08/2002) i ITU-T Recommendation G.841 Types and characteristics of SDH networ
7、k protection architectures Corrigendum 1 Source Corrigendum 1 to ITU-T Recommendation G.841 (1998) was prepared by ITU-T Study Group 15 (2001-2004) and approved under the WTSA Resolution 1 procedure on 16 August 2002. ii ITU-T Rec. G.841 (1998)/Cor.1 (08/2002) FOREWORD The International Telecommunic
8、ation 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 Recommendations on them with a
9、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 these topics. The approval of ITU-T Recommen
10、dations 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 expression “Administration“ is used for conci
11、seness 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. ITU takes no posi
12、tion 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 received notice of intellectual property, protected
13、 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. ITU 2002 All rights reserved. No part of this publication may be reproduced
14、, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. G.841 (1998)/Cor.1 (08/2002) iii CONTENTS Page 1 Introduction 1 2 Corrections to Table 7-4 . 1 3 Note to clause 7.2.4.2 paragraph 3 . 3 4 Text replacing part of 7.1.2.1 . 3 5 Correction to Table B.1 4 6 Editorial chan
15、ges to Table B.5 . 4 ITU-T Rec. G.841 (1998)/Cor.1 (08/2002) 1 ITU-T Recommendation G.841 Types and characteristics of SDH network protection architectures Corrigendum 1 1 Introduction This corrigendum contains editorial and technical corrections to the 1998 revision of ITU-T Rec. G.841. 2 Correctio
16、ns to Table 7-4 Changes to Table 7-4 are indicated by revision marks. Table 7-4/G.841 1:n bidirectional protection switching without extra traffic example APS bytes C A A C Action Failure condition or controller state byte K1 byte K2 byte K1 byte K2 at C at A No failures (protection section not in u
17、se) 0000 0000 0000 1000 0000 0000 0000 1000 Null signal is bridged to protection. Selector is released. Null signal is bridged to protection. Selector is released. Working section 2 degraded in direction A C 1010 0010 0000 1000 0000 0000 0000 1000 Failure detected. Request normal traffic signal 2 br
18、idge SD. 1010 0010 0000 1000 0010 0010 0010 1000 Bridge normal traffic signal 2. Reverse request normal traffic signal 2 bridge. 1010 0010 0010 1000 0010 0010 0010 1000 Switch normal traffic signal 2 from protection section. Bridge normal traffic signal 2 to protection. 1010 0010 0010 1000 0010 0010
19、 0010 1000 Switch normal traffic signal 2 from protection. Bidirectional switch completed. 2 ITU-T Rec. G.841 (1998)/Cor.1 (08/2002) Table 7-4/G.841 1:n bidirectional protection switching without extra traffic example APS bytes C A A C Action Failure condition or controller state byte K1 byte K2 byt
20、e K1 byte K2 at C at A Working section 1 failed in direction C A 1010 0010 0010 1000 1100 0001 0000 1000 Failure detected. Request normal traffic signal 1 bridge SF. Release normal traffic signal 2 switch and bridge. (This pre-empts the normal traffic signal 2 switch) 0010 0001 0001 1000 1100 0001 0
21、010 1000 0000 1000 Bridge normal traffic signal 1 to protection. Reverse request normal traffic signal 1 bridge. Release normal traffic signal 2 switch. 0010 0001 0001 1000 1100 0001 0001 1000 Switch normal traffic signal 1. Bridge normal traffic signal 1. 0010 0001 0001 1000 1100 0001 0001 1000 Swi
22、tch normal traffic signal 1. Bidirectional switch completed. Working section 1 repaired 0010 0001 0001 1000 0110 0001 0001 1000 Wait to restore. (Working section 2 still degraded) 1010 0010 0001 1000 0000 1000 0110 0001 0001 1000 Request normal traffic signal 2 bridge. Release normal traffic signal
23、1 switch and bridge. 1010 0010 0001 1000 0000 1000 0010 0010 0010 1000 Bridge normal traffic signal 2. Reverse request normal traffic signal 2 bridge. Release normal traffic signal 1 switch. 1010 0010 0010 1000 0010 0010 0010 1000 Bridge normal traffic signal 2. Switch normal traffic signal 2. ITU-T
24、 Rec. G.841 (1998)/Cor.1 (08/2002) 3 Table 7-4/G.841 1:n bidirectional protection switching without extra traffic example APS bytes C A A C Action Failure condition or controller state byte K1 byte K2 byte K1 byte K2 at C at A Working section 1 repaired (Working section 2 still degraded) 1010 0010 0
25、010 1000 0010 0010 0010 1000 Switch normal traffic signal 2. Bidirectional switch completed. Working section 2 repaired 0110 0010 0010 1000 0010 0010 0010 1000 Wait to restore normal traffic signal 2. 0000 0000 0010 1000 0010 0010 0010 1000 Drop normal traffic signal 2 bridge order. Release normal t
26、raffic signal 2 switch. 0000 0000 0010 1000 0000 0000 0000 1000 Drop normal traffic signal 2 bridge Drop. Drop normal traffic signal 2 bridge request. Release normal traffic signal 2 switch. Wait to restore expired (no failures) 0000 0000 0000 1000 0000 0000 0000 1000 Drop normal traffic signal 2 br
27、idge. Null signal is bridged to protection. Null signal is bridged to protection. 3 Note to clause 7.2.4.2 paragraph 3 A Note is added in clause 7.2.4.2, after paragraph 3: NOTE There is an issue with interworking the protection scheme with WDM systems. The issue occurs when four-fibre spring traffi
28、c is carried over a WDM system and, depending upon the order of repair of a failed WDM link, it may cause the protection scheme to “flap“ between worker and protection. This issue is currently under study. 4 Text replacing part of 7.1.2.1 The manual switch null signal should no longer be used for 1:
29、n protection without extra traffic. The second paragraph of item 4) in clause 7.1.2.1 should be revised as follows: For 1 + 1 systems or 1:n systems without extra traffic, manual switch null signal transfers the working section back from protection to the working section, unless an equal or higher p
30、riority request is in effect. Since manual switch has lower priority than SF or SD on a working section, this command will be carried out only if the working section is not in SF or SD condition. “Manual 4 ITU-T Rec. G.841 (1998)/Cor.1 (08/2002) Switch Null Signal“ has higher priority than “Manual S
31、witch Normal Traffic Signal 1“ when both commands are detected at the same time. 5 Correction to Table B.1 Note 2 to Table B.1 is revised as follows: NOTE 2 In the case of Signal Degrade (SD) on both working sections, no protection switching should take place. Depending on the order in time of the i
32、ndividual SD, the selectors may be switch to section 1 or section 2. In any case, no switching should take place. 6 Editorial changes to Table B.5 Changes to Table B.5 are indicated by removing underlining revision marks. Table B.5/G.841 Example of 1 + 1 bidirectional switching optimized for a netwo
33、rk using predominantly 1 + 1 bidirectional switching Forced Switch from Working Section 2 APS bytes C A A C Action Failure condition or controller state byte K1 byte K2 byte K1 byte K2 at C at A No fault condition traffic on channel 2 0000 0000 0010 0000 0000 0000 0010 0000 Forced Switch from sectio
34、n 2 at side C 1110 0010 0010 0000 0000 0000 0010 0000 Detect local request. Update K1. 1110 0010 0010 0000 0010 0010 0010 0000 Detect remote request. Switch to channel 2 from channel 2 (to channel 1). Issue Reverse Request. 1110 0010 0010 0000 0010 0010 0010 0000 Detect reverse request. Switch from
35、channel 2 (to channel 1).to channel 2. Clear Forced Switch at side C 0000 0000 0001 0000 0010 0010 0010 0000 Send no request. Update K1, K2. No Switch active. Traffic on section 1 0000 0000 0001 0000 0000 0000 0001 0000 Send no request. Update K1, K2. Printed in Switzerland Geneva, 2002 SERIES OF IT
36、U-T RECOMMENDATIONS Series A Organization of the work of ITU-T Series B Means of expression: definitions, symbols, classification Series C General telecommunication statistics Series D General tariff principles Series E Overall network operation, telephone service, service operation and human factor
37、s Series F Non-telephone telecommunication services Series G Transmission systems and media, digital systems and networks Series H Audiovisual and multimedia systems Series I Integrated services digital network Series J Cable networks and transmission of television, sound programme and other multime
38、dia signals Series K Protection against interference Series L Construction, installation and protection of cables and other elements of outside plant Series M TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits Series N Maint
39、enance: international sound programme and television transmission circuits Series O Specifications of measuring equipment Series P Telephone transmission quality, telephone installations, local line networks Series Q Switching and signalling Series R Telegraph transmission Series S Telegraph service
40、s terminal equipment Series T Terminals for telematic services Series U Telegraph switching Series V Data communication over the telephone network Series X Data networks and open system communications Series Y Global information infrastructure and Internet protocol aspects Series Z Languages and general software aspects for telecommunication systems
