1、 International Telecommunication Union ITU-T G.8031/Y.1342TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (06/2011) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Packet over Transport aspects Ethernet over Transport aspects SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERN
2、ET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Internet protocol aspects Transport Ethernet linear protection switching Recommendation ITU-T G.8031/Y.1342 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.
3、100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION 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
4、INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATION OF RADIOTELEPHONY 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 MULTIME
5、DIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS 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.8099MPLS over Transport aspects G.8
6、100G.8199 Quality and availability targets G.8200G.8299 Service Management G.8600G.8699 ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.8031/Y.1342 (06/2011) i Recommendation ITU-T G.8031/Y.1342 Ethernet linear protection switching Su
7、mmary Recommendation ITU-T G.8031/Y.1342 describes the specifics of linear protection switching for Ethernet VLAN signals. Included are details pertaining to ETH linear protection characteristics, architectures, and the APS protocol. The protection scheme considered in this Recommendation is: VLAN-b
8、ased Ethernet subnetwork connection linear protection with sublayer monitoring. History Edition Recommendation Approval Study Group 1.0 ITU-T G.8031/Y.1342 2006-06-06 15 1.1 ITU-T G.8031/Y.1342 (2006) Amd. 1 2007-10-07 15 1.2 ITU-T G.8031/Y.1342 (2006) Cor. 1 2008-06-06 15 2.0 ITU-T G.8031/Y.1342 20
9、09-11-13 15 2.1 ITU-T G.8031/Y.1342 (2009) Cor. 1 2010-09-06 15 3.0 ITU-T G.8031/Y.1342 2011-06-22 15 ii Rec. ITU-T G.8031/Y.1342 (06/2011) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communicat
10、ion 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 worldwide basis. The Wor
11、ld 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 WTSA Resolution 1. In
12、 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 administration and a recog
13、nized 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 provisions are met. The w
14、ords “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 the possibility th
15、at 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 outside of the Recommenda
16、tion development process. As of the date of approval of this Recommendation, ITU had 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 latest information and are
17、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.8031/Y.1342 (06/2011) iii Table of Contents Pag
18、e 1 Scope 1 2 References. 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 4 4 Abbreviations and acronyms 4 5 Conventions 6 5.1 Representation of octets . 6 6 Introduction 6 7 Network objectives . 6 8 Protection characteristics 7 8.1 Monitoring methods and c
19、onditions . 7 9 Protection group commands . 8 9.1 End-to-end commands and states . 8 9.2 Local commands . 9 10 Protection architectures 9 10.1 Unidirectional and bidirectional switching 9 10.2 Need for APS communication 9 10.3 Revertive and non-revertive switching . 10 10.4 Provisioning mismatches 1
20、0 10.5 Protection switching trigger . 10 10.6 Protection switching models . 11 11 APS protocol . 18 11.1 APS format . 18 11.2 1-phase APS protocol . 19 11.3 Request type . 22 11.4 Protection types and bridge type 23 11.5 Requested signal . 23 11.6 Bridged signal . 23 11.7 Control of bridge 24 11.8 C
21、ontrol of selector 24 11.9 Signal fail of the protection transport entity . 24 11.10 Equal priority requests 24 11.11 Command acceptance and retention . 24 11.12 Hold-off timer . 25 11.13 Wait-to-restore timer 25 11.14 Exercise operation 26 iv Rec. ITU-T G.8031/Y.1342 (06/2011) Page 11.15 Failure of
22、 protocol defects 26 11.16 Signal degrade of the protection transport entity . 26 Annex A State transition tables of protection switching. 27 A.1 State transition for 1:1 bidirectional switching with revertive mode . 28 A.2 State transition for 1:1 bidirectional switching with non-revertive mode 32
23、A.3 State transition for 1+1 bidirectional switching with revertive mode 36 A.4 State transition for 1+1 bidirectional switching with non-revertive mode . 39 A.5 State transition for 1+1 unidirectional switching with revertive mode 44 A.6 State transition for 1+1 unidirectional switching with non-re
24、vertive mode . 46 Appendix I Example of operation of 1-phase APS protocol 49 I.1 Introduction 49 I.2 Example scenario 49 I.3 Examples of APS protocol . 49 Appendix II Interaction between Ethernet protection switching and spanning-tree protocol (STP) 52 Appendix III Maintenance entity group intermedi
25、ate points for a protection switching environment 54 III.1 Introduction 54 III.2 Considerations 54 III.3 Examples of configuration . 55 Appendix IV State transition diagrams using specification and description language . 57 IV.1 Introduction 57 IV.2 SDL diagrams . 57 Rec. ITU-T G.8031/Y.1342 (06/201
26、1) 1 Recommendation ITU-T G.8031/Y.1342 Ethernet linear protection switching 1 Scope This Recommendation defines the APS protocol and linear protection switching mechanisms for point-to-point VLAN-based ETH subnetwork connection (SNC) in Ethernet transport networks. All other protection schemes, inc
27、luding point-to-multipoint and multipoint-to-multipoint, are for further study. Linear 1+1 and 1:1 protection switching architectures with unidirectional and bidirectional switching are defined in this version of the Recommendation. The APS protocol and protection switching operation for all other E
28、thernet network architectures, (for example, ring, mesh, etc.), are for further study. 2 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 edition
29、s 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 Recommendations and other references listed below. A list of the currently valid I
30、TU-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 G.780 Recommendation ITU-T G.780/Y.1351 (2008), Terms and definitions for synchronous digital hierarchy (SDH) network
31、s. ITU-T G.805 Recommendation ITU-T G.805 (2000), Generic functional architecture of transport networks. ITU-T G.806 Recommendation ITU-T G.806 (2009), Characteristics of transport equipment Description methodology and generic functionality. ITU-T G.808.1 Recommendation ITU-T G.808.1 (2006), Generic
32、 protection switching Linear trail and subnetwork protection. ITU-T G.841 Recommendation ITU-T G.841 (1998), Types and characteristics of SDH network protection architectures. ITU-T G.870 Recommendation ITU-T G.870/Y.1352 (2008), Terms and definitions for optical transport networks (OTN). ITU-T G.80
33、10 Recommendation ITU-T G.8010/Y.1306 (2004), Architecture of Ethernet layer networks. ITU-T G.8021 Recommendation ITU-T G.8021/Y.1341 (2007), Characteristics of Ethernet transport network equipment functional blocks. ITU-T M.495 Recommendation ITU-T M.495 (1988), Transmission restoration and transm
34、ission route diversity: Terminology and general principles. ITU-T Y.1731 Recommendation ITU-T Y.1731 (2008), OAM functions and mechanisms for Ethernet based networks. IEEE 802 IEEE Std 802-2001, IEEE Standard for Local and Metropolitan Area Networks: Overview and Architecture. 2 Rec. ITU-T G.8031/Y.
35、1342 (06/2011) IEEE 802.1D IEEE Std 802.1D-2004, IEEE Standard for Local and Metropolitan Area Networks: Media Access Control (MAC) Bridges. IEEE 802.1Q IEEE Std 802.1Q-2005, IEEE Standard for Local and Metropolitan Area Networks: Virtual Bridged Local Area Networks. 3 Definitions 3.1 Terms defined
36、elsewhere This Recommendation uses the following terms defined elsewhere: Terms defined in ITU-T G.780: 3.1.1 bidirectional protection switching 3.1.2 unidirectional protection switching Terms defined in ITU-T G.805: 3.1.3 adapted information 3.1.4 characteristic information 3.1.5 link 3.1.6 link co
37、nnection 3.1.7 tandem connection 3.1.8 trail 3.1.9 trail termination Terms defined in ITU-T G.806: 3.1.10 atomic function 3.1.11 defect 3.1.12 failure 3.1.13 server signal degrade (SSD) 3.1.14 server signal fail (SSF) 3.1.15 signal degrade (SD) 3.1.16 signal fail (SF) 3.1.17 trail signal degrade (TS
38、D) 3.1.18 trail signal fail (TSF) Terms defined in ITU-T G.870: 3.1.19 APS protocol 3.1.19.1 1-phase 3.1.20 protection class 3.1.20.1 individual 3.1.20.2 group 3.1.20.3 network connection protection 3.1.20.4 subnetwork connection protection Rec. ITU-T G.8031/Y.1342 (06/2011) 3 3.1.20.4.1 sublayer mo
39、nitored (/S) 3.1.20.4.2 non-intrusive monitored 3.1.20.4.3 inherent monitored 3.1.20.4.4 test monitored (/T) 3.1.20.5 trail protection 3.1.21 switch 3.1.22 component 3.1.22.1 protected domain 3.1.22.2 bridge 3.1.22.2.1 permanent bridge 3.1.22.2.2 broadcast bridge 3.1.22.2.3 selector bridge 3.1.22.3
40、selector 3.1.22.3.1 selective selector 3.1.22.4 head end 3.1.22.5 tail end 3.1.22.6 sink node 3.1.22.7 source node 3.1.22.8 intermediate node 3.1.23 architecture 3.1.23.1 1+1 protection architecture 3.1.23.2 1:n protection architecture 3.1.23.3 (1:1)nprotection architecture 3.1.24 signal 3.1.24.1 tr
41、affic signal 3.1.24.2 normal traffic signal 3.1.24.3 extra traffic signal 3.1.24.4 null signal 3.1.25 time 3.1.25.1 detection time 3.1.25.2 hold-off time 3.1.25.3 wait-to-restore time 3.1.25.24 switching time 3.1.26 transport entity 3.1.26.1 protection transport entity 3.1.26.2 working transport ent
42、ity 3.1.26.3 active transport entity 4 Rec. ITU-T G.8031/Y.1342 (06/2011) 3.1.26.4 standby transport entity 3.1.27 protection 3.1.28 impairment 3.1.29 protection ratio 3.1.30 revertive (protection) operation 3.1.31 non-revertive (protection) operation Terms defined in ITU-T G.8010: 3.1.32 Ethernet c
43、haracteristic information (ETH_CI) 3.1.33 Ethernet flow point (ETH_FP) 3.1.34 maintenance entity 3.1.35 maintenance entity group 3.1.36 maintenance entity group end point (MEP) 3.1.37 maintenance entity group level Term defined in ITU-T G.8021: 3.1.38 Ethernet flow forwarding function (ETH_FF) Term
44、defined in ITU-T M.495: 3.1.39 transfer time (Tt) 3.2 Terms defined in this Recommendation None. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: AI Adapted Information APS Automatic Protection Switching CCM Continuity Check Message CI Characteristic In
45、formation DNR Do Not Revert EC Ethernet Connection ETH Ethernet layer network ETH-AIS Ethernet Alarm Indication Signal function ETH-APS Ethernet Automatic Protection Switching function ETH-CC Ethernet Continuity Check function ETH_CI Ethernet Characteristic Information ETH_FF Ethernet Flow Forwardin
46、g Function ETH_FP Ethernet Flow Point EXER Exercise FS Forced Switch Rec. ITU-T G.8031/Y.1342 (06/2011) 5 FT Flow Termination LCK Locked LO Lockout of protection LOC Loss of Continuity LSB Least Significant Bit MEP Maintenance Entity Group End Point MI Management Information MIP Maintenance Entity G
47、roup Intermediate Point MS Manual Switch MSB Most Significant Bit NR No Request OAM Operation, Administration and Maintenance PDU Protocol Data Unit PS Protection Switching RR Reverse Request RSTP Rapid Spanning-Tree Protocol SD Signal Degrade SDL Specification and Description Language SF Signal Fai
48、l SF-P Signal Fail on Protection SNC SubNetwork Connection SNC/I SubNetwork Connection with Inherent monitoring SNC/N SubNetwork Connection protection with Non-intrusive monitoring SNC/S SubNetwork Connection protection with Sublayer monitoring SNC/T SubNetwork Connection protection with Test-trail
49、monitoring SSD Server Signal Degrade SSF Server Signal Fail STP Spanning-Tree Protocol TCM Tandem Connection Monitoring TSD Trail Signal Degrade TSF Trail Signal Fail Tt Transfer time VID VLAN Identifier VLAN Virtual Local Area Network WTR Wait-To-Restore 6 Rec. ITU-T G.8031/Y.1342 (06/2011) 5 Conventions 5.1 Representation of octets Octets are represented as defined in IEEE 802.1D. When consecutive octets are used to represent a binary number, the lower octet number has the
