1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T G.8032/Y.1344 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (08/2015) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Packet over Transport aspects Ethernet over Transport aspects SERIES Y: GLOBAL I
2、NFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Internet protocol aspects Transport Ethernet ring protection switching Recommendation ITU-T G.8032/Y.1344 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPH
3、ONE CONNECTIONS AND CIRCUITS G.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 RADI
4、O-RELAY OR SATELLITE LINKS AND 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
5、 LINE SYSTEM G.900G.999 MULTIMEDIA 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.8099
6、 MPLS over Transport aspects G.8100G.8199 Synchronization, 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.8032/Y.1344 (08/2015) i Recommendation ITU-T G.80
7、32/Y.1344 Ethernet ring protection switching Summary Recommendation ITU-T G.8032/Y.1344 defines the automatic protection switching (APS) protocol and protection switching mechanisms for Ethernet layer network (ETH) ring topologies. Included are details pertaining to Ethernet ring protection characte
8、ristics, architectures and the ring APS (R-APS) protocol. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T G.8032/Y.1344 2008-06-22 15 11.1002/1000/9415 1.1 ITU-T G.8032/Y.1344 (2008) Amd. 1 2009-04-22 15 11.1002/1000/9678 2.0 ITU-T G.8032/Y.1344 2010-03-09 15 11.1002/1000/10
9、661 2.1 ITU-T G.8032/Y.1344 (2010) Amd. 1 2010-06-11 15 11.1002/1000/10934 2.2 ITU-T G.8032/Y.1344 (2010) Cor. 1 2010-10-07 15 11.1002/1000/10902 2.3 ITU-T G.8032/Y.1344 (2010) Amd. 2 2011-02-25 15 11.1002/1000/11328 3.0 ITU-T G.8032/Y.1344 2012-02-13 15 11.1002/1000/11514 3.1 ITU-T G.8032/Y.1344 (2
10、012) Amd. 1 2013-07-12 15 11.1002/1000/12025 4.0 ITU-T G.8032/Y.1344 2015-08-13 15 11.1002/1000/12550 _ * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/10
11、00/11830-en. ii Rec. ITU-T G.8032/Y.1344 (08/2015) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a pe
12、rmanent 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 World Telecommunication Standardization Assembly (WTSA), which meets every four years, estab
13、lishes 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 some areas of information technology which fall within ITU-Ts purview, the necessary sta
14、ndards 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 recognized operating agency. Compliance with this Recommendation is voluntary. However, the Re
15、commendation 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 words “shall“ or some other obligatory language such as “must“ and the negative equivalent
16、s 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 RIGHTSITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed
17、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 Recommendation development process. As of the date of approval of this Recommendation, ITU had recei
18、ved 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 therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr
19、/. ITU 2015 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.8032/Y.1344 (08/2015) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms def
20、ined in this Recommendation . 3 4 Abbreviations and acronyms 3 5 Conventions 4 5.1 Representation of octets . 4 6 Introduction . 5 7 Ring protection characteristics . 5 7.1 Monitoring methods and conditions . 5 7.2 Ethernet traffic and bandwidth consideration . 6 7.3 Ethernet ring protection switchi
21、ng performance 6 8 Ring protection conditions and commands. 6 9 Ring protection architectures 7 9.1 Revertive and non-revertive switching . 7 9.2 Protection switching triggers 7 9.3 Protection switching models on a single Ethernet ring 7 9.4 Traffic channel blocking . 11 9.5 R-APS channel blocking 1
22、1 9.6 Filtering database flush . 12 9.7 Ethernet ring protection switching models for interconnection . 12 10 Protection control protocol . 21 10.1 Principles of operations 21 10.2 Protection switching behaviour 37 10.3 R-APS format . 43 10.4 Failure of protocol defect . 45 Appendix I Ring protectio
23、n network objectives . 46 Appendix II Ethernet ring network objectives 48 Appendix III Ring protection scenarios 50 Appendix IV Considerations for different timers . 59 IV.1 State machine use of timers 59 IV.2 Guard timer use to block outdated R-APS messages . 59 Appendix V 61 Appendix VI . 62 Appen
24、dix VII . 63 Appendix VIII Flush optimization 64 iv Rec. ITU-T G.8032/Y.1344 (08/2015) Page VIII.1 Flushing FDB consideration . 64 VIII.2 Scenarios of unnecessary FDB flushing . 64 VIII.3 Example of FDB flush optimization . 64 VIII.4 Additional definition of the ERP control process model and state m
25、achine 65 VIII.5 DNF status 69 Appendix IX . 70 Appendix X 71 Appendix XI . 72 Bibliography. 73 Rec. ITU-T G.8032/Y.1344 (08/2015) 1 Recommendation ITU-T G.8032/Y.1344 Ethernet ring protection switching 1 Scope This Recommendation defines the automatic protection switching (APS) protocol and protect
26、ion switching mechanisms for Ethernet layer network (ETH) ring topologies. The protection protocol defined in this Recommendation enables protected point-to-point, point-to-multipoint and multipoint-to-multipoint connectivity within a ring or interconnected rings, called “multi-ring/ladder network“
27、topology. The ETH ring maps to the physical layer ring structure. Protection schemes for the other layers, including the Ethernet physical layer network (ETY), are out of the scope of this Recommendation. 2 References The following ITU-T Recommendations and other references contain provisions which,
28、 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 Recommendation are therefore encouraged to investigate the possibility of appl
29、ying 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 give it, as a stand-alone document, the status of a Recommendation. ITU-T
30、 G.805 Recommendation ITU-T G.805 (2000), Generic functional architecture of transport networks. ITU-T G.806 Recommendation ITU-T G.806 (2012), Characteristics of transport equipment Description methodology and generic functionality. ITU-T G.808.1 Recommendation ITU-T G.808.1 (2014), Generic protect
31、ion switching Linear trail and subnetwork protection. ITU-T G.809 Recommendation ITU-T G.809 (2003), Functional architecture of connectionless layer networks. ITU-T G.870 Recommendation ITU-T G.870/Y.1352 (2012), Terms and definitions for optical transport networks (OTN). ITU-T G.8001 Recommendation
32、 ITU-T G.8001/Y.1354 (2013), Terms and definitions for Ethernet frames over transport. ITU-T G.8010 Recommendation ITU-T G.8010/Y.1306 (2004), Architecture of Ethernet layer networks. ITU-T G.8013 Recommendation ITU-T G.8013/Y.1731 (2013), Operation, administration and management (OAM) functions and
33、 mechanisms for Ethernet based networks. ITU-T G.8021 Recommendation ITU-T G.8021/Y.1341 (2015), Characteristics of Ethernet transport network equipment functional blocks. IEEE 802.1Q IEEE Std 802.1Q (2014), IEEE standard for local and metropolitan area networks: Media access control (MAC) bridges a
34、nd virtual bridged local area networks. 2 Rec. ITU-T G.8032/Y.1344 (08/2015) 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 Terms defined in ITU-T G.805: a) adapted information b) characteristic information c) link d) tandem connection
35、 e) trail 3.1.2 Terms defined in ITU-T G.806: a) defect b) failure c) server signal fail (SSF) d) signal degrade (SD) e) signal fail (SF) f) trail signal fail (TSF) 3.1.3 Terms defined in ITU-T G.808.1: a) transfer time (Tt) 3.1.4 Terms defined in ITU-T G.809: a) adaptation b) flow c) layer network
36、d) network e) port f) transport g) transport entity 3.1.5 Terms defined in ITU-T G.870: a) hold-off time b) non-revertive (protection) operation c) protected domain d) protection e) protection transport entity f) revertive (protection) operation g) signal h) switch i) switching time j) wait-to-resto
37、re time k) working transport entity Rec. ITU-T G.8032/Y.1344 (08/2015) 3 3.1.6 Terms defined in ITU-T G.8001: a) ERP instance b) Ethernet ring c) Ethernet ring node d) interconnection node e) maintenance entity (ME) f) maintenance entity group (MEG) g) major ring h) MEG end point (MEP) i) R-APS virt
38、ual channel j) ring MEL k) ring protection link (RPL) l) RPL neighbour node m) RPL owner node n) sub-ring o) sub-ring link p) wait to block timer 3.2 Terms defined in this Recommendation None. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: AI Adapted
39、Information APS Automatic Protection Switching BPR Blocked Port Reference CCM Continuity Check Message CI Characteristic Information DNF Do Not Flush E-LAN Ethernet LAN EPL Ethernet Private Line ERP Ethernet Ring Protection ETH Ethernet layer network ETHDi Ethernet MAC layer network Diagnostic funct
40、ion within MIP ETY Ethernet physical layer network EVPL Ethernet Virtual Private Line FDB Filtering Database FF Flow Forwarding FOP-PM Failure Of Protocol Provisioning Mismatch FOP-TO Failure Of Protocol Time Out 4 Rec. ITU-T G.8032/Y.1344 (08/2015) FP Flow Point FS Forced Switch GFP Generic Framing
41、 Procedure ID Identification MAC Media Access Control MEG Maintenance Entity Group MEL Maintenance Entity group Level MEP Maintenance entity group End Point MI Management Information MPLS Multiprotocol Label Switching MS Manual Switch NR No Request OAM Operation, Administration and Maintenance OUI O
42、rganizationally Unique Identifier PDU Protocol Data Unit R-APS Ring APS RB RPL Blocked RPL Ring Protection Link SD Signal Degrade SDH VC Synchronous Digital Hierarchy Virtual Circuit SF Signal Fail SSF Server Signal Fail STP Spanning Tree Protocol TCM Tandem Connection Monitoring TLV Type, Length an
43、d Value Tx Transmit VID VLAN Identifier VLAN Virtual Local Area Network VPLS Virtual Private Local Area Network Service WTB Wait To Block WTR Wait To Restore 5 Conventions 5.1 Representation of octets Octets are represented as defined in ITU-T G.8013. Rec. ITU-T G.8032/Y.1344 (08/2015) 5 When consec
44、utive octets are used to represent a binary number, the lowest octet number has the most significant value. The bits in an octet are numbered from 1 to 8, where 1 is the least significant bit and 8 is the most significant bit. 6 Introduction This Recommendation specifies protection switching mechani
45、sms and a protocol for Ethernet layer network (ETH) rings. Ethernet rings can provide wide-area multipoint connectivity more economically due to their reduced number of links. The mechanisms and protocol defined in this Recommendation achieve highly reliable and stable protection; and never form loo
46、ps, which would fatally affect network operation and service availability. Each Ethernet ring node is connected to adjacent Ethernet ring nodes participating in the same Ethernet ring, using two independent links. A ring link is bounded by two adjacent Ethernet ring nodes and a port for a ring link
47、is called a ring port. The minimum number of Ethernet ring nodes in an Ethernet ring is two. The fundamentals of this ring protection switching architecture are: a) the principle of loop avoidance; and b) the utilization of learning, forwarding and filtering database (FDB) mechanisms defined in the
48、Ethernet flow forwarding function (ETH_FF ITU-T G.8021). Loop avoidance in an Ethernet ring is achieved by guaranteeing that, at any time, traffic may flow on all but one of the ring links. This particular link is called the ring protection link (RPL) and under normal conditions this ring link is bl
49、ocked, i.e., not used for service traffic. One designated Ethernet ring node, the RPL owner node, is responsible for blocking traffic at one end of the RPL. Under an Ethernet ring failure condition, the RPL owner node is responsible for unblocking its end of the RPL, unless the RPL has failed, allowing the RPL to be used for traffic. The other Ethernet ring node adjacent to the RPL, the RPL neighbour node, may also participate in blocking or unblocking its end of the R
