1、 International Telecommunication Union ITU-T G.8131/Y.1382TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (07/2014) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Packet over Transport aspects MPLS over Transport aspects SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET P
2、ROTOCOL ASPECTS AND NEXT-GENERATION NETWORKS Internet protocol aspects Transport Linear protection switching for MPLS transport profile Recommendation ITU-T G.8131/Y.1382 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS A
3、ND 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 RADIO-RELAY OR SATELL
4、ITE 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 LINE SYSTEM G.90
5、0G.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 MPLS over Transp
6、ort aspects G.8100G.8199Synchronization, 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.8131/Y.1382 (07/2014) i Recommendation ITU-T G.8131/Y.1382 Linear p
7、rotection switching for MPLS transport profile Summary Recommendation ITU-T G.8131/Y.1382 provides architecture and mechanisms for subnetwork connection (SNC) protection switching for MPLS transport profile (MPLS-TP) networks. It describes the SNC protection architectures type, the uni- and bidirect
8、ional switching types and the revertive/non-revertive operation types. It defines an automatic protection coordination protocol used to coordinate both ends of the protected domain. History Edition Recommendation Approval Study Group Unique ID*1.0 ITU-T G.8131/Y.1382 2007-02-06 15 11.1002/1000/9008
9、1.1 ITU-T G.8131/Y.1382 (2007) Amd. 1 2007-09-22 15 11.1002/1000/9179 2.0 ITU-T G.8131/Y.1382 2014-07-07 15 11.1002/1000/12188Keywords APC, APS, PSC, bridge, selector, SNC protection, MPLS-TP. _ *To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browse
10、r, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/ 11830-en. ii Rec. ITU-T G.8131/Y.1382 (07/2014) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communic
11、ation 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 W
12、orld 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.
13、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 administration and a rec
14、ognized 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
15、 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 the possibility
16、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 outside of the Recommen
17、dation 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 ar
18、e therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2014 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.8131/Y.1382 (07/2014) iii Table of Contents P
19、age 1 Scope 1 2 References. 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 3 4 Abbreviations and acronyms 3 5 Conventions 4 6 Protection architecture and characteristics . 4 6.1 MPLS-TP SNC protection 4 6.2 Switching types 5 6.3 Operation types . 5 6.4 Pro
20、tection switching trigger mechanism 6 6.5 Provisioning mismatches 6 7 Protection group commands and state 7 7.1 End-to-end commands 7 7.2 Local commands . 7 7.3 States . 7 8 Automatic protection coordination protocol . 8 8.1 Automatic protection coordination specific information structure 8 8.2 Prio
21、rities of local and remote requests . 11 8.3 APC initiation criteria . 12 8.4 APC protocol type 12 8.5 Transmission and acceptance of APC messages 13 8.6 1-phase APC protocol . 13 8.7 Equal priority requests 15 8.8 Control of bridge 16 8.9 Control of selector 16 8.10 Acceptance and retention of loca
22、l requests 16 8.11 Hold-off timer . 17 8.12 Wait-to-restore timer 17 8.13 Exercise operation 17 8.14 Signal degrade processing 17 8.15 Failure of protocol defects 18 9 Application architectures 18 9.1 Unidirectional 1+1 SNC/S protection switching 18 9.2 Bidirectional 1+1 SNC/S protection switching 2
23、0 9.3 Bidirectional 1:1 SNC/S protection switching . 21 9.4 Relationship with ITU-T G.8131 (2007) 23 iv Rec. ITU-T G.8131/Y.1382 (07/2014) Page 10 Security aspects 24 Annex A State transition tables of protection switching. 25 Appendix I Operation example of MPLS-TP linear protection protocol 26 Rec
24、. ITU-T G.8131/Y.1382 (07/2014) 1 Recommendation ITU-T G.8131/Y.1382 Linear protection switching for MPLS transport profile 1 Scope This Recommendation provides architecture and mechanisms for linear protection switching for MPLS transport profile (MPLS-TP) networks. The automatic protection coordin
25、ation protocol, and 1+1 and 1:1 protection architecture are defined in this Recommendation. Other protection architecture types are for further study. This Recommendation describes the protection switching functionality for point-to-point connections using the automatic protection switching (APS) mo
26、de defined in IETF RFC 7271. This Recommendation provides a representation of the MPLS-TP technology using the methodologies that have been used for other transport technologies (e.g., synchronous digital hierarchy (SDH), optical transport network (OTN) and Ethernet).12 References The following ITU-
27、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 Recommendation
28、 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 give it,
29、as a stand-alone document, the status of a Recommendation. ITU-T G.780 Recommendation ITU-T G.780/Y.1351 (2010), Terms and definitions for synchronous digital hierarchy (SDH) networks. ITU-T G.805 Recommendation ITU-T G.805 (2000), Generic functional architecture of transport networks. ITU-T G.806 R
30、ecommendation 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 protection switching Linear trail and subnetwork protection. ITU-T G.870 Recommendation ITU-T G.870/Y.1352 (2012), Te
31、rms and definitions for optical transport networks. ITU-T G.8031 Recommendation ITU-T G.8031/Y.1342 (2011), Ethernet linear protection switching. ITU-T G.8110.1 Recommendation ITU-T G.8110.1/Y.1370.1 (2011), Architecture of the Multi-Protocol Label Switching transport profile layer network. ITU-T G.
32、8121 Recommendation ITU-T G.8121/Y.1381 (2013), Characteristics of MPLS-TP equipment functional blocks. IETF RFC 5586 IETF RFC 5586 (2009), MPLS Generic Associated Channel _ 1This ITU-T Recommendation is intended to be aligned with the IETF MPLS RFCs normatively referenced by this Recommendation. 2
33、Rec. ITU-T G.8131/Y.1382 (07/2014) IETF RFC 6378 IETF RFC 6378 (2011), MPLS Transport Profile (MPLS-TP) Linear Protection. IETF RFC 7271 IETF RFC 7271 (2014), MPLS Transport Profile (MPLS-TP) Linear Protection to Match the Operational Expectations of Synchronous Digital Hierarchy, Optical Transport
34、Network, and Ethernet Transport Network Operators. 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 1+1 protection architecture ITU-T G.870 3.1.2 1:n protection architecture ITU-T G.870 3.1.3 1-phase ITU-T G.870 3.1.4 2-phase ITU-T G.870
35、 3.1.5 3-phase ITU-T G.870 3.1.6 active transport entity ITU-T G.870 3.1.7 APS protocol ITU-T G.870 3.1.8 architecture ITU-T G.870 3.1.9 bidirectional protection switching ITU-T G.780 3.1.10 bridge ITU-T G.870 3.1.11 defect ITU-T G.806 3.1.12 failure ITU-T G.806 3.1.13 forced switch ITU-T G.870 3.1.
36、14 hold-off time ITU-T G.870 3.1.15 manual switch ITU-T G.870 3.1.16 non-revertive (protection) operation ITU-T G.870 3.1.17 normal traffic signal ITU-T G.870 3.1.18 permanent bridge ITU-T G.870 3.1.19 protected domain ITU-T G.870 3.1.20 protection ITU-T G.870 3.1.21 protection group ITU-T G.870 3.1
37、.22 protection transport entity ITU-T G.870 3.1.23 revertive (protection) operation ITU-T G.870 3.1.24 selector ITU-T G.870 3.1.25 selector bridge ITU-T G.870 3.1.26 signal ITU-T G.870 3.1.27 signal degrade (SD) ITU-T G.806 3.1.28 signal fail (SF) ITU-T G.806 Rec. ITU-T G.8131/Y.1382 (07/2014) 3 3.1
38、.29 standby transport entity ITU-T G.870 3.1.30 subnetwork connection protection ITU-T G.870 3.1.31 switch ITU-T G.870 3.1.32 traffic signal ITU-T G.870 3.1.33 trail ITU-T G.805 3.1.34 trail protection ITU-T G.870 3.1.35 transport entities ITU-T G.870 3.1.36 unidirectional protection switching ITU-T
39、 G.780 3.1.37 wait-to-restore time ITU-T G.870 3.1.38 working transport entity ITU-T G.870 3.2 Terms defined in this Recommendation This Recommendation defines the following term: 3.2.1 PSC protocol: A means to coordinate the two ends of the protected domain via the exchange of a single message as d
40、efined in IETF RFC 6378. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: ACH Associated Channel Header APC Automatic Protection Coordination APS Automatic Protection Switching dFOP Failure of Protocol defect DNR Do-not-Revert DPath Data Path EXER Exerc
41、ise FPath Fault Path FS Forced Switch G-ACh Generic Associated Channel LO Lockout of protection LSP Label Switched Path MPLS-TP MPLS Transport Profile MS Manual Switch MS-P Manual Switch to Protection transport entity MS-W Manual Switch to Working transport entity MT_C MPLS-TP Connection MT_CP MPLS-
42、TP Connection Point MT_TT_Sk MPLS-TP Trail Termination Sink NR No Request 4 Rec. ITU-T G.8131/Y.1382 (07/2014) OAM Operations, Administration and Maintenance OC Operator Clear OTN Optical Transport Network PDU Protocol Data Unit PSC Protection State Coordination PT Protection Type RR Reverse Request
43、 SD Signal Degrade SDH Synchronous Digital Hierarchy SD-P Signal Degrade on Protection transport entity SD-W Signal Degrade on Working transport entity SF Signal Fail SF-P Signal Fail on Protection transport entity SF-W Signal Fail on Working transport entity SNC Subnetwork Connection SNCP Subnetwor
44、k Connection Protection SNC/S SNCP with Sublayer monitoring TLV Type Length Value WTR Wait-to-Restore 5 Conventions In this Recommendation, the term automatic protection coordination (APC) protocol is used to describe the means to coordinate the two ends of the protected domain via the exchange of a
45、 single message and represents the protection state coordination (PSC) protocol in automatic protection switching (APS) mode as defined in IETF RFC 7271. This protocol is developed to provide the same operator control and experience of APS protocol by modifying and enhancing the PSC protocol as desc
46、ribed in IETF RFC 6378. 6 Protection architecture and characteristics Protection switching is a fully allocated protection mechanism that can be used on any topology. It is fully allocated in the sense that the route and bandwidth of the protection connection is reserved for a selected working conne
47、ction. To be effective under all possible failures of the working connection however, the protection connection must be known to have complete physical diversity over all common-failure modes. This may not always be possible. Also, this might require the working connection not to follow its shortest
48、 path. The MPLS-TP linear protection switching architecture is subnetwork connection protection with sublayer monitoring (SNC/S) protection as defined in ITU-T G.808.1. MPLS-TP trail protection is also supported but the functional model is for further study. Other types are for further study. 6.1 MP
49、LS-TP SNC protection MPLS-TP subnetwork connection protection (SNCP) is used to protect a section of a connection (e.g., that section where two separate routes are available) within an operators network or multiple Rec. ITU-T G.8131/Y.1382 (07/2014) 5 operators networks. Two independent subnetwork connections exist, which act as working and protection transport entities for the (p
