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.7714.1/Y.1705.1 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (08/2017) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Data over Transport Generic aspects Transport network control aspects SERIES
2、 Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS, NEXT-GENERATION NETWORKS, INTERNET OF THINGS AND SMART CITIES Internet protocol aspects Operation, administration and maintenance Protocol for automatic discovery in transport networks Recommendation ITU-T G.7714.1/Y.1705.1 ITU-T G-SE
3、RIES 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.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS O
4、N 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 TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.60
5、0G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL 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 ASPECT
6、S G.7000G.7999 General G.7000G.7099 Transport network control aspects G.7700G.7799 PACKET OVER TRANSPORT ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.7714.1/Y.1705.1 (08/2017) i Recommendation ITU-T G.7714.1/Y.
7、1705.1 Protocol for automatic discovery in transport networks Summary Recommendation ITU-T G.7714.1/Y.1705.1 describes the methods, procedures and transport plane mechanisms for discovering layer adjacency according to the requirements of Recommendation ITU-T G.7714/Y.1705. Layer adjacency discovery
8、 describes the process of discovering link connection end-point relationships and verifying their connectivity. Two alternative methods are described: one using a test set in the client layer, the other using in-band overhead in the server layer. Additional actions that may be required for obtaining
9、 physical media adjacency discovery, transport entity capability exchange, etc., will be addressed in future Recommendations. Recommendation ITU-T G.7714.1/Y.1705.1 (2017) includes: 1) support for transport networks other than synchronous digital hierarchy (SDH) and optical transport network (OTN),
10、specifically Ethernet (ETH); and 2) errata updates. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T G.7714.1/Y.1705.1 2003-04-22 15 11.1002/1000/6291 1.1 ITU-T G.7714.1/Y.1705.1 (2003) Amd. 1 2006-02-17 15 11.1002/1000/8748 2.0 ITU-T G.7714.1/Y.1705.1 2010-09-06 15 11.1002/1
11、000/10896 3.0 ITU-T G.7714.1/Y.1705.1 2015-01-13 15 11.1002/1000/12379 4.0 ITU-T G.7714.1/Y.1705.1 2017-08-13 15 11.1002/1000/13337 Keywords Auto-discovery, automatic switched optical network, automatic switched transport network, layer adjacency discovery, network resources. _ * To access the Recom
12、mendation, 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/11.1002/1000/11830-en. ii Rec. ITU-T G.7714.1/Y.1705.1 (08/2017) FOREWORD The International Telecommunication Union (ITU) is the United
13、 Nations specialized agency in the field of telecommunications, information and communication 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 Recommendat
14、ions on them with a 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 approv
15、al 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 standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administratio
16、n“ is used for conciseness to indicate both a telecommunication administration and a recognized 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
17、 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 equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is req
18、uired 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 Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellec
19、tual 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 by patents, which may be required to implement this Recommendation. Howeve
20、r, 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/. ITU 2017 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prio
21、r written permission of ITU. Rec. ITU-T G.7714.1/Y.1705.1 (08/2017) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 2 3.1 Terms defined elsewhere 2 3.2 Terms defined in this Recommendation . 2 4 Abbreviations and acronyms 2 5 Discovery methodology 4 5.1 CP-CP connectivity relat
22、ionships determination 5 6 Mechanisms for layer adjacency discovery 5 6.1 Layer adjacency discovery of transport entities . 5 7 Attributes used in layer adjacency 6 8 Layer adjacency based on trail trace string . 7 8.1 Discovery message formats 9 9 Layer adjacency based on embedded control channel m
23、essages 11 9.1 LAPD-based mechanism 12 9.2 PPP-based mechanism 12 9.3 Interoperable solution when using ECC based mechanism . 12 9.4 PPP-based support in OTN ECC 13 10 Layer adjacency based on packet OAM frames . 14 10.1 Ethernet link discovery mechanism 14 10.2 MPLS-TP transport entity discovery me
24、chanism . 14 11 Procedures . 15 12 Discovery response message 15 12.1 Miswiring detection 16 12.2 Misconnection detection . 16 Appendix I Implementation example of discovery process 17 I.1 Layer adjacency discovery information flow . 17 Appendix II Miswiring detection 19 II.1 Auto-discovery procedur
25、es . 19 II.2 Example: Interaction between two DAs using different DM formats 23 Appendix III Example of discovery response message using a generalized multi-protocol label signalling-based mechanism 25 Appendix IV Layer adjacency discovery implementation examples 27 Appendix V In-band message encodi
26、ng example . 28 Appendix VI Usage of the different discovery mechanisms 30 VI.1 Introduction 30 VI.2 Categories of Type 1 layer adjacency discovery use cases 30 iv Rec. ITU-T G.7714.1/Y.1705.1 (08/2017) Page VI.3 Use cases and scenarios 30 VI.4 Guidelines for mechanisms and procedures . 33 Bibliogra
27、phy. 37 Rec. ITU-T G.7714.1/Y.1705.1 (08/2017) 1 Recommendation ITU-T G.7714.1/Y.1705.1 Protocol for automatic discovery in transport networks 1 Scope This Recommendation describes the methods, procedures and transport plane mechanisms for discovering layer adjacency according to the requirements of
28、 ITU-T G.7714. Layer adjacency discovery (LAD) describes the process of discovering link connection (LC) end-point relationships and verifying their connectivity. The term “discovery“ is used throughout the Recommendation to refer to both “discovery“ and verification. Two alternative methods are des
29、cribed: one using a test set in the client layer; the other using in-band overhead in the server layer. Additional actions that may be required to obtain physical media adjacency discovery, transport entity capability exchange, etc., will be addressed in future Recommendations. Equipment developed p
30、rior to this Recommendation might not interwork with some of the features developed within this Recommendation. Care should be taken where old and new equipment are to interwork. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this
31、 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 applying the most recent editi
32、on 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 G.709 Recommendation ITU-
33、T G.709/Y.1331 (2016) Interfaces for the optical transport network. ITU-T G.805 Recommendation ITU-T G.805 (2000), Generic functional architecture of transport networks. ITU-T G.831 Recommendation ITU-T G.831 (2000), Management capabilities of transport networks based on the synchronous digital hier
34、archy (SDH). ITU-T G.7701 Recommendation ITU-T G.7701 (2016), Common control aspects. ITU-T G.7712 Recommendation ITU-T G.7712/Y.1703 (2010), Architecture and specification of data communication network. ITU-T G.7714 Recommendation ITU-T G.7714/Y.1705 (2005), Generalized automatic discovery for tran
35、sport entities. ITU-T G.8010 Recommendation ITU-T G.8010/Y.1306 (2004), Architecture of Ethernet layer networks. ITU-T T.50 Recommendation ITU-T T.50 (1992), International Reference Alphabet (IRA) (Formerly International Alphabet No. 5 or IA5) Information technology 7-bit coded character set for inf
36、ormation interchange. IEEE 802.1AB IEEE Std 802.1AB-2016, IEEE Standard for local and metropolitan area networks Station and media access control connectivity discovery. IEEE 802.3 IEEE Std 802.3-2015, Standard for Ethernet. IETF RFC 1570 IETF RFC 1570 (1994), PPP LCP extensions. 2 Rec. ITU-T G.7714
37、.1/Y.1705.1 (08/2017) IETF RFC 1662 IETF RFC 1662 (1994), PPP in HDLC-like framing. IETF RFC 2045 IETF RFC 2045 (1996), Multipurpose internet mail extensions (MIME) Part One: Format of Internet message bodies. IETF RFC 3518 IETF RFC 3518 (2003), Point-to-point protocol (PPP) bridging control protoco
38、l (BCP). 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 ITU-T G.805: a) adaptation b) link c) link connection d) trail 3.1.2 ITU-T G.7701: a) discovery agent b) policy c) termination adaptation performer (TAP) 3.2 Terms defined in this
39、 Recommendation This Recommendation defines the following terms: 3.2.1 local TCP-ID: A termination connection point identifier (TCP-ID) that has local significance to the discovery agent transmitting the discovery messages. 3.2.2 local CP-ID: A connection point identifier (CP-ID) that has local sign
40、ificance to the discovery agent transmitting the discovery messages. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: ADM Add-Drop Multiplexer AIS Alarm Indication Signal AITS Acknowledged Information Transfer Service API Access Point Identifier ASON Au
41、tomatically Switched Optical Network BCP Bridging Control Protocol CO Central Office CP Connection Point CP-ID Connection Point Identifier DA-ID Discovery Agent Identifier DA Discovery Agent Rec. ITU-T G.7714.1/Y.1705.1 (08/2017) 3 DA ID Discovery Agent Identifier DAPI Destination Access Point Ident
42、ifier DCC Data Communications Channel DCN Data Communications Network DM Discovery Message DXC Digital cross Connect ECC Embedded Communication Channel ETH Ethernet ETY Ethernet PHY GCC General Communications Channel GMPLS Generalized Multi-Protocol Label Signalling HDLC High-level Data Link Control
43、 HOVC Higher Order Virtual Container IP Internet Protocol IRV International Reference Version LAD Layer Adjacency Discovery LAPD Link Access Procedure D-channel LC Link Connection LCP Link Control Protocol LL Link Layer LLCF Link Layer Convergence Function LLDP Link Layer Discovery Protocol LOVC Low
44、er Order Virtual Container MAC Media Access Control MIB Management Information Base MPLS Multi-Protocol Label Signalling MS Multiplex Section NE Network Element NMS Network Management System OAM Operations Administration and Maintenance ODUk Optical channel Data Unit-k OTN Optical Transport Network
45、OTUk completely standardized Optical channel Transport Unit-k PC Protocol Controller PDU Protocol Data Unit PM Path Monitoring PPP Point-to-Point Protocol 4 Rec. ITU-T G.7714.1/Y.1705.1 (08/2017) RS Regenerator Section SAPI Source Access Point Identifier SDH Synchronous Digital Hierarchy SM Section
46、Monitoring SNP Subnetwork Point STM Synchronous Transport Module TAP Termination and Adaptation Performer TCE Transport entity Capability Exchange TCM Tandem Connection Monitoring TCP Termination Connection Point TCP-ID Termination Connection Point Identifier TIM Trace Identifier Mismatch TLV Type-L
47、ength-Value TT Trail Termination TTI Trail Trace Identifier UDP User Datagram Protocol UI Unnumbered Information UITS Unacknowledged Information Transfer Service WDM Wavelength Division Multiplexing 5 Discovery methodology The discovery methodology uses the processes specified in clauses 6 to 12 to
48、determine the termination connection point- (TCP)- to-TCP relationship. Once the TCP-to-TCP relationship is determined, the connection point- (CP)- to-CP connectivity relationships are derived using local information. The following two discovery methods are defined. a) Link discovery process using s
49、erver trail overhead method In this process, the server layer trail overhead is used to discover the peer TCPs (e.g., TCP3S to TCP3R in Figure 1). The server layer trail overhead is used to carry the discovery message (DM). The CP-to-CP relationships are inferred from the TCP-to-TCP relationships using local knowledge of the configuration of the adaptation function and its relationship with the trail termination (TT) function. This process does not disrupt the cli
