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 (01/2015) 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 AND NEXT-GENERATION NETWORKS 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-SERIES RECOMMENDATIONS TRANSMISSION
3、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 ON METALLIC LINES G.300G.399 GENERA
4、L 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.600G.699 DIGITAL TERMINAL EQUIPMENTS
5、 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 ASPECTS G.7000G.7999 General G.7000G.709
6、9 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 (01/2015) i Recommendation ITU-T G.7714.1/Y.1705.1 Protocol for automatic disc
7、overy 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 describes the process of discover
8、ing 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 physical media adjacency discover
9、y, transport entity capability exchange, etc., will be addressed in future Recommendations. The 2015 revision to this Recommendation includes: 1) support for transport networks other than synchronous digital hierarchy (SDH) and optical transport network (OTN), specifically Ethernet (ETH); and 2) err
10、ata 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 11.1002/1000/10896 3.0 ITU-T G.7714.1/Y.1705.1 2
11、015-01-13 15 11.1002/1000/12379 Keywords Auto-discovery, automatic switched optical network, automatic switched transport network, layer adjacency discovery, network resources. _ * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by
12、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 (01/2015) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication techno
13、logies (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 World Telecom
14、munication 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 some area
15、s 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 recognized oper
16、ating 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 words “shal
17、l“ 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 RIGHTSITU draws attention to the possibility that the prac
18、tice 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 Recommendation develo
19、pment 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 therefore s
20、trongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. 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.7714.1/Y.1705.1 (01/2015) iii Table of Contents Page 1 Sco
21、pe . 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 relationships determination 5 6 Mechanisms for layer adjacency discovery 5 6.1 Layer adjacency discovery
22、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 messages 11 9.1 LAPD-based mechanism 12 9.2 PPP-based mechanism 12 9.3 Interoperable solution when us
23、ing ECC based mechanism . 12 10 Layer adjacency based on packet OAM frames . 13 10.1 Ethernet link discovery mechanism 13 10.2 MPLS-TP transport entity discovery mechanism . 14 11 Procedures . 14 12 Discovery response message 15 12.1 Miswiring detection 16 12.2 Misconnection detection . 16 Appendix
24、I Implementation example of discovery process 17 I.1 Layer adjacency discovery information flow . 17 Appendix II Miswiring detection 19 II.1 Auto discovery procedures . 19 II.2 Example: Interaction between two DAs using different discovery message formats . 23 Appendix III Example of discovery respo
25、nse message using generalized MPLS-based mechanism 25 Appendix IV Layer adjacency discovery implementation examples 27 Appendix V In-band message encoding example . 28 Appendix VI Usage of the different discovery mechanisms 30 VI.1 Introduction 30 VI.2 Categories of Type 1 layer adjacency discovery
26、use cases 30 iv Rec. ITU-T G.7714.1/Y.1705.1 (01/2015) Page VI.3 Use cases and scenarios 30 VI.4 Guidelines for mechanisms and procedures . 33 Bibliography. 37 Rec. ITU-T G.7714.1/Y.1705.1 (01/2015) 1 Recommendation ITU-T G.7714.1/Y.1705.1 Protocol for automatic discovery in transport networks 1 Sco
27、pe This Recommendation describes the methods, procedures and transport plane mechanisms for discovering layer adjacency according to the requirements of ITU-T G.7714. Layer adjacency discovery (LAD) describes the process of discovering link connection end-point relationships and verifying their conn
28、ectivity. The term “discovery“ is used throughout the Recommendation to refer to both “discovery“ and verification. 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 obtai
29、ning physical media adjacency discovery, transport entity capability exchange, etc., will be addressed in future Recommendations. Equipment developed prior to this Recommendation might not interwork with some of the features developed within this Recommendation. Care should be taken where old and ne
30、w equipments are to interwork. 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 editions indicated were valid. All Recommendations and other re
31、ferences 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 ITU-T Recommendations is regularly published. The referen
32、ce to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. 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 tra
33、nsport networks based on the synchronous digital hierarchy (SDH). 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 transport entities. ITU-
34、T G.8010 Recommendation ITU-T G.8010/Y.1306 (2004), Architecture of Ethernet layer networks. ITU-T G.8080 Recommendation ITU-T G.8080/Y.1304 (2006), Architecture for the automatically switched optical networks (ASON), plus Amendment 2 (2010). ITU-T T.50 Recommendation ITU-T T.50 (1992), Internationa
35、l Reference Alphabet (IRA) (Formerly International Alphabet No. 5 or IA5) Information Technology 7-bit coded character set for information interchange. IEEE 802.1AB IEEE Std 802.1AB (2005), Standard for local and metropolitan area networks Station and Media Access Control Connectivity Discovery. IET
36、F RFC 1570 IETF RFC 1570 (1994), PPP LCP Extentions. 2 Rec. ITU-T G.7714.1/Y.1705.1 (01/2015) IETF RFC 1662 IETF RFC 1662 (1994), PPP in HDLC-like Framing IETF RFC 2045 IETF RFC 2045 (1996), Multipurpose Internet Mail Extentions (MIME) Part One: Format of Internet Message Bodies. 3 Definitions 3.1 T
37、erms 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) subnetwork connection (SNC) e) trail 3.1.2 ITU-T G.8080: a) discovery agent b) policy c) termination adaptation performer 3.1.3 ITU-T G.7714: a) servi
38、ce capability exchange 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 local TCP-ID: An TCP-ID that has local significance to the discovery agent transmitting the discovery messages. 3.2.2 local CP-ID: A CP-ID that has local significance to the discove
39、ry agent transmitting the discovery messages. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: ADM Add-Drop Multiplexer AITS Acknowledged Information Transfer Service API Access Point Identifier ASON Automatically Switched Optical Network CO Central Off
40、ice CP Connection Point DA ID Discovery Agent Identifier DA Discovery Agent. Also known in ITU-T G.7714 as a type of Control Entity DCC Data Communications Channel (ECC in SDH) Rec. ITU-T G.7714.1/Y.1705.1 (01/2015) 3 DCN Data Communications Network DM Discovery Message DXC Digital Cross Connect ECC
41、 Embedded Control Channel (see ITU-T G.7712) ETH Ethernet ETY Ethernet PHY GCC General Communications Channel (ECC in OTN) GMPLS Generalized Multi-Protocol Label Signalling HDLC High-level Data Link Control (in SDH) HOVC Higher Order Virtual Container (in SDH) LAD Layer Adjacency Discovery LAPD Link
42、 Access Procedure D-channel LC Link Connection LCP Link Control Protocol LLCF Link Layer Convergence Function LLDP Link Layer Discovery Protocol LOVC Lower Order Virtual Container (in SDH) LRM Link Resource Manager MAC Media Access Control MS Multiplex Section NE Network Element NMS Network Manageme
43、nt System OAM Operations Administration and Maintenance ODUk Optical Channel Data Unit-k (in OTN) OTN Optical Transport Network OTUk completely standardized Optical Channel Transport Unit-k (in OTN) PC Protocol Controller PM Path Monitoring (in OTN) PPP Point-to-Point Protocol RS Regenerator Section
44、 (in SDH) RSA Regenerator Section Adaptation RST Regenerator Section Termination MS Multiplex Section MSA Multiplex Section Adaptation MST Multiplex Section Adaptation SAPI Source Access Point Identifier SDH Synchronous Digital Hierarchy 4 Rec. ITU-T G.7714.1/Y.1705.1 (01/2015) SM Section Monitoring
45、 (in OTN) SNC Subnetwork Connection TAP Termination and Adaptation Performer TCM Tandem Connection Monitoring TCP Termination Connection Point TCP-ID Termination Connection Point Identifier TLV Type-Length-Value TT Trail Termination TTI Trail Termination Identifier UITS Unacknowledged Information Tr
46、ansfer Service 5 Discovery methodology The discovery methodology uses the processes defined in the following clauses to 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
47、 derived using local information. The following two discovery methods are defined: a) Link discovery process using server 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 use
48、d to carry the discovery message. 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 client signal being carri
49、ed by the link. b) Link discovery process using client layer payload method In this process a signal is injected in the client layer payload to discover the peer TCPs (e.g., TCP1S to TCP1R in Figure 1). The CP-to-CP relationship is inferred from the local knowledge of the matrix connection that was previously set up to connect the test signal to the desired CP (shown in Figure 1). In contrast to the link discovery process using server trail overhead, this appro
