1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T G.7715.1/Y.1706.1TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (02/2004) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital terminal equipments Operations, administration and maintenance features of transmission equipment SER
2、IES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECTS AND NEXT GENERATION NETWORKS Internet protocol aspects Operation, administration and maintenance ASON routing architecture and requirements for link state protocols ITU-T Recommendation G.7715.1/Y.1706.1 ITU-T G-SERIES RECOMMENDATIO
3、NS 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 ON METALLIC LINES G
4、.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 TESTING EQUIPMENTS G.500G.599 TRANSMISSION MEDIA CHARACTERISTICS G.600G.699 D
5、IGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DIGITAL TERMINAL EQUIPMENTS G.7000G.7999 General G.70
6、00G.7099 Coding of analogue signals by pulse code modulation G.7100G.7199 Coding of analogue signals by methods other than PCM G.7200G.7299 Principal characteristics of primary multiplex equipment G.7300G.7399 Principal characteristics of second order multiplex equipment G.7400G.7499 Principal chara
7、cteristics of higher order multiplex equipment G.7500G.7599 Principal characteristics of transcoder and digital multiplication equipment G.7600G.7699 Operations, administration and maintenance features of transmission equipment G.7700G.7799 Principal characteristics of multiplexing equipment for the
8、 synchronous digital hierarchy G.7800G.7899 Other terminal equipment G.7900G.7999 DIGITAL NETWORKS G.8000G.8999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. G.7715.1/Y.1706.1 (02/2004) i ITU-T Recommendation G.7715.1/Y.1706.1 ASON routing architecture and requir
9、ements for link state protocols Summary This Recommendation provides architecture and requirements for a link-state realization of ITU-T Rec. G.7715/Y.1706. It identifies protocol-neutral requirements for hierarchical link state routing derived from ITU-T Recs G.8080/Y.1304 and G.7715/Y.1706 in a di
10、stributed environment. The distribution of the architectural components is defined in ITU-T Rec. G.8080/Y.1304, and this Recommendation is one realization of the ASON routing architecture. Source ITU-T Recommendation G.7715.1/Y.1706.1 was approved on 22 February 2004 by ITU-T Study Group 15 (2001-20
11、04) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. G.7715.1/Y.1706.1 (02/2004) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent or
12、gan 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, establishes the
13、 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 standards are
14、 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 Recommendati
15、on 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 equivalents are used t
16、o 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 that the practice or implementation of this Recommendation may involve the use of a claimed Intellectua
17、l 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 not received not
18、ice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2004 All rights reserved. No par
19、t of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. G.7715.1/Y.1706.1 (02/2004) iii CONTENTS Page 1 Introduction 1 2 References. 1 3 Terms and definitions . 2 4 Abbreviations 2 5 Architecture framework for ASON link state routing
20、2 6 Routing hierarchy . 3 7 Identifiers for routing 5 7.1 Identifier spaces 5 7.2 Routing component identifiers . 5 7.3 Name space interaction. 6 7.4 Name spaces and routing hierarchy 6 7.5 SNPP name components. 6 8 Routing within a hierarchy . 6 8.1 Routing information exchange . 6 8.2 LRM to RC co
21、mmunications 9 8.3 Configuring the hierarchy and information flow 9 8.4 Configuring RC adjacencies. 9 9 Routing attributes . 9 9.1 Principles 9 9.2 Taxonomy of attributes. 10 9.3 Common advertisement information 10 9.4 Node attributes 10 9.5 Link attributes. 11 Appendix I Use of SNPP aliases in mult
22、ilevel routing hierarchies 13 Appendix II Multiple RC communications over PCs . 14 Appendix III Example scenarios for RA segmentation, aggregation and evolution of the network hierarchy . 15 III.1 Segregation Insertion of a node in an RA that is “full“. 16 III.2 Merging two RAs . 16 III.3 Renaming a
23、n RA 17 III.4 Insertion Different routing protocol added to a portion of a network . 18 ITU-T Rec. G.7715.1/Y.1706.1 (02/2004) 1 ITU-T Recommendation G.7715.1/Y.1706.1 ASON routing architecture and requirements for link state protocols 1 Introduction ITU-T Recs G.807/Y.1302 and G.8080/Y.1304 specify
24、 the requirements and architecture for a dynamic, automatically switched optical network (ASON) in which connection services are provided using a control plane. ITU-T Rec. G.7715/Y.1706 specifies the requirements and architecture for the ASON routing functions used for the establishment of switched
25、connections and soft permanent connections. This Recommendation provides protocol-neutral requirements for a hierarchical link state routing protocol derived from ITU-T Recs G.8080/Y.1304 and G.7715/Y.1706 in a distributed environment. The distribution of the architectural components is defined in I
26、TU-T Rec. G.8080/Y.1304, and this Recommendation is one realization of the ASON routing architecture. The support of multilevel hierarchical routing is a key function within this instantiation of ITU-T Rec. G.7715/Y.1706. The requirements for link-state routing protocols supporting control plane com
27、munication (i.e., SCN) is not within the scope of this Recommendation. 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
28、 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 ITU-T Recommendat
29、ions 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 Recommendation G.803 (2000), Architecture of transport networks based on the synchronous digital hierarchy (SHD). ITU-T Recommendatio
30、n G.805 (2000), Generic functional architecture of transport networks. ITU-T Recommendation G.807/Y.1302 (2001), Requirements for the automatic switched transport networks (ASTN). ITU-T Recommendation G.872 (2001), Architecture of optical transport networks. ITU-T Recommendation G.7712/Y.1703 (2003)
31、, Architecture and specification of data communication network. ITU-T Recommendation G.7713/Y.1704 (2001), Distributed call and connection management (DCM). ITU-T Recommendation G.7715/Y.1706 (2002), Architecture and requirements for routing in the automatically switched optical networks. ITU-T Reco
32、mmendation G.8080/Y.1304 (2001) and Amendment 1 (2003), Architecture of the automatically switched optical network (ASON). 2 ITU-T Rec. G.7715.1/Y.1706.1 (02/2004) 3 Terms and definitions Terminology Definition Connection Point See ITU-T Rec. G.805 Link Resource Manager See ITU-T Rec. G.8080/Y.1304
33、Protocol Controller See ITU-T Rec. G.8080/Y.1304 Routing Area See ITU-T Rec. G.8080/Y.1304 Routing Controller See ITU-T Rec. G.8080/Y.1304 Routing Database See ITU-T Rec. G.7715/Y.1706 Routing Performer See ITU-T Rec. G.7715/Y.1706 Shared Risk Groups See ITU-T Rec. G.7715/Y.1706 Signalling Communica
34、tion Network See ITU-T Rec. G.7712/Y.1703 Subnetwork Point See ITU-T Rec. G.8080/Y.1304 Subnetwork Point Pool See ITU-T Rec. G.8080/Y.1304 Termination Connection Point See ITU-T Rec. G.805 4 Abbreviations This Recommendation uses the following abbreviations: CC Connection Controller CP Connection Po
35、int IE Information Element LRM Link Resource Manager PC Protocol Controller RA Routing Area RC Routing Controller RDB Routing Information Database RP Routing Performer SCN Signalling Communication Network SNP Subnetwork Point SNPP Subnetwork Point Pool SRG Shared Risk Groups TCP Termination Connecti
36、on Point 5 Architecture framework for ASON link state routing The architectural framework of ITU-T Rec. G.7715/Y.1706 provides a starting point for further architectural analysis. Figure 1 illustrates a Routing Area (RA) in which the Routing Performer (RP) is instantiated via multiple Routing Contro
37、llers (RCs) that belong to the same RA. In this example, two RCs are shown for simplicity. The interaction of functional and G.8080/Y.1304 architectural components related to routing for this RA, described in ITU-T Rec. G.7715/Y.1706, are illustrated. No distinction is made between nodes that may ha
38、ve further internal details ITU-T Rec. G.7715.1/Y.1706.1 (02/2004) 3 (i.e., abstract nodes) and those that cannot be decomposed any further. As described in ITU-T Rec. G.8080/Y.1304, the RC components receive link state information from their associated Link Resource Managers (LRMs) regarding SNPP l
39、inks, and store this information in the Routing Information Database (RDB). The RDB is replicated at each RC within the same RA, and may contain information about multiple network layers in the transport plane. Whenever the state of an SNP changes, the LRM informs the corresponding RC which, in turn
40、, updates its associated RDB. In order to assure RDB synchronization, the RCs cooperate and exchange routing information. In this context, the physical realization of these RC communications is via a particular link state routing protocol. This is represented by the protocol controller (PC) componen
41、t in the G.8080/Y.1304 architecture, and the protocol messages are conveyed over the SCN as described in ITU-T Rec. G.7712/Y.1703. The PC may convey information for one or more network layers (see Appendix II). Path computation functions may exist in each RC, on selected RCs within the same RA, or m
42、ay be centralized for the RA. Path computation on one RC is not dependent on the RDBs in other RCs in the RA. If path computation is centralized, any of the RDBs in the RA (or any instance) may be used. Path computation algorithms are not for standardization and are outside the scope of this Recomme
43、ndation. RC RCPC PCSCNRDBRDBLRM LRMTransport planeControl planeRAExchange ofabstract IEsExchange of protocolmessagesExchange of protocolmessagesTransport plane topology andreachabilityinformation(abstract)nodeExchange ofabstract IEsFigure 1/G.7715.1/Y.1706.1 Example of functional and architectural c
44、omponent interactions within an RA in a single level 6 Routing hierarchy Routing areas allow for information abstraction, enabling information hiding and scalable routing information representation. Except for the single RA case, RAs are hierarchically contained and a separate routing performer is a
45、ssociated with each routing area in the routing hierarchy. It is possible for each level of the hierarchy to employ different routing performers that support different routing paradigms. Routing areas contain routing areas that recursively define successive 4 ITU-T Rec. G.7715.1/Y.1706.1 (02/2004) h
46、ierarchical routing levels. The number of hierarchical levels to be supported is implementation-specific and outside the scope of this Recommendation. In a multilevel routing hierarchy, it is necessary to distinguish among RCs within a level, and RCs at different levels of the routing hierarchy. Bef
47、ore any pair of RCs establishes communication, they must verify they belong to the same RA. An RA identifier (RA ID) is required to provide the scope within which the RCs may communicate. In order to distinguish between RCs within the same RA, an RC identifier (RC ID) is required; the RC ID must be
48、unique within its containing RA. NOTE RA IDs may be associated with a transport plane name space whereas RC IDs are associated with a control plane name space. An illustrative example of a multilevel routing hierarchy where RC identifiers within one RA are reused within another RA, is provided in Fi
49、gure 2. In this particular topology, the RC IDs at hierarchy level N+1 overlap with those used within some of the different level N RAs. (abstract)nodeLevel N+1link #2Level NRAs and RCsLevel N+1RA and RCsRCID = 3RCID = 12RCID = 7RCID = 3RCID = 7RCID = 11RCID = 13RCID = 17RAID = 1313Level N+1 link #1Level N+1link #3RAID = 417Level N+1 link #1Level N+1link #2Level N+1link #3RAID = 2112RAID = 505SNPP link end(abstract) node(abstract)nodeFigure 2/G.7715.1/Y.1706.1 Example network where RC identifiers within one RA are reused within a
