1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T G.7715/Y.1706TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (06/2002) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital terminal equipments Operations, administration and maintenance features of transmission equipment SERIES
2、Y: GLOBAL INFORMATION INFRASTRUCTURE AND INTERNET PROTOCOL ASPECTS Internet protocol aspects Operation, administration and maintenance Architecture and requirements for routing in the automatically switched optical networks ITU-T Recommendation G.7715/Y.1706 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSI
3、ON 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 GEN
4、ERAL 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 DIGITAL TERMIN
5、AL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 QUALITY OF SERVICE AND PERFORMANCE G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DIGITAL TERMINAL EQUIPMENTS G.7000G.7999 General G.7000G.7099 Coding of analogue signals by pulse c
6、ode 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 characteristics of higher order multiplex equipment
7、 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 synchronous digital hierarchy G.7800G.7899 Ot
8、her 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/Y.1706 (06/2002) i ITU-T Recommendation G.7715/Y.1706 Architecture and requirements for routing in the automatically switched optical networks S
9、ummary This Recommendation specifies the requirements and architecture for the routing functions used for the establishment of switched connections (SC) and soft permanent connections (SPC) within the framework of the Automatically Switched Optical Network (ASON). The main areas covered in this Reco
10、mmendation include the ASON routing architecture, functional components including path selection, routing attributes, abstract messages and state diagrams. This Recommendation forms a part of the suite of Recommendations covering the full functionality of the automatic switched transport network (AS
11、TN) and the automatic switched optical network (ASON). Source ITU-T Recommendation G.7715/Y.1706 was prepared by ITU-T Study Group 15 (2001-2004) and approved under the WTSA Resolution 1 procedure on 13 June 2002. Keywords Automatic Switched Optical Network, Automatic Switched Transport Network, Net
12、work-Network Interface (NNI), Network Resources, Path Selection, Routing, Routing Area, Routing Attributes, Routing Control Domain, Routing Controller, Routing Messages, Routing State Machine, User Network Interface (UNI). ii ITU-T Rec. G.7715/Y.1706 (06/2002) FOREWORD The International Telecommunic
13、ation Union (ITU) is the United Nations specialized agency in the field of telecommunications. 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
14、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 approval of ITU-T Recommen
15、dations 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 “Administration“ is used for conci
16、seness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS ITU 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 posi
17、tion 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 notice of intellectual property, prote
18、cted 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 2002 All rights reserved. No part of this publication may be reprod
19、uced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. G.7715/Y.1706 (06/2002) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Terms and definitions . 2 4 Abbreviations 3 5 ASON routing architecture. 3 5.1 Fundamental concepts 3 5.2 Routing architecture and functional c
20、omponents . 5 5.2.1 Considerations for different protocols 6 5.2.2 Considerations for multiple VPNs 7 5.2.3 Considerations for policy . 7 5.3 Routing area hierarchies. 7 5.3.1 Routing performer realization in relation to routing Area hierarchies. 8 5.3.2 Correspondence between LRM and RCs for hierar
21、chical routing areas 9 6 ASON routing requirements. 10 6.1 Architectural requirements . 10 6.2 Protocol requirements. 11 6.3 Path selection requirements 11 7 Routing attributes . 11 7.1 Node attributes 11 7.1.1 Reachability attributes 12 7.1.2 Diversity related attributes . 12 7.1.3 Other attribute
22、information. 12 7.2 Link attributes. 12 7.2.1 Link state 12 7.2.2 Diversity related attributes . 13 7.2.3 Other attribute information. 13 8 Routing messages . 13 8.1 Routing adjacency maintenance. 14 8.2 Routing information messages . 14 8.3 Routing exception and error handling 15 8.4 State diagrams
23、 15 8.4.1 Information element transmission 15 8.4.2 Information element reception . 16 8.4.3 Local information element transmission generation 17 iv ITU-T Rec. G.7715/Y.1706 (06/2002) Page 9 Routing message distribution topology 18 9.1 Congruent topology 18 9.2 Hubbed topology using a routing messag
24、e server 19 9.3 Directed topology . 19 10 Path selection 20 10.1 Inputs to path selection. 20 10.1.1 Step-by-step routing . 20 10.1.2 Source and hierarchical routing 21 10.2 Output of path selection 21 10.3 Routing paradigms and path selection 22 Appendix I Information flow between levels of the rou
25、ting hierarchy. 22 I.1 Information dissemination related to resolving end-point addresses . 23 I.1.1 Parent to child information flow. 23 I.1.2 Child to parent information flow 23 I.2 Information exchange between hierarchical levels for resolving end-point addresses. 24 Appendix II Shared Risk Group
26、 25 II.1 Path diversity 25 II.2 Network resources and risk sharing . 25 II.3 Shared Risk Group (SRG) 26 II.4 SRG implications for routing . 26 ITU-T Rec. G.7715/Y.1706 (06/2002) 1 ITU-T Recommendation G.7715/Y.1706 Architecture and requirements for routing in the automatically switched optical netwo
27、rks 1 Scope This Recommendation specifies the requirements and architecture for the routing functions used for the establishment of switched connections (SC) and soft permanent connections (SPC) within the framework of the Automatically Switched Optical Network (ASON). The main areas covered in this
28、 Recommendation include the ASON routing architecture, functional components including path selection, routing attributes, abstract messages and state diagrams. This Recommendation forms a part of the suite of Recommendations covering the full functionality of the automatic switched transport networ
29、k and the automatic switched optical network. It builds upon the high-level functional requirements and architecture as outlined in ITU-T Recs G.807/Y.1302 (ASTN) and G.8080/Y.1304 (ASON) as the baseline framework for the specification. This Recommendation is aimed at providing a protocol neutral ap
30、proach to describe routing for the automatic switched optical networks. Routing messages are transported over a data communication network (DCN). One possible implementation is specified in ITU-T Rec. G.7712/Y.1703. In order to provide routing service, a priori knowledge of the network resources is
31、needed. These resources may be manually provisioned or automatically discovered. ASON routing has many applications, e.g. traffic engineering, diverse routing, etc. However details of these applications are beyond the scope of this Recommendation. 2 References The following ITU-T Recommendations and
32、 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 are therefore encour
33、aged 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. ITU-T Recommendation G.805 (2000), Generic functional architecture of transport networks. ITU-
34、T Recommendation G.807/Y.1302 (2001), Requirements for Automatic Switched Transport Networks (ASTN). ITU-T Recommendation G.851.1 (1996), Management of the transport network Application of RM-ODP framework. ITU-T Recommendation G.7712/Y.1703 (2001), Architecture and specification of Data Communicati
35、on Network (DCN). ITU-T Recommendation G.8080/Y.1304 (2001), Architecture of the Automatically Switched Optical Network (ASON). ITU-T Recommendation M.3016 (1998), TMN security overview. ITU-T Recommendation X.800 (1991), Security architecture for Open Systems Interconnection (OSI) for CCITT applica
36、tions. 2 ITU-T Rec. G.7715/Y.1706 (06/2002) 3 Terms and definitions 3.1 This Recommendation uses the following terms defined in ITU-T Rec. G.805: a) Administrative Domain; b) Link; c) Link Connection (LC); d) Partitioning; e) Subnetwork; f) Subnetwork Connection (SNC). 3.2 This Recommendation uses t
37、he following term defined in ITU-T Rec. G.851.1: a) Cluster. 3.3 This Recommendation uses the following term defined in ITU-T Rec. G.7712/Y.1703: a) Data Communication Network (DCN). 3.4 This Recommendation uses the following terms defined in ITU-T Rec. G.8080/Y.1304: a) Connection Controller; b) Fe
38、deration; c) Link Resource Manager (LRM); d) Protocol Controller (PC); e) Routing Area; f) Routing Controller (RC); g) Routing Information Database (RDB); h) Subnetwork Point Pool (SNPP); i) Subnetwork Point (SNP); j) Virtual Private Network (VPN). 3.5 This Recommendation defines the following terms
39、: 3.5.1 node: In the context of this Recommendation, the term node is used to signify a subnetwork or a Routing Area. 3.5.2 Routing Adjacency (RAdj): A logical association between two Routing Controllers. 3.5.3 Routing Control Domain (RCD): An abstract entity that hides the details of the RC distrib
40、ution. See 5.1 for more information. 3.5.4 Routing Performer (RP): A computational viewpoint object (per ITU-T Rec. G.851.1) that is associated with a routing area and provides an abstraction of the routing service for the routing area. 3.5.5 Shared Risk Group (SRG): A group of resources that share
41、a common risk component whose failure can cause the failure of all the resources in the group. ITU-T Rec. G.7715/Y.1706 (06/2002) 3 4 Abbreviations This Recommendation uses the following abbreviations: AD Administrative Domain ASON Automatically Switched Optical Network ASTN Automatic Switched Trans
42、port Network DCN Data Communication Network E-NNI External Network-Network Interface IE Information Element I-NNI Internal Network-Network Interface LRM Link Resource Manager RA Routing Area RAdj Routing Adjacency RC Routing Controller RCD Routing Control Domain RDB Routing Information Database RI R
43、outing Information RP Routing Performer SNP Subnetwork Point SNPP Subnetwork Point Pool SRG Shared Risk Group UNI User Network Interface VPN Virtual Private Network 5 ASON routing architecture The ASON routing architecture supports various routing paradigms listed in ITU-T Rec. G.8080/Y.1304, e.g. h
44、ierarchical, step-by-step and source-based. The architecture also abstracts away differences in routing information representation, e.g. link-state, distance-vector, etc. The routing architecture applies after the network has been subdivided into routing areas, and the necessary network resources ha
45、ve been accordingly assigned. The process of subdividing the network into routing areas and assigning network resources is beyond the scope of this Recommendation. 5.1 Fundamental concepts An operator may choose to subdivide its network based upon specific operator policies, which could include such
46、 criteria as geography, administration, technology, etc. The network subdivisions may, by operator decision, be treated as routing areas for the purpose of providing a routing service. Routing areas provide for routing information abstraction, thereby enabling scalable routing information representa
47、tion. The service offered by a routing area (e.g. path selection) is provided by a Routing Performer (a federation of Routing Controllers), and each Routing Performer is responsible for a single routing area. The RP supports path computation functions consistent with one or more of the routing parad
48、igms listed in ITU-T Rec. G.8080/Y.1304 (source, hierarchical and step-by-step) for the particular routing area that it provides service for. The path computation 4 ITU-T Rec. G.7715/Y.1706 (06/2002) functions that may be supported by a RP are based upon the types of information available to it via
49、a Routing Information Database. Routing areas may be hierarchically contained and a separate Routing Performer is associated 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 Performers are realized through the instantiation of possibly distributed Routing Controllers. The Routing Controller provides the routing service interface, i.e. the service access point, as defined for the Routing Performer. The Routing
