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.800 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (04/2016) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital networks General aspects Unified functional architecture of transport networks R
2、ecommendation ITU-T G.800 ITU-T G-SERIES 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 INTER
3、NATIONAL CARRIER TELEPHONE SYSTEMS ON 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
4、OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 General aspects G.800G.809 Design objectives for digital networks G.810G.819 Synchronization, quality and availability targets G.820G.829 Network capabilities and functions G.830G.839 SDH ne
5、twork characteristics G.840G.849 Management of transport network G.850G.859 SDH radio and satellite systems integration G.860G.869 Optical transport networks G.870G.879 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS
6、G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 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.800 (04/2016) i Recommendation IT
7、U-T G.800 Unified functional architecture of transport networks Summary Recommendation ITU-T G.800 describes a unified functional architecture for transport networks that use connection-oriented circuit switching (CO-CS), connection-oriented packet switching (CO-PS), and connectionless packet switch
8、ing (CL-PS) in a technology-independent way. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T G.800 2007-09-06 15 11.1002/1000/9184 1.1 ITU-T G.800 (2007) Amd. 1 2009-03-09 15 11.1002/1000/9648 1.2 ITU-T G.800 (2007) Amd. 2 2010-09-06 15 11.1002/1000/10878 2.0 ITU-T G.800 201
9、2-02-13 15 11.1002/1000/11489 3.0 ITU-T G.800 2016-04-13 15 11.1002/1000/12790 Keywords Transport architecture, unified functional architecture. _ * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. F
10、or example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T G.800 (04/2016) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Sta
11、ndardization 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 Telecommunication Standardization Assembly (WTSA),
12、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 areas of information technology which fall withi
13、n 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 operating agency. Compliance with this Recommend
14、ation 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 “shall“ or some other obligatory language such as
15、 “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 practice or implementation of this Recommendatio
16、n 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 development process. As of the date of approval of
17、 this Recommendation, ITU had not 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 strongly urged to consult the TSB patent
18、database at http:/www.itu.int/ITU-T/ipr/. ITU 2016 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.800 (04/2016) iii Table of Contents Page 1 Scope . 1 2 References . 1 3 Definitions 1 3.1 Terms im
19、ported from ITU-T G.805 . 1 3.2 Terms defined in this Recommendation . 4 4 Abbreviations and acronyms 5 5 Conventions 6 6 Functional architecture of transport networks 8 6.1 Topological components 9 6.2 Derived network constructs for topological viewpoints . 10 6.3 Transport entities and their prope
20、rties 12 6.4 Transport information entities 16 6.5 Transport processing functions . 17 6.6 Reference points . 19 6.7 Topology . 20 6.8 Layer relationships . 23 6.9 Transport over composite links 25 7 Transparency and impairments . 26 7.1 Interlayer information dependency . 27 8 Sublayers . 28 8.1 Ch
21、annel forwarding 28 8.2 Destination forwarding . 30 9 Transport network availability enhancement techniques . 32 9.1 Differentiated connection protection 32 9.2 Composite link protection 33 Annex A Fundamental concepts used in this Recommendation . 34 A.1 Axioms of the unified architecture . 34 A.2
22、Information . 34 A.3 Encoding and labelling . 36 A.4 Identity and identifiers 38 Annex B Definition and properties of a system 40 B.1 Introduction 40 B.2 Information systems . 41 B.3 Basic transfer function and a telecommunications network . 43 Annex C Communication 47 C.1 Service configuration 47 C
23、.2 Forwarding modes of a transport entity 48 iv Rec. ITU-T G.800 (04/2016) Page C.3 Monitoring of a transport entity . 48 Annex D Transport entity roles . 49 D.1 Overview of transport entity roles 49 D.2 Roles of the transport entity within an operational domain . 49 D.3 Roles of the transport entit
24、y across multiple operational domains . 50 Appendix I Use of identifiers 51 I.1 Use of identifiers 51 Appendix II Relationships between architectural entities. 53 Appendix III Complexity and scalability of systems 55 III.1 Independence of subsystems 56 III.2 Independence within a lifecycle and betwe
25、en lifecycles 56 III.3 Transparency of telecommunications network services . 57 Appendix IV Access points in architecture and equipment Recommendations . 59 Appendix V Examples of roles of the transport entity 61 V.1 Examples of roles of the transport entity within an operational domain 61 V.2 Roles
26、 of transport entities that span multiple operational domains 62 Bibliography. 64 Rec. ITU-T G.800 (04/2016) 1 Recommendation ITU-T G.800 Unified functional architecture of transport networks 1 Scope This Recommendation describes the telecommunication network as a transport network from the viewpoin
27、t of the information transfer capability. A telecommunication network is a complex network that can be described in a number of different ways depending on the particular purpose of the description. This Recommendation provides a set of constructs (definitions and diagrammatic symbols) and the seman
28、tics that can be used to describe such a viewpoint. A transport network transfers user information from a sender at one location to a receiver at another location. A transport network can also transfer various kinds of network control information, such as signalling, and operations and maintenance i
29、nformation for the control functional group. This Recommendation describes the functional architecture of transport networks in a technology-independent way. The generic functional architecture of transport networks provides the basis for a harmonized set of functional architecture Recommendations f
30、or specific layer network technologies, including those that use connection-oriented circuit-switching (CO-CS) or connection-oriented packet-switching (CO-PS) and connectionless packet switching (CL-PS), as well as a corresponding set of Recommendations for management, performance analysis and equip
31、ment specifications. This Recommendation specifies the architectural constructs that are required to describe a transport network. The theoretical material that was used as the basis for these definitions is provided in Annex A (concepts), Annex B (properties of systems) and Annex C (properties of c
32、ommunications). 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 references are su
33、bject 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 reference to a documen
34、t 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.8080 Recommendation ITU-T G.8080/Y.1304 (2012), Architecture for the automatically s
35、witched optical network. ITU-T X.200 Recommendation ITU-T X.200 (1994), Information technology Open Systems Interconnection Basic Reference Model: The basic model. 3 Definitions 3.1 Terms imported from ITU-T G.805 This Recommendation uses the following terms defined elsewhere: 2 Rec. ITU-T G.800 (04
36、/2016) 3.1.1 access group ITU-T G.805: A group of co-located “trail termination“ functions that are connected to the same “subnetwork“ or “link“. 3.1.2 access point ITU-T G.805: A “reference point“ that consists of the pair of co-located “unidirectional access“ points, and therefore represents the b
37、inding between the trail termination and adaptation functions. 3.1.3 adaptation ITU-T G.805: A “transport processing function“ that consists of a co-located adaptation source and sink pair. 3.1.4 adaptation sink ITU-T G.805: A “transport processing function“ which presents the client layer network c
38、haracteristic information at its output by processing the information presented at its input by the server layer network trail. 3.1.5 adaptation source ITU-T G.805: A “transport processing function“ which accepts client layer network characteristic information at its input and processes it to allow
39、transfer over a trail (in the server layer network). 3.1.6 adapted information ITU-T G.805: A signal which is transferred on “trails“. The specific formats will be defined in the technology specific Recommendations. 3.1.7 architectural component ITU-T G.805: Any item used in Recommendation ITU-T G.8
40、05 to generically describe transport network functionality. 3.1.8 binding ITU-T G.805: A direct relationship between a “transport processing function“ or “transport entity“ and another “transport processing function“ or “transport entity“ which represents the static connectivity that cannot be direc
41、tly modified by management action. 3.1.9 characteristic information (CI) ITU-T G.805: A signal with a specific format, which is transferred on “network connections“. The specific formats will be defined in the technology specific Recommendations. NOTE CI consists of adapted information (AI) together
42、 with layer information (LI). 3.1.10 client/server relationship ITU-T G.805: The association between layer networks that is performed by an “adaptation“ function to allow the link connection in the client layer network to be supported by a trail in the server layer network. 3.1.11 connection ITU-T G
43、.805: A “transport entity“ which consists of an associated pair of “unidirectional connections“ capable of simultaneously transferring information in opposite directions between their respective inputs and outputs. 3.1.12 layer network ITU-T G.805: A “topological component“ that represents the compl
44、ete set of access groups of the same type which may be associated for the purpose of transferring information. 3.1.13 link ITU-T G.805: A “topological component“ which describes a fixed relationship between a “subnetwork“ or “access group“ and another “subnetwork“ or “access group“. 3.1.14 matrix IT
45、U-T G.805: It represents the limit to the recursive partitioning of a subnetwork. 3.1.15 matrix connection ITU-T G.805: A “transport entity“ that transfers information across a matrix, it is formed by the association of “ports“ on the boundary of the matrix. NOTE A matrix connection is a type of “su
46、bnetwork connection“. 3.1.16 network ITU-T G.805: All of the entities (such as equipment, plant, facilities) which together provide communication services. 3.1.17 network connection ITU-T G.805: A transport entity formed by a series of contiguous “link connections“ and/or “subnetwork connections“ be
47、tween “termination connection points“. 3.1.18 port ITU-T G.805: It consists of a pair of unidirectional ports. Rec. ITU-T G.800 (04/2016) 3 3.1.19 reference point ITU-T G.805: An architectural component, which is formed by the binding between inputs and outputs of transport processing functions and/
48、or transport entities. 3.1.20 sublayer ITU-T G.805: A set of additional transport processing functions and reference points encapsulated within a layer network. It is created by decomposition of transport processing functions or reference points. 3.1.21 subnetwork ITU-T G.805: A topological componen
49、t used to effect routing of a specific characteristic information. 3.1.22 subnetwork connection ITU-T G.805: A “transport entity“ that transfers information across a subnetwork, it is formed by the association of “ports“ on the boundary of the subnetwork. 3.1.23 topological component ITU-T G.805: An architectural component, used to describe the transport network in terms of the topological relationships between sets of points within the
