1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T G.809TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (03/2003) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital networks General aspects Functional architecture of connectionless layer networks ITU-T Recommendation G.809 ITU-
2、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 INTERNATIONAL CARRIER TELEPHONE SYS
3、TEMS 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 TESTING EQUIPMENTS G.500G.599 TRANSMISSION MEDIA CHAR
4、ACTERISTICS 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 Quality and availability targets G.820G.829 Network capabilities and functions G.830G.839 SDH network characteristics G.840G.849 Mana
5、gement 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 QUALITY OF SERVICE AND PERFORMANCE G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DIGITAL TERMINAL EQU
6、IPMENTS G.7000G.7999 DIGITAL NETWORKS G.8000G.8999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. G.809 (03/2003) i ITU-T Recommendation G.809 Functional architecture of connectionless layer networks Summary This Recommendation describes the functional architectur
7、e of a connectionless transport network from the viewpoint of its information transfer capability. The functional and structural architecture of these networks is described independently of networking technology. As such, the Recommendation should be taken as the basis for technology-specific descri
8、ptions of connectionless transport networks. Source ITU-T Recommendation G.809 was prepared by ITU-T Study Group 13 (2001-2004) and approved under the WTSA Resolution 1 procedure on 22 March 2003. ii ITU-T Rec. G.809 (03/2003) FOREWORD The International Telecommunication Union (ITU) is the United Na
9、tions 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 view to standardizing telecommunic
10、ations 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 Recommendations is covered by the procedur
11、e 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 conciseness to indicate both a telecomm
12、unication 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 position concerning the evidence, vali
13、dity 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, protected by patents, which may be requ
14、ired 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 2003 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, wit
15、hout the prior written permission of ITU. ITU-T Rec. G.809 (03/2003) iii CONTENTS Page 1 Scope 1 2 References. 1 3 Definitions 2 4 Abbreviations 4 5 Conventions 4 6 Functional Architecture of connectionless layer networks. 4 6.1 Introduction 4 6.2 Relationship between connection-oriented and connect
16、ionless layer networks . 4 6.3 Architectural components. 5 6.4 Partitioning and layering 11 6.5 Decomposition of connectionless layer networks 16 6.6 Application of concepts to network topologies and structures. 16 Annex A Characteristics of connectionless and connection-oriented layer networks 17 A
17、.1 Characteristics of a CO-CS network implemented with SDH, OTN or PDH 18 A.2 Characteristics of a CO-PS network implemented with ATM. 18 A.3 Characteristics of a CLPS network implemented with IP using best effort, destination-based forwarding . 19 A.4 Characteristics of a network implemented with e
18、thernet . 19 Annex B Components of connection-oriented and connectionless layer networks 21 ITU-T Rec. G.809 (03/2003) 1 ITU-T Recommendation G.809 Functional architecture of connectionless layer networks 1 Scope This Recommendation describes the functional architecture of connectionless layer netwo
19、rks using the methodology described in ITU-T Rec. G.805. The concept of the connection is central to the functional architecture described in ITU-T Rec. G.805 and in order to provide a common framework between the connection-oriented layer networks and a connectionless layer network, it is necessary
20、 to introduce new concepts that describe connectionless behaviour. The connectionless transport network functionality is described from a network level viewpoint, taking into account layer network structure, networking topology, client characteristic information, client/server layer associations and
21、 mapping between connectionless and connection-oriented layer networks. This Recommendation describes the functional architecture of connectionless transport networks in a technology independent way. As such, it forms the basis for a set of Recommendations for management, performance analysis and eq
22、uipment specifications related to specific connectionless technologies. The extension of the methodology defined in ITU-T Rec. G.805 for connectionless layer networks allows for the description of equipment containing both connection-oriented and connectionless technologies in a common way. If this
23、Recommendation is used as the basis for developing a technology-specific Recommendation to describe and model networks that use existing protocols (such as IP, Ethernet, Token Ring, etc.) it shall be used in a manner that is fully consistent with existing specifications as approved by the relevant s
24、tandards organizations. The use of this Recommendation is not intended to provide a means by which existing protocols and architectures are modified. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions
25、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 edition of the Recommendations and
26、 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 Recommendation G.803 (2000), Architecture of transport
27、 networks based on the synchronous digital hierarchy (SDH). ITU-T Recommendation G.805 (2000), Generic functional architecture of transport networks. ITU-T Recommendation G.8080/Y.1304 (2001), Architecture for the automatically switched optical networks (ASON). ITU-T Recommendation I.326 (2003), Fun
28、ctional architecture of transport networks based on ATM. ITU-T Recommendation X.200 (1994) | ISO/IEC 7498-1:1994, Information technology Open Systems Interconnection Basic Reference Model: The basic model. 2 ITU-T Rec. G.809 (03/2003) 3 Definitions NOTE 1 Where a definition contains a term which is
29、itself defined, that term is given in quotation marks. NOTE 2 The terms can be further qualified by reference to a specific layer network by adding the appropriate layer network qualifier. NOTE 3 All architectural components are unidirectional. NOTE 4 The definitions only apply to connectionless lay
30、er networks. Definitions for connection-oriented networks are as described in ITU-T Rec. G.805. This Recommendation defines the following terms: 3.1 access group: A group of colocated “flow termination“ functions that are attached to the same “flow domain“ or “ flow point pool link“. 3.2 access poin
31、t: A “reference point“ that represents the binding between the flow termination and adaptation functions. 3.3 adaptation: A “transport processing function“. There are two types of adaptation, an adaptation sink and an adaptation source. 3.4 adaptation sink: A “transport processing function“ which pr
32、esents the client layer network characteristic information at its output by processing the information presented at its input by the server layer network trail. 3.5 adaptation source: A “transport processing function“ which accepts client layer network characteristic information at its input and pro
33、cesses it to allow transfer over a trail (in the server layer network). 3.6 adapted information: A signal which is transferred on “trails“ or “connectionless trails“. The specific formats will be defined in the technology specific recommendations. 3.7 architectural component: Any item used in this R
34、ecommendation to generically describe transport network functionality. 3.8 binding: A direct relationship between a “transport processing function“ or “transport entity“ and another “transport processing function“ or “transport entity“ which represents static associations that cannot be directly mod
35、ified by management action. 3.9 characteristic information: A signal with a specific format, which is transferred on “flows“. The specific formats will be defined in the technology specific Recommendations. 3.10 client/server relationship: The association between layer networks that is performed by
36、an “adaptation“ function to allow the “flow“ in the client layer network to be supported by a trail in the server layer. 3.11 connectionless trail: A “transport entity“ responsible for the transfer of information from the input of a flow termination source to the output of a flow termination sink. T
37、he integrity of the information transfer may be monitored. 3.12 flow: An aggregation of one or more traffic units with an element of common routing. 3.13 flow domain: A topological component used to effect forwarding of a specific characteristic information. 3.14 flow domain flow: A “transport entit
38、y“ that transfers information across a flow domain, it is formed by the association of “ports“ on the boundary of the flow domain. 3.15 flow point: A “reference point“ that represents a point of transfer for traffic units between topological components. 3.16 flow point pool: A group of colocated flo
39、w points that have a common routing. ITU-T Rec. G.809 (03/2003) 3 3.17 flow point pool link: A “topological component“ which describes a fixed relationship between a “flow domain“ or “access group“ and another “flow domain“ or “access group“. 3.18 flow termination: A “transport processing function“.
40、 There are two types of flow termination, a flow termination sink and a flow termination source. 3.19 flow termination sink: A “transport processing function“ which accepts the “characteristic information“ of the layer network at its input, recovers the information related to “connectionless trail“
41、monitoring and presents the remaining information at its output. 3.20 flow termination source: A “transport processing function“ which accepts adapted “characteristic information“ from a client layer network at its input, adds information to allow the “connectionless trail“ to be monitored and prese
42、nts the characteristic information of the layer network at its output(s). 3.21 layer network: A “topological component“ that represents the complete set of access groups of the same type which may be associated for the purpose of transferring information. 3.22 link flow: A “transport entity“ that tr
43、ansfers information between “ports“ across a flow point pool link. 3.23 matrix: It represents the limit to the recursive partitioning of a flow domain. 3.24 matrix flow: A “transport entity“ that transfers information across a matrix, it is formed by the association of ports on the boundary of the m
44、atrix. 3.25 network: All of the entities (such as equipment, plant, facilities) which together provide communication services. 3.26 network flow: A transport entity formed by a series of contiguous “flows“ between “termination flow points“. 3.27 port: It represents the output of a flow termination s
45、ource or flow domain or the input to a flow termination sink or flow domain. 3.28 reference point: An architectural component, which is formed by the binding between inputs and outputs of transport processing functions and/or transport entities. 3.29 topological component: An architectural component
46、, used to describe the transport network in terms of the topological relationships between sets of points within the same layer network. 3.30 traffic unit: An instance of characteristic information and a unit of usage. 3.31 transport: The functional process of transferring information between differ
47、ent locations. 3.32 transport entity: An architectural component which transfers information between its inputs and outputs within a layer network. 3.33 transport network: The functional resources of the network which conveys user information between locations. 3.34 transport processing function: An
48、 architectural component defined by the information processing which is performed between its inputs and its outputs. Either the input or the output must be inside a layer network. 3.35 termination flow point: A reference point that represents the binding of a flow termination to a flow. 4 ITU-T Rec
49、. G.809 (03/2003) 4 Abbreviations This Recommendation uses the following abbreviations: AP Access Point CLPS Connectionless packet switched CO-CS Connection-oriented circuit switched CO-PS Connection-oriented packet switched CP Connection Point FP Flow Point FPP Flow Point Pool FPP link Flow Point Pool link TCP Termination Connection Point TFP Termination Flow Point 5 Conventions The diagrammatic convention for connection-oriented layer networks described in this Recommendation is that of ITU-T Rec. G.805. 6 Functional Architecture of connec
