1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T I.731TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (10/2000) SERIES I: INTEGRATED SERVICES DIGITAL NETWORK B-ISDN equipment aspects ATM equipment Types and general characteristics of ATM equipment ITU-T Recommendation I.731 (Formerly CCITT Recommendatio
2、n) ITU-T I-SERIES RECOMMENDATIONS INTEGRATED SERVICES DIGITAL NETWORK GENERAL STRUCTURE Terminology I.110I.119 Description of ISDNs I.120I.129 General modelling methods I.130I.139 Telecommunication network and service attributes I.140I.149 General description of asynchronous transfer mode I.150I.199
3、 SERVICE CAPABILITIES Scope I.200I.209 General aspects of services in ISDN I.210I.219 Common aspects of services in the ISDN I.220I.229 Bearer services supported by an ISDN I.230I.239 Teleservices supported by an ISDN I.240I.249 Supplementary services in ISDN I.250I.299 OVERALL NETWORK ASPECTS AND F
4、UNCTIONS Network functional principles I.310I.319 Reference models I.320I.329 Numbering, addressing and routing I.330I.339 Connection types I.340I.349 Performance objectives I.350I.359 Protocol layer requirements I.360I.369 General network requirements and functions I.370I.399 ISDN USER-NETWORK INTE
5、RFACES Application of I-series Recommendations to ISDN user-network interfaces I.420I.429 Layer 1 Recommendations I.430I.439 Layer 2 Recommendations I.440I.449 Layer 3 Recommendations I.450I.459 Multiplexing, rate adaption and support of existing interfaces I.460I.469 Aspects of ISDN affecting termi
6、nal requirements I.470I.499 INTERNETWORK INTERFACES I.500I.599 MAINTENANCE PRINCIPLES I.600I.699 B-ISDN EQUIPMENT ASPECTS ATM equipment I.730I.739 Transport functions I.740I.749 Management of ATM equipment I.750I.759 Multiplexing aspects I.760I.769 For further details, please refer to the list of IT
7、U-T Recommendations. ITU-T I.731 (10/2000) i ITU-T Recommendation I.731 Types and general characteristics of ATM equipment Summary This Recommendation describes the types and characteristics of ATM Network Elements (NE) in terms of functional requirements. Source ITU-T Recommendation I.731 was revis
8、ed by ITU-T Study Group 15 (1997-2000) and approved by the World Telecommunication Standardization Assembly (Montreal, 27 September 6 October 2000). ITU-T I.731 (10/2000) iiFOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunica
9、tions. 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 Telecommunicati
10、on 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 areas of inf
11、ormation 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 operating ag
12、ency. 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, validity or applicability of claimed Intellectual Property
13、 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 required to implement this Recommendation. However, implem
14、entors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. Ge3 ITU 2001 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including ph
15、otocopying and microfilm, without permission in writing from ITU. ITU-T I.731 (10/2000) iii CONTENTS Page 1 Scope. 1 2 References. 1 3 Abbreviations 3 4 Definitions 4 5 ITU-T I.732 Annex D formal model. 4 5.1 Symbols and diagrammatic conventions. 4 5.2 Functional modelling rationale . 4 6 Overview o
16、f equipment functions. 5 6.1 Transfer functions . 5 6.2 Layer Management functions 5 6.3 ATM Equipment Management Function (AEMF) . 5 6.4 Message Communications Function. 6 6.5 Coordination function. 6 6.6 Connection Admission Control (CAC) function 6 6.7 Signalling Application 6 6.8 Timing function
17、 6 6.9 Interworking functions 7 7 Connection types and characteristics 7 7.1 Connection types. 7 7.1.1 Point-to-point connections. 10 7.1.2 Point-to-multipoint connections 10 7.1.3 Multipoint-to-point connections 11 7.1.4 Multipoint-to-multipoint connections . 14 7.1.5 OAM aspects of multipoint conn
18、ections . 14 7.2 Methods of establishing connections 14 7.2.1 Permanent Virtual Connections (PVC) . 14 7.2.2 Switched virtual connections. 15 7.3 Transfer Capabilities. 15 8 OAM functions . 15 8.1 OAM naming conventions for ATM 16 8.2 OAM procedures. 16 8.2.1 AIS application 16 8.2.2 RDI application
19、 16 8.2.3 CC application . 16 ITU-T I.731 (10/2000) ivPage 8.2.4 LB application . 17 8.2.5 Performance Management application 17 9 Protection switching and restoration. 17 9.1 Trail VP and VC individual protection (1+1/1:1 trail) . 17 9.2 Segment VP and VC individual protection (1+1/1:1 SNC/S) 17 9.
20、3 Subnetwork VP and VC individual protection (1+1 SNC/N). 17 9.4 Trail VP and VC group protection (1+1/1:1 trail/T). 19 9.5 Subnetwork VP and VC group protection (1+1/1:1 SNC/T) 19 10 Traffic measurement functions . 21 10.1 Traffic information collection. 21 10.1.1 TP usage measurement 21 10.1.2 ATM
21、 cell level procedure performance information collection 21 10.1.3 VP and VC traffic load information collection 22 10.1.4 VP and VC UPC/NPC information collection 22 10.1.5 Call level information collection . 23 11 Generic performance requirements. 23 11.1 Quality of Service aspects. 23 11.2 ATM Ne
22、twork Element performance objectives 23 11.2.1 Cell loss objectives, cell transfer objectives and CDV objectives. 24 11.2.2 Semi-permanent connection availability . 24 11.2.3 Call processing performance . 24 12 Timing and synchronization requirements 25 12.1 User plane related timing 25 12.1.1 Timin
23、g accuracy 25 12.1.2 Equipment timing source. 25 12.1.3 Timing of the TP layers . 26 12.2 Management of plane related timing 26 13 Availability and reliability 26 13.1 Availability objectives 26 13.2 Data integrity. 26 13.3 Upgrade. 27 13.3.1 Hardware upgrade 27 13.3.2 Software upgrade. 27 13.4 Star
24、t-up requirements 27 ITU-T I.731 (10/2000) v Page Appendix I ATM layer cell transfer performance. 28 Appendix II Bibliography . 29 ITU-T I.731 (10/2000) viIntroduction This Recommendation gives an overview of the functions of ATM equipment, examples of overall characteristics and objectives for ATM
25、network elements. The general characteristics of ATM equipment may be described by using the functional partitioning of the network element into logical functions linked by internal communications between the functions. A general methodology which may be used to clarify the different types of ATM eq
26、uipment is also contained in ITU-T I.732. The grouping of functional functions in accordance with the B-ISDN Protocol Reference Model and the detailed modelling methodology of ITU-T I.326 enables the description of any ATM equipment to the required level of detail. ITU-T I.731 (10/2000) 1ITU-T Recom
27、mendation I.731 Types and general characteristics of ATM equipment 1 Scope The purpose of ITU-T I.731 and I.732 is to describe the functional requirements to enable the interoperability between ATM network elements. The detailed functional characteristics of ATM equipment are contained in ITU-T I.73
28、2. ITU-T I.731 is more generalized, providing introductions and covering terms and concepts that did not easily fit into the structure of ITU-T I.732. ITU-T I.731 introduces the functional model used in ITU-T I.732 and in other technologies such as SDH and provides an overview of ATM equipment. ITU-
29、T I.731 describes how the functional model can be used to model multipoint communications. This includes how to handle the so-called “channel merging“ without corrupting the traffic and without requiring special functions. ITU-T I.731 also provides modelling for OAM applications showing how the vari
30、ous functions in the library can be joined together in different network elements to form an OAM application such as AIS. ITU-T I.731 also describes protection switching of ITU-T I.630 using the functional modelling technique. This Recommendation is an update to ITU-T I.731/1995 which was the overvi
31、ew companion to ITU-T I.732/1995. This update has resulted in some sections moving from ITU-T I.732. 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 publicatio
32、n, the editions indicated were valid. All Recommendations and other references are subject to revision; all 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
33、 currently valid ITU-T Recommendations is regularly published. 1 ITU-T G.703 (1998), Physical/electrical characteristics of hierarchical digital interfaces. 2 ITU-T G.704 (1998), Synchronous frame structures used at 1544, 6312, 2048, 8448 and 44 736 kbit/s hierarchical levels. 3 ITU-T G.707/Y.1322 (
34、2000), Network node interface for the Synchronous Digital Hierarchy (SDH). 4 ITU-T G.773 (1993), Protocol suites for Q-interfaces for management of transmission systems. 5 ITU-T G.781 (1999), Synchronization layer functions. 6 ITU-T G.783 (2000), Characteristics of Synchronous Digital Hierarchy (SDH
35、) equipment functional blocks. 7 ITU-T G.784 (1999), Synchronous Digital Hierarchy (SDH) management. 8 ITU-T G.804 (1998), ATM cell mapping into Plesiochronous Digital Hierarchy (PDH). 9 ITU-T G.805 (2000), Generic functional architecture of transport networks. 10 ITU-T G.806 (2000), Characteristics
36、 of transport equipment Description methodology and generic functionality. 11 ITU-T G.832 (1998), Transport of SDH elements on PDH networks Frame and multiplexing structures. ITU-T I.731 (10/2000) 212 ITU-T G.957 (1999), Optical interfaces for equipments and systems relating to the synchronous digit
37、al hierarchy. 13 ITU-T I.150 (1999), B-ISDN asynchronous transfer mode functional characteristics. 14 ITU-T I.211 (1993), B-ISDN service aspects. 15 ITU-T I.311 (1996), B-ISDN general network aspects. 16 ITU-T I.321 (1991), B-ISDN protocol reference model and its application. 17 ITU-T I.326 (1995),
38、Functional architecture of transport networks based on ATM. 18 ITU-T I.327 (1993), B-ISDN functional architecture. 19 ITU-T I.356 (2000), B-ISDN ATM layer cell transfer performance. 20 ITU-T I.361 (1999), B-ISDN ATM layer specification. 21 ITU-T I.363 (2000), B-ISDN ATM Adaptation Layer (AAL) specif
39、ication. 22 ITU-T I.371 (2000), Traffic control and congestion control in B-ISDN. 23 ITU-T I.413 (1993), B-ISDN user-network interface. 24 ITU-T I.432 (1997), B-ISDN user-network interface Physical layer specification. 25 ITU-T I.555 (1997), Frame Relaying Bearer Service interworking. 26 ITU-T I.580
40、 (1995), General arrangements for interworking between B-ISDN and 64 kbit/s based ISDN. 27 ITU-T I.610 (1999), B-ISDN operation and maintenance principles and functions. 28 ITU-T I.732 (2000), Functional characteristics of ATM equipment. 29 ITU-T I.751 (1996), Asynchronous transfer mode management o
41、f the network element view. 30 ITU-T M.3010 (2000), Principles for a telecommunications management network. 31 ITU-T Q.811 (1997), Lower layer protocol profiles for the Q3 and X interfaces. 32 ITU-T Q.812 (1997), Upper layer protocol profiles for the Q3 and X interfaces. 33 ITU-T Q.2100 (1994), B-IS
42、DN signalling ATM adaptation layer (SAAL) Overview description. 34 ITU-T Q.2144 (1995), B-ISDN signalling ATM adaptation layer Layer management for the SAAL at the network node interface. 35 ITU-T Q.2761 (1999), Functional description of the B-ISDN User Part (B-ISUP) of Signalling System No. 7. 36 I
43、TU-T Q.2762 (1999), General functions of messages and signals of the B-ISDN User Part (B-ISUP) of Signalling System No. 7. 37 ITU-T Q.2763 (1999), Signalling System No. 7 B-ISDN User Part (B-ISUP) Formats and codes. 38 ITU-T Q.2764 (1999), Signalling System No. 7 B-ISDN User Part (B-ISUP) Basic call
44、 procedures. 39 ITU-T Q.2931 (1995), Digital Subscriber Signalling System No. 2 User-Network Interface (UNI) layer 3 specification for basic call/connection control. 40 ITU-T X.25 (1996), Interface between Data Terminal Equipment (DTE) and Data Circuit-terminating Equipment (DCE) for terminals opera
45、ting in the packet mode and connected to public data networks by dedicated circuit. ITU-T I.731 (10/2000) 33 Abbreviations This Recommendation uses the following abbreviations: AAL ATM Adaptation Layer ABR Available Bit Rate ACC Accounting Management AEMF ATM Equipment Management Function AIS Alarm
46、Indication Signal ATM Asynchronous Transfer Mode B-ISDN Broadband Integrated Services Digital Network B-UNI Broadband User Network Interface CAC Connection Admission Control CBR Constant Bit Rate CDV Cell Delay Variation CLR Cell Loss Ratio CoF Coordination Function CONFIG Configuration CTD Cell Tra
47、nsfer Delay DBR Deterministic Bit Rate ETPI Equipment Timing Physical Interface ETS Equipment Timing Source FM Fault Management FMBS Frame Mode Bearer Service HEC Header Error Control ISDN Integrated Services Digital Network IWF InterWorking Function LMI Layer Management Indication MCF Message Commu
48、nications Function NE Network Element NNI Network Node Interface NPC Network Parameter Control OAM Operations And Maintenance PDH Plesiochronous Digital Hierarchy PDU Protocol Data Unit PM Performance Management QOS Quality Of Service RM Resource Management SAAL B-ISDN signalling ATM Adaptation laye
49、r ITU-T I.731 (10/2000) 4SAP Service Access Point SBR Statistical Bit Rate SDH Synchronous Digital Hierarchy SDU Service Data Unit TM Transmission Media TMN Telecommunications Management Network TP Transmission Path UBR Unspecified Bit Rate UNI User Network Interface UPC Usage Parameter Control VBR Variable Bit Rate VC Virtual Channel VP Virtual Path 4 Definitions This Recommendation defines the following terms: 4.1 ATM resource request: request to establish
