1、INTERNATIONAL TELECOMMUNICATION UNION ITU=T TE LECOMMUN KATION STANDARDIZATION SECTOR OF ITU SERIES I: INTEGRATED SERVICES DIGITAL NETWORK Overall network aspects and functions - Network functional principles 1.31 1 (08/96) B-ISDN general network aspects ITU-T Recommendation 1.31 1 (Previously CCITT
2、 Recommendation) STD-ITU-T RECMN 1.311-ENGL 199L W 4db259L Ob51532 95T ITU-T I-SERIES RECOMMENDATIONS INTEGRATED SERVICES DIGITAL NETWORK GENERAL STRUCTURE Terminology Description of ISDNs General modelling methods Telecommunication network and service attributes General description of asynchronous
3、transfer mode Scope General aspects of services in ISDN Common aspects of services in the ISDN Bearer services supported by an ISDN Teleservices supported by an ISDN Supplementary services in ISDN SERVICE CAPABILITIES OVERALL NETWORK ASPECTS AND FUNCTIONS 1.1 00-1.1 99 I. 1 10-1.1 19 1.1 20-1.1 29 I
4、. 1 30-1.139 1.1 40-1.149 1.1 50-1.199 I .200-1.299 1.200-1.209 1.210-1.21 9 1.220-1.229 I .230-1.239 1.240-1.249 I .25O-l .299 1.300-1.399 II Network functional principles 1.310-1.319 Reference models Numbering, addressing and routing Connection types Performance objectives Protocol layer requireme
5、nts General network requirements and functions Application of I-series Recommendations to ISDN user-network interfaces Layer 1 Recommendations Layer 2 Recommendations Layer 3 Recommendations Multiplexing, rate adaption and support of existing interfaces Aspects of ISDN affecting terminal requirement
6、s ISDN USER-NETWORK INTERFACES INTERNETWORK INTERFACES MAINTENANCE PRINCIPLES B-ISDN EQUIPMENT ASPECTS ATM equipment Management of ATM equipment I .32O-l.329 1.330-1.339 1.340-1.349 1.350-1.359 1.360-1.369 I .370-1.399 I .400-1.499 1.420-1.429 1.430-1.439 1.440-1.449 1.450-1.459 I .460-1.469 1.470-1
7、.499 I .50O-l 599 I .600-1.699 I .70O-l.799 I .730-1.749 I .750-1.799 II For further details, please refer to ITU-T List of Recommendations. ITU-T RECOMMENDATION 1.311 E-ISDN GENERAL NETWORK ASPECTS Source ITU-T Recommendation 1.31 1 was revised by ITU-T Study Group 13 (1993-1996) and was approved u
8、nder the WTSC Resolution No. 1 procedure on the 27th of August 1996. STD- ITU-T RECMN I-3LL-ENGL 177L M 4b2.591 ObC1.534 FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector
9、(ITU-T) is a permanent organ of the ITU. The 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 Conference (WTSC), which meet
10、s every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. In some areas of information techn
11、ology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLEC
12、TUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Right
13、s, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, the ITU hadhad not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, imple
14、mentors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. O ITU 1997 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including pho
15、tocopying and microfilm, without permission in writing from the ITU. 11 Recommendation 1.311 (08/96) 1 1.1 1.2 1.3 1.4 1.5 1.6 2 2.1 2.2 3 3.1 3.2 3.3 4 4.1 4.2 4.3 4.4 4.5 4.6 5 CONTENTS Network Layering . General Architectural components of an ATM transport network . ATM Layer . 1.3.1 Virtual chan
16、nel level 1.3.2 Virtual path level . Physical Layer . 1.4.1 Transmission path level . 1.4.2 Digital section level . 1.4.3 Regenerator section level . Hierarchical level-to-level relationship . Functional description of the layered network connecting point functions. Functions at the connecting point
17、 Application of virtual channel connections and virtual path connections Applications of virtual channel connections . Applications of the virtual path connections Network elements involved in the transport of user plane information Possible communication scenarios for typical configurations at the
18、user access . B-ISDN control and management transport network . General objectives and requirements Generic transport network structure Possible network architectures 4.3.1 VP cross-connect backbone . 4.3.2 VC cross-connect backbone 4.3.3 VP-VC cross-connect backbone with B-STP functionality . Perfo
19、rmance requirements Network management of the control and management transport network . Reliability requirements B-ISDN signalling principles 1.6.1 Generic definitions of the connection endpoint and Functions at the connection end-point . 1.6.2 1.6.3 Control and management of VPC andor VCC at user
20、access Communications between user and network elements . Recommendation 1.311 (08/96) Page 1 1 2 2 2 3 4 4 4 4 4 4 5 6 6 6 6 8 9 9 10 12 14 15 16 16 16 17 18 19 19 19 19 . 111 STD-ITU-T RECMN 1.3LL-ENGL 117b Lidb257L ObSL53b 5T5 9 5.1 Introduction . 5.2 Signalling capabilities . 5.2.1 5.2.2 5.2.3 O
21、thers . Capabilities to control ATM virtual channel connections and virtual path connections for information transfer . Capability to support multiparty and multiconnection calls 5.3 Signalling transport function . 5.3.1 Signalling virtual channels 5.3.2 Meta-signalling 5.3.3 Signalling configuratio
22、ns . 5.3.4 Requirements for signalling procedures Network capabilities to support charging of B-ISDN services . 6 Annex A - Hierarchical structure for ATM transport network Annex B . Network element functions and VPNC connections Annex C . Definition and scope of service profiles at user access C.l
23、Definition C.2 Scope . C.3 Service profile configuration signalling network . Appendix I - Example of a path and protocol stacks of network elements within B-ISDN Appendix II - B-ISDN management functions Page 19 20 20 20 20 21 21 22 23 24 25 27 30 32 32 32 32 33 34 iv Recommendation 1.311 (08/96) R
24、ecommendation 1.311 B-ISDN GENERAL NETWORK ASPECTS (Geneva, 1991; revised Helsinki, 1993 and in 1996) VP vc 1 Network Layering Transmission path VP 1 vc 1.1 General ATM transport network is structured as two layers, namely the ATM Layer and the Physical Layer as shown in Figure 1. ATM transport netw
25、ork ATM Layer Physical Layer Higher layer I VC level I VP level Transmission path level Digital section level I Regenerator section level Figure 1/I. 311 - Hierarchy of the ATM transport network The transport functions of the ATM layer are subdivided into two levels; the VC level and the VP level. T
26、he transport functions of the physical layer are subdivided into three levels, the transmission path level, the digital section level and the regenerator section level. The transport functions of the ATM Layer are independent of the physical layer implementation. Figure 2 shows the relationship betw
27、een the virtual channel, the virtual path and the transmission path. Figure 2D.311- Relationship between the VC, the VP and transmission path Recommendation 1.311 (OW96) 1 1.2 Figure 3 shows the hierarchical level-to-level relationship in the ATM transport network. Each level relationship includes f
28、our architectural components: - Connection end-point - Connection end-point is located at the level boundary (e.g. between VC levei and VP level), where a client is served. The client may be located in the next higher level or in the management plane. The connection end-point provides the connection
29、 termination function. Connecting point - Connecting point is inside a connection where two adjacent links come together. It is located in a level where information is routed transparently. It provides the connecting function. Connection - Connection provides capability of transferring information b
30、etween endpoints. It represents the association between endpoints together with any additional information regarding the information transfer integrity. Link - Link provides capability of transferring information transparently. A link represents the association between contiguous connecting points o
31、r between an endpoint and its contiguous connecting point. Architectural components of an ATM transport network - - - As shown in Figure 3, a connection in a specific level provides services to a link in the next higher level. Annex A contains examples of a VCC supported by a cell-based (Figure A.l)
32、 and an SDH-based (Figure A.2) ATM transport network. NOTE - The relationship and/or alignment of this Recommendation with Recommendation G.803 Architecture of transport networks based on the Synchronous Digital Hierarchy (SDH) is under study to determine the relationship between an ATM transport ne
33、twork and a layered model of the SDH-based transport network. 1.3 ATMLayer Each ATM cell contains a label in its header to explicitly identify the VC to which the cell belongs. This label consists of two parts - a Virtual Channel Identifier (VCI) and a Virtual Path Identifier (VPI). 1.3.1 Virtual ch
34、annel level A Virtual Channel (VC) is a generic term used to describe a unidirectional communication capability for the transport of ATM cells. A VCI identifies a particular VC link for a given Virtual Path Connection (VPC). A specific value of VCI is assigned each time a VC is switched in the netwo
35、rk. A VC link is a unidirectional capability for the transport of ATM cells between two consecutive ATM entities where the VCI value is translated. A VC link is originated or terminated by the assignment or removal of the VCI value. Routing functions of virtual channels are done at a VC switchkross-
36、connect?. This routing involves translation of the VCI values of the incoming VC links into the VCI values of the outgoing VC links. Virtual channel links are concatenated to form a Virtual Channel Connection (VCC). A VCC extends between two VCC endpoints or, in the case of point-to-multipoint arran
37、gements, more than two VCC endpoints. A VCC endpoint is the point where the cell information field is exchanged between the ATM Layer and the user of the ATM Layer service. See 3.1 for the definition of switch and cross-connect. 2 Recommendation 1.311 (08/96) At the VC level, VCCs are provided for t
38、he purpose of user-user, user-network, or network-network information transfer. Cell sequence integrity is preserved as defined in clause 2fi.150 by the ATM Layer for cells belonging to the same VCC. Virtual channel levei Virtual path level Transmission path level Digital section level Regenerator s
39、ection levei Virtual channel connection j Virtual channel link / / Virtuai path connection , r I 1 , , all the VC links in a bundle have the same endpoints. A VPI identifies a group of VC links, at a given reference point, that share the same VPC. A specific value of VPI is assigned each time a VP i
40、s switched in the network. A VP link is a unidirectional capability for the transport of ATM cells between two consecutive ATM entities where the VPI Recommendation 1.311 (08/96) 3 value is translated. A VP link is originated or terminated by the assignment or removal.of the VPI value. Routing funct
41、ions for VPs are performed at a VP switchkross-connect. This routing involves translation of the VPI values of the incoming VP links into the VPI values of the outgoing VP links. VP links are concatenated to form a VPC. A VPC extends between two VPC endpoints or, in the case of point-to multipoint a
42、rrangements, there are more than two VPC endpoints. A VPC endpoint is the point where the VCIs are originated, translated or terminated. At the VP level, VPCs are provided for the purpose of user-user, user-network and network-network information transfer. When VCs are switched, the VPC supporting t
43、he incoming VC links must be terminated first and a new outgoing VPC must be created. Cell sequence integrity is preserved as defined in clause 2/I. 150 by the ATM layer for cells belonging to the same VPC. Thus cell sequence integrity is preserved for each VC link within a VPC. Figure 4 contains a
44、representation of the VP and VC switching hierarchy using the modelling of Figure 1. VPI values are modified in switching blocks for VPs and VCI values are modified in switching blocks for VCs. 1.4 Physical Layer 1.4.1 Transmission path level The transmission path extends between network elements th
45、at assemble and disassemble the payload of a transmission system. Cell delineation and header error control functions are required at the end point of each transmission path. 1.4.2 Digital section level The digital section extends between network elements which assemble and disassemble a continuous
46、bit or byte stream. 1.4.3 Regenerator section level The regenerator section is a portion of a digital section. 1.5 Hierarchical level-to-level relationship Figure 3 shows the generic hierarchical level-to-level relationship in an ATM transport network. More specific examples of this relationship are
47、 shown in Annex A for the two different physical layer options. 1.6 Functions in the virtual channel level and the virtual path level to be provided at connection end- points and connecting points are defined below. Functional description of the layered network 4 Recommendation 1.311 (08196) a) Repr
48、esentation of VC and VP switching VCI 21 VCI 23 VCI 22 VCI 24 VCI 23 VCI 25 VCI 24 VCI 24 VCI 25 VCI 21 VCI 24 VCI 22 b) Representation of VP switching TI81 1280-90 Figure 4fl.311- Representation of the VP and VC switching hierarchy 1.6.1 Connection endpoint functions provide the capability of: i) i
49、i) A client could also be located in the management plane. Connecting point functions provide the capability of connecting links at the connecting point. Generic definitions of the connection endpoint and connecting point functions adapting information suitable for the client layer; and terminating the connection for providing information integrity at the connection endpoint. Recommendation 1.311 (08/96) 5 1.6.2 Functions at the connection end-point VP Connection Endpoint Functions (VP CEPF) VP CEPF of item i) in 1.6.1 is to exchange cell information field and the contents of cell he
