1、 STD*ITU-T RECMN G.17b-ENGL L777 D 48b2571 IIb3717b T73 D INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU G.176 (04197) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS International telephone connections and circuits - Transmission p
2、lan aspects of special circuits and connections using the international telephone connection network Planning guidelines for the integration of ATM technology into networks supporting voiceband services ITU-T Recommendation G. 176 (Previously CCITT Recommendation) STD-ITU-T RECMN G.17b-ENGL 1997 486
3、2571 Ob37L77 72T = ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS General definitions General Recommendations on the transmission quality for an entire international telephone connection General characteris
4、tics of national systems forming part of international connections General characteristics of the 4-wire chain formed by the international circuits and national extension circuits General characteristics of the 4-wire chain of international circuits; international transit General characteristics of
5、international telephone circuits and national extension circuits Apparatus associated with long-distance telephone circuits Transmission plan aspects of special circuits and connections using the international telephone connection network Protection and restoration of transmission systems Software t
6、ools for transmission systems INTERNATIONAL ANALOGUE CARRIER SYSTEM TRANSMISSION SYSTEMS INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE WITH METALLIC LINES COORDINATION OF RADIOTELEPHONY AND LINE TELE
7、PHONY TRANSMISSION MEDIA CHARACTERISTICS DIGITAL TRANSMISSION SYSTEMS TERMINAL EQUIPMENTS DIGITAL NETWORKS DIGITAL SECTIONS AND DIGITAL LINE SYSTEM GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER- SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION G. 1 OO-G. 199 G. 1 OO-G. 1 O9 G.
8、1 1 O-G. 1 1 9 G. 120-G. 129 G. 130-G. 139 G. 140-G. 149 G.150-G.159 G. 160-G. 169 G .I 7-G. 179 G.180-G.189 G. 190-G. 199 G. 200-G. 299 G ,300-G. 399 G ,400-G .449 G.450-G.499 G.700-G.799 G.800-G. 899 G.900-G. 999 For further details, please refer to TU-T List of Recommendations. STD-ITU-T RECMN G-
9、17b-ENGL 1997 D 48b2591 Ob37198 8bb ITU-T RECOMMENDATION G.176 PLANNING GUIDELINES FOR THE INTEGRATION OF ATM TECHNOLOGY INTO NETWORKS SUPPORTING VOICEBAND SERVICES Summary This Recommendation provides transmission performance planning guidance to network and service planners who are responsible for
10、 the integration of ATM technology, e.g. digital processing equipment, multiplexers, and switches, into the PSTN. This Recommendation recognizes and addresses: the interconnection of other networks, e.g. Private Networks and Digital Cellular Networks, with the PSTN, and the continued need to support
11、 existing voiceband services. Source ITU-T Recommendation G.176 was prepared by ITU-T Study Group 12 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 18th of April 1997. STD-ITU-T RECMN G.17b-ENGL 1997 = 4b2571 Ob37177 7T2 m FOREWORD ITU (International Telecommunication
12、Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (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 vie
13、w to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets 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 Recommend
14、ations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. In some areas of information technology 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 “Ad
15、ministration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectua
16、l Property Right. The 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 this Recommendation, the ITU hadhad not r
17、eceived notice of intellectual property, protected 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. O ITU 1997 All rights res
18、erved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. Recommendation G.176 (04/97) 11 1 2 4 - STD-ITU-T RECMN G.17b-ENGL 1997 9 4Bb2591 Ob37200 244 = CO
19、NTENTS Page 5 6 7 7.1 7.2 7.3 7.4 7.5 8 Preamble . Scope Normative references Terms and definitions . Abbreviations . Assumed network operating configuration . ATM technology functions . ATM technology as a digital signal processing unit ATM technology as a multiplexer ATM technology as a transport
20、system ATM as a switched network function . ATM interworking function (ATM cell - PDH/SDH intenvorking function) . Planning guidelines Recommendation G.176 (04/97) 1 i 1 2 4 4 . II1 STD*ITU-T RECMN G.17b-ENGL 1777 48b2591 Ob37201 180 9 Recommendation G. 176 PLANNING GUIDELINES FOR THE INTEGRATION OF
21、 ATM TECHNOLOGY INTO NETWORKS SUPPORTING VOICEBAND SERVICES (Geneva, I99 7) 1 Preamble This Recommendation is intended to provide transmission performance planning guidance to network and service planners who are responsible for the integration of ATM technology into networks. This Recommendation as
22、sumes that ATM will always ride on a standard physical layer transmission system, e.g. SONET (Synchronous Optical NETwork), Synchronous Digital Hierarchy (SDH). The current regulatory operating environment in certain countries has made allowance for other networks to interconnect with the PSTN. Thus
23、, this Recommendation also addresses the interconnection of other networks, e.g. Private Networks and Digital Cellular Networks, with the PSTN and it is consistent with the concept that customers may provision their own terminal equipment. The information in this Recommendation is intended to provid
24、e guidance consistent with this operating environment. 2 Scope This Recommendation deals with the subject of planning the integration of ATM technology into networks. The introduction of ATM technology into the PSTN will make it more difficult to convey in a unique fashion what is meant by the term
25、“digital PSTN“ and in some instances will require an ability to uniquely reference the portion of technology within it that is ATM or non-ATM in character. To overcome this hurdle, the term “Plesiochronous Digital Hierarchy/Synchronous Digital Hierarchy (PDWSDH) oriented networks“ will be used, the
26、intention being that these networks represent the byte domain while ATM networks represent the cell domain. To work between these domains, viz. between the PDWSDH and the ATM cell domain, it is understood that an interworking function must exist and while it may physically occw in the PDH/SDH or the
27、 ATM cell-oriented hardware, it is always deemed to occur at the boundaries of the PDWSDH and ATM cell networks. A number of existing Recommendations deal with the subject of transmission impairments that affect modern telephone connections with regads to the quality of speech communications, and to
28、 some extent, data transmission in a generic sense, and are not intended to be tied to the technology used for the transmission medium. Thus, although they do not include explicit statements to say that they are intended to provide guidance on the integration of ATM technology into the PSTN, they ca
29、n and should be used for guidance, e.g. Recommendations G. 1 13, G. 1 14 and G. 13 1. Planning rules associated with the initial creation of ATM islands and planning rules for the introduction of additional ATM technology within each of these islands will be presented. 3 Normative references The fol
30、lowing 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 subject to revision; all users of this
31、 Recommendation are therefore encouraged to investigate the possibility of applying the Recommendation G. 176 (04197) 1 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 Recommendati
32、on G. 1 O 1 (1 996), The transmission plan. ITU-T Recommendation G. 1 13 (1 996), Transmission impairments. ITU-T Recommendation G. 1 14 (1 996), One-way transmission time. ITU-T Recommendation G. 122 (1 993), Influence of national systems on stability talker echo in international connections. ITU-T
33、 Recommendation G. 126 (1 993), Listener echo in telephone networks. ITU-T Recommendation G. 13 1 (1 996), Control of talker echo. CCITT Recommendation G. 132 (1 988), Attenuation distortion. ITU-T Recommendation 1.36 1 (1995), B-ISDN A TM Layer Specijkation. ITU-T Recommendation Q.5 52 (1 996), Tra
34、nsmission characteristics at 2-wire analogue interfaces of digital exchanges. ITU-T Recommendation G.7 12 (1 996), Transmission performance characteristics of pulse code modulation channels. ITU-T Recommendation 1.73 1 (1 996), Types and general characteristics of ATM equipment. ITU-T Recommendation
35、 1.732 (1 996), Functional characteristics of A TM equipment. - - - - - - - - 4 Terms and definitions This Recommendation defines the following terms: 4.1 asynchronous transfer mode (ATM): The term applied to a technology that is based on the premise that information is transported in cells. Specifi
36、cally, in this Recommendation ATM is used to apply to technology that uses Recommendation 1.361 B-ISDN ATM Layer Specification for ATM cell size and makeup, viz. 53 octets per cell with 5 octets allocated for the header and 48 octets allocated to carry payload information. Additionally, the ATM tech
37、nology is expected to be designed consistent with Recommendation 1.73 1 and operate consistent with the functional characteristics defined in Recommendation 1.732. 4.2 ATM digital signal processing function (see Figure 2): The term applied to ATM technology that operates with cell-based signals oper
38、ating over standard line rates on both the inputs and the outputs, e.g. E3 on the input and E3 on the output, and which modifies the payload contents of the cells as they pass through in some prescribed manner. This device may modifj none, some, or all of the cells that pass through it. This cell mo
39、dification is intended to change the transmission characteristics of the signals in the virtual connections, e.g. this device may perform echo cancellation or speech compression on some or all the virtual connections that pass through it. 4.3 ATM multiplexer/crossconnect (see Figure 3): The term app
40、lied to a cell-multiplexing device that operates with cell-based signals and over standard line rates on all interfaces, e.g. TI and T3, and which passes the cells received on an input to an output. The relationship between input and output, i.e. the virtual circuits routing, does not change on a pe
41、r call basis, i.e. only permanent virtual circuits are supported. This device does not allow blocking or signal compression. 4.4 ATM transport system (see Figure 4): The term applied to a transport system that is composed of a carrier system terminated by an ATM multiplexer at each end. The relation
42、ship between input and output, i.e. virtual circuits, cannot change on a per call basis, i.e. permanent virtual circuits only are supported. This device does not allow blocking or signal compression. 2 Recommendation G.176 (04/97) STD-ITU-T RECMN G-17b-ENGL 1997 m 48b2571 Ob337203 T53 W 4.5 ATM swit
43、ch (digital interfaces only) (see Figure 5): The term applied to ATM technology that operates with cell-based signals and over standard line rates on both the inputs and the outputs, e.g. T1 or El on the input and T3 or E3 on the output, and which passes the cells received on the input to the output
44、. The relationship between input and output, can change on a per call basis, i.e. switched virtual circuits must be supported and permanent virtual circuits may be supported. This device allows blocking and performs concentration. 4.6 ATM switch (analogue and digital interfaces) (see Figure 6): The
45、term applied to ATM technology that operates with analogue 2-wire interfaces and standard digital line rates on both the inputs and the outputs, e.g. T1 on the input and T3 on the output, and which passes the cells received on the input to the output. The relationship between input and output, can c
46、hange on a per call basis, i.e. switched virtual circuits must be supported and permanent virtual circuits may be supported. (For the purposes of this Recommendation it is assumed that the cell formation function associated with an analogue input is performed before the switch function OCCUTS. Howev
47、er, this definition is not intended to constrain technical implementations.) This device allows blocking and concentration. The switch function is also required to perform 2-wire to 4-wire conversion as well as A/D conversion. 4.7 ATM interworking function (with narrowband services in the PDWSDH byt
48、e-oriented domain) (see Figure 7): The term applied to a technology device that allows ATM systems, i.e. cell- oriented systems, to interwork with narrowband, byte-oriented systems. Although interworking will have to occur in both the transmission plane and the signalling plane, this Recommendation
49、will restrict itself to the transmission plane. 4.8 DS1 signal: The term used to apply to a primary rate line signal. The signal at an interface can be specified as either El or T1. 4.9 DS3 signa1:The term used to apply to a line signal operating at the 3rd level in the transmission hierarchy. The signal at an interface can be specified as either E3 or T3. 4.10 equipment impairment factor: A number allocated to a network element, in units of “eif“, that indicates the anticipated incremental level of impairment that would result when this element is inserted into a connect
