ITU-T G 963-1993 Access Digital Section for ISDN Primary Rate at 1544 kbit s - Digital Sections and Digital Line Systems (Study Group XVIII) 33 pp《ISDN 基础率在1544 kbit s下用存取数字单元》.pdf

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1、CCITT RECMN*G=763 73 = Ybb259L 0577084 034 W I NTE R NAT I O N AL TE LEC OMM U N I CAT I O N U N I ON ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU DIGITAL SECTIONS AND DIGITAL LINE SYSTEMS G.963 (03/93) ACCESS DIGITAL SECTION FOR ISDN PRIMARY RATE AT 1544 kbis ITU-T Recommendation G.963 (Pr

2、eviously “CCITT Recommendation”) CCITT RECMN*G-9b3 93 +Ab2591 0577085 T70 = FOREWORD The ITU Telecommunication Standardization Sector (ITLJ-T) is a permanent organ of the Intemational Telecom- munication Union. The ITU-T is responsible for studying technical, operating and tariff questions and issui

3、ng Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on th

4、ese topics. ITLJ-T Recommendation G.963 was prepared by the ITLJ-T Study Group XVIII (1988-1993) and was approved by the WTSC (Helsinki, March 1 - 12, 1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Union (ITU), the CCITT ceased to exist as of 28 Februa

5、ry 1993. In its place, the IT Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. In order not to delay publication of this Recommendation, no change bas been ma

6、de in the text to references containing the acronyms “CCITT, CCIR, or IFRB” or their associated entities such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new ITU structure. 2 telecommunication administration and a r

7、ecognized operating agency. In this Recommendation, the expression “Administration” is used for conciseness to indicate both a O ITU 1993 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and m

8、icrofilm, without permission in writing from the ITU. CCITT RECMN*GmSb3 93 m 4862593 0577086 707 CONTENTS General 1.2 Configuration 1.3 Application . 1.4 Abbreviations Modelling and relationship between the digital section and the ET Functions . 3.1 B-channel . 3.2 HO-channel . 3.3 H 1 1 -channel .

9、3.4 D-channel . 3.5 Bit timing . 3.7 Frame alignment . 3.8 CRC procedure . 3.9 Power feeding . 3.10 Operations and maintenance . Network performance . 4.1 Availability . 4.2 Signai transfer delay . 4.3 Error performance . 4.4 Jitter . 1.1 scope 3.6 Octet timing Operations and maintenance 5.1 General

10、 . 5.2 Control facilities . 5.3 Monitoring Operation and maintenance procedures 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 General . 4 kbith data link . Partitioning of functions Definitions of signals at the T reference point . Definition of FES at the V3 reference point . PH and MPH primitives . Digital sect

11、ion (DS) state machine Definition of ET layer 1 state machine Annex A . System management requirements A.1 Introduction A.2 System management requirements Appendix I - Transmission algorithm of performance report messages at NTII based on option 2 . Page 1 1 1 2 3 3 3 3 5 5 5 5 6 6 6 6 6 6 6 6 6 7 7

12、 7 7 10 12 12 13 15 18 18 21 21 24 26 26 26 29 Recommendation G.963 (03193) 1 Recommendation G.963 ACCESS DIGITAL SECTION FOR ISDN PRIMARY RATE AT 1544 kbit/s (Helsinki, 1993) 1 General 1.1 Scope This Recommendation describes the characteristics of the primary rate access digital section at 1544 kbi

13、t/s between the user network interface (at the T reference point, defined in Recommendation 1.41 1) and the local exchange (at the V3 reference point, defined in Recommendation Q.512) supporting the 1544 kbitls primary rate interface structures defined in Recommendation 1.412 and the required additi

14、onal functions. In this Recommendation and unless otherwise indicated, the term TE is usedl to indicate terminating layer 1 aspects of TE1, TA and NT2 functional groups. When the term TE indicates terminating layer 1 aspects of El, then according to Figure 2.411, the S and T reference points coincid

15、e. The terminology used in this Recommendation is contained in Recommendatiions 1.1 12 and G.701. 1.2 Configuration Figure 1 shows the boundaries of the access digital section in relation to the digial transmission system. 1544 kbis primary rate acess digital transmission system (Note) LT reference

16、reference point point 1544 kbis primary rate access digitai section 4 TI 814670-92/d01 NOTE - The 1544 kbit/s primary rate access digital transmission system refers to either a line system using metallic media or optical fibres, or radio systems. FIGURE 1/G.963 The 1544 kbit/s primary rate access di

17、gital section and digital transmission system boundaries Recommendation 6.963 (03/93) 1 CCITT RECflN*G-qb3 93 4862571 0577088 78T = The concept of an access digitai section is used in order to allow a functional and procedural description and a definition of network requirements. NOTE - From a funct

18、ional point of view, the information transferred acrosss reference points T and V3 is different and therefore the 1544 kbit/s primary rate access digital section may not be symetrical. The concept of a digital transmission system is used in order to describe the characteristics of an implementation

19、using a specific medium in support of the access digital section. NOTE - The T and V3 reference points are defined in Recommendations 1.41 1 and Q.5 12, respectively. 1.3 Application The 1544 kbids primary rate access digital section may be applied as given in Figure 2 for: - direct access to the lo

20、cal exchange (V3 reference point); access via higher order multiplex equipment to the local exchange. - T i 544 kbiVs primary rate access digital section v3 4 b (Note I) _ V3 Digitai access link I D 1544 kbitk primary rate access digital section (Note 1 ) +- v3 NOTES 1 2 1544 kbit/s primary rate acc

21、ess digital sections may include one or more regenerators. Multiple applications of digital links and multiplexors are possible. FIGURE 2JG.963 Examples of equipment configurations in the ISDN subscriber primary rate access at 1544 kbit/s 2 Recommendation G.963 (03/93) ET CCITT RECMN*G-Sb3 93 m qBb2

22、591, 0577089 bLb 1.4 Abbreviations A number of abbreviations are used in this Recommendation, some of which are commonly used in the ISDN reference configuration while others have been created only for this Recommendation, as follows: DS (1 544 kbit/s Primary Rate) access Digital Section FE SIG Func

23、tion Element used between ET and LT SIGnal between LT and NTl DL PRM Performance Report Message 4 kbit/s Data Link (m-bits) HDLC High level Data Link Control procedures 2 Modelling and relationship between the digitai section and the ET The general model shown in Figure 3 depicts the whole ISDN cust

24、omer access layer I and adjacent entities and provides the basis to describe the functions performed by the DS and those performed by TE, ET and system management and how various functions are grouped. In particular, according to this model the maintenance functions specified in this Recommendation

25、are not confined to functions performed by the DS but include functions associated with ET layer 1. This model includes primitive procedures between ET layer 1 and ET layer 2 and between ET layer 1 and system management: - 1.43 1 to Q.920/Q.92 1 interactions between ET layer 1 and ET layer 2 and bet

26、ween ET layer I and system management based on PH and MPH primitives, respectively, as defined in Recommendation 1.431. These interactions are for the support of functions specified in Recommendations Q.920 and Q.921; - interactions between ET layer I and system management for the support of functio

27、ns associated with the DS, based on MPH primitives. The primitive procedures within TE comply with the specification according to Recommendation 1.43 1. This model does not constrain layer 1 arrangements between LT and NTl, or the primary rate access digital transmis- sion system technology. 3 Funct

28、ions For each direction of transmission of the DS the following shall be provided: - 24 time-slots at 64 kbit/s for the transport of any appropriate allocation of the following: B-, HO-, and HI I-channels; - - 1 time-slot at 64 kbit/s within 24 time-slots for the transport of a D-channel when this c

29、hannel is present; 8 kbit/s for frame alignment, and to follow the procedure for multiframe alignment, CRC, and the utilization of the m-bits, as described in Recommendations G.704 and G.706. Figure 4 shows the functions which must be supported by the DS. 3.1 B-channel This function provides for the

30、 bidirectional transmission of independent B-channel signals each having a bit rate of 64 kbith as defined in Recommendation 1.412. Recommendation G.963 (03/93) 3 CCITT RECMN*G=b3 93 m 4862593 0577070 338 m I I I I I I I I I l I II (E WN) WAS I 4 Recommendation 6.963 (03/93) CCITT RECNN*G-Sb3 93 486

31、2593 0577093 274 - B-, HO- or H1 1-channels - 1 0-channel 64 kbis (Note 1) - f-, t-, I- Bit timing - Octet timing f-, Frame alignment - - Operations - commands regarding LT, regenerator, or NT1; information from LT, regenerator, or NT1; indications of access digitai section power feeding status. 4 N

32、etwork performance 4.1 Availability The definition of availability is given in Annex NG.821. The availability objective of the DS should be consistent with the availability requirement for the hypothetical reference digitai section as given in Recommendations GA01 and 1.350. 4.2 Signai transfer dela

33、y Signal transfer delay is specified for B-channels and is defined as absolute signal delay between T and V3 reference points for each direction of transmission. The value shall be less than 2 ms when systems are implemented using metallic media, optical fibres, or a radio relay system. The applicat

34、ion of a satellite system in the DS is also possible; however, for speech services, Recommendation G. 114 may limit such an application until appropriate methods to control double satellite hops and switching of echo control devices are available. These methods are outside the scope of this Recommen

35、dation. In case of remote application of the DS (see Figure 2 with a digitai link between the DS and the ET) the signal transfer delay is defined for the DS between the T and V3 reference points. 4.3 Error performance Error performance must be consistent with the requirements given in Recommendation

36、 G.821, local grade. 6 Recommendation G.963 (03/93) 4.4 Jitter 4.4.1 Outputhput jitter at the T reference point The requirements are defined in 4.50.43 1. 4.4.2 Jitter at the V3 reference point The input jitter limits are described in Recommendation G.824. NOTE - If models described in Figure 2 are

37、used to connect a customer to the ET, jitter reduction is not required at V3. 5 Operations and maintenance 5.1 General This subclause describes the operations and maintenance functions for the DS. Further assumptions regarding system management are given in Annex A. The maintenance functions defined

38、 in Recommendation 1.604 provide the capability to maintain the DS to the level of network performance given in 4. It must be possible to test and maintain the DS in accordance with Recommendation 1.604 regardless of the subscriber installation. The main features are: a) b) control of maintenance an

39、d test support facilities; monitoring of the function elements to provide operating and performance information and fault condition indications; c) maintenance communication facility. 5.2 Control facilities 5.2.2 Loopbacks Loopbacks are maintenance tools used to assist in locating faults in the netw

40、ork. This specification covers loopback 1, 1A and 2 (see Recommendation 1.604), ail of which are complete loopbacks. Loopbacks are controlled by the codewords specified in Table 2. 5.2.1.1 Loopback implementation The various loopbacks are summarized below, and illustrated in Figure 5. 1) 2) 3) Loopb

41、ack 1 is located within the LT. It loops the 1544 kbit/s signal back to the ET. Loopback 1A is located within the regenerator. It loops the 1544 kbit/s signal back to the ET. Loopback 2 is located within the NTl and loops the 1544 kbit/s signai (line loopback) or 1536 kbit/s signal (payload loopback

42、) back to the ET. Loopback 2 may be implemented as a line loopback or as a payload loopback depending on whether the NTl terminates framing. NOTE - Line loopback shall result in a full 1544 kbit/s loopback back to the interface of the received bit stream. Bit sequence integrity shall be maintained.

43、A payload loopback is implemented only in equipment that terminates framing of the primary rate access line. The signai looped back to the received signal is 1536 kbit/s. The framing bits are originated at the loopback point The payload loopback shall maintain bit sequence integrity for the informat

44、ion bits; however, the payload loopback need not maintain the integrity of eigbt-bit time slots, frames, or multi-frames. Recommendation 6.963 (03D3) 7 I TE I r-i I I AIS I n I I I I I I I I I I L-l b FZGURE 5/G.963 Loopbacks associated with the 1544 kbit/s access digital section Access digital sect

45、ion 4 b 1 I I I I I I I r-i NTl I REG I LT I ET I 4 I AIS - c 1 AIS - c 1 AIS - c I l I I I I I I I I I L-_I Loopback2 I Loopback 1A I Loopback 1 I I 5.2.1.2 Loopback procedure The loopback control conforms with Recommendation 1.604. A normal call Set-up request cannot override a request for loopbac

46、k 1, 1 A or 2. A sequence for the loopback procedure when controlled by the ET system management is: a) b) c) ET performs the test; d) e) ET generates an operation command for the required loopback; ET receives loopback operation acknowledgement; ET generates a release command; ET receives a loopbac

47、k release indication. Activation of loopback shall be a two step process, as follows: 1) ET issues a loopback activate code 10 times in 160 consecutive m-bit positions; 2) the requested loopback is activated when the loopback activate code is detected at least 5 times and is no longer detected. This

48、 procedure is applicable to options 1, 2 and 4 defined in Recommendation 1.604. Refer to Figures 6, 7 and 8 for description to the options 1,4 and 2, respectively. Whenever a loopback is activated, AIS shall be sent forward as a replacement for the looped signal. Loopbacks shall be deactivated upon

49、receipt of any one (or combination) of the following: 1) The loopback deactivate codeword; 2) AIS; 3) a data link message consisting of two occurrences of the one-per-second PRM separated by uninterrupted idle code. 8 Recommendation 6.963 (03193) TE I II I I I I I I I I I I b) the transmission performance; c) the power feed status (optional). 5.3.2 5.3.2.1 Anomaly and defect conditions The DS shall detect the following anomalies or defects: From the user side and the exchange side of the DS: Anomaly and defect conditions and consequ