1、 STD-ITU-T RECMN 1.432-ENGL 1773 E 48b2572 b34287 209 I INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU I NTEG RAT E D S E RV I C ES DIG ITA L NETWORK (ISDN) ISDN USER-NETWORK INTERFACES 1.431 (03/93 PRIMARY RATE USER-NETWORK INTERFACE - LAYER I SPECIFICAT
2、ION ITU-T Recommendation 1.431 (Previously “CCITT Recommendation“) STD-ITU-T RECMN 1.43L-ENGL 1993 W 48b2591 Ob34188 145 W FOREWORD The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the International Telecom- munication Union, The ITU-T is responsible for studying tech
3、nical, 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 meets every four years, established the topics for study by the ITU-T Study Groups whic
4、h, in their turn, produce Recommendations on these topics. ITU-T Recommendation 1.431 was revised by the ITU-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),
5、 the CCITT ceased to exist as of 28 February 1993. In its place, the ITU Telecommunication Standardization Sector (ITU-T) was created as of 1 March 1993. Similarly, in this reform process, the CCIR and the IFRE! have been replaced by the Radiocommunication Sector. In order not to delay publication o
6、f this Recommendation, no change has been made in the text to references containing the acronyms “CCITT, CCIR or IFW 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
7、 telecommunication administration and a recognized 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
8、 mechanical, including photocopying and microfilm, without permission in writing from the ITU. 1 2 3 4 5 6 7 8 CONTENTS Introduction 1.1 Scope and field of application . Type of configuration . 2.1 Point-to-point 2.2 Location of interfaces . Functional characteristics . 3.1 Summary of functions (lay
9、er 1) 3.2 Interchange circuits . 3.3 Activatioddeactivation . 3.4 Operational functions Interface at 1544 kbits . 4 .i Electrical characteristics . 4.2 Frame structure . 4.3 Timing considerations . 4.4 Time slot assignment 4.5 4.6 Interface procedures 4.7 Maintenance Interface at 2048 kbit/s . 5.1 E
10、lectrical characteristics . 5.2 Frame structure . 5.3 Timing considerations . 5.4 Jitter 5.6 Output signal balance 5.8 Interface procedures 5.9 Maintenance at the interface . Connector . Interface wiring Power feeding . 8.1 Provision of power 8.2 Power Consumption 8.3 Voltage range 8.4 Protection Ji
11、tter, wander and phase transients 5.5 Tolerable longitudinal voltage 5.7 Impedance towards ground . Annex A . Time slot assignment for interfaces having only Ho-channels A.l 1544 kbits interface A.2 2048 kbits interface Annex B - Time slot assignment for 2048 kbits interfaces having an H1 1- channel
12、 . Appendix I - Pulse mask for interface at 1544 kbit/s Recommendation 1.431 (0393) Page 1 1 1 1 1 1 1 3 3 3 9 9 14 14 15 16 18 18 36 26 36 27 27 28 29 29 31 32 36 36 37 37 37 37 37 37 38 38 38 39 1 Recommendation 1.431 PRIMARY RATE USER-NETWORK INTERFACE - LAYER 1 SPECIFICATION (Malaga-Torremolinos
13、, 1984; amended at MeIbourne, 1988, and at HeIsinki, 1993) 1 Introduction This Recommendation is concerned with the layer 1 electrical, format and channel usage characteristics of the primary rate user-network interface at the S and T reference points. In this Recommendation, the term “NT” is used t
14、o indicate network terminating layer 1 aspects of NTl and NT2 functional groups, and the term “TE” is used to indicate terminal terminating layer 1 aspects of TE1, TA and NT2 functional groups, unless otherwise indicated. The terminology used in this Recommendation is contained in Recommendation 1.1
15、12. Interfaces for the 1544 kbiils primary rate and for the 2048 kbit/s primary rate are described. It has been an objective that differences between the interface specifications for the two rates be kept to a minimum. 1.1 Scope and field of application This specification is applicable to user-netwo
16、rk interfaces at 1544 kbits and 2048 kbit/s primary rates for ISDN channel arrangements as defined in Recommendation 1.4 12. 2 Type of configuration The type of configuration applies only to the layer 1 characteristics of the interface and does not imply any consrains on modes of operation at higher
17、 layers. 2.1 Point-to-point The primary rate access will support only the point-to-point configuration. Point-to-point configuration at layer 1 implies that for each direction, only one source (transmitter) and one sink (receiver) are connected to the interface. The maximum reach of the interface in
18、 the point-to-point configuration is limited by the specification for the electrical characteristics of transmitted and received pulses and the type of interconnecting cable. Some of these characteristics are defined in Recommendation G.703. 2.2 Location of interfaces The electrical characteristics
19、for both the 1544 kbits case (4.1) and the 2048 kbit/s case (5.1) apply at the interfaces I, and Ib defined in Figure 1. Examples of functional groups corresponding to TE and NT as used here are given in 4.3h.411. 3 Functional characteristics 3.1 Summary of functions (layer 1) (see Figure 2) B-chann
20、el This function provides for the bidirectional transmission of independent B-channel signals each having a bit rate of 64 kbit/s as defined in Recommendation 1.412. Ho-channel This function provides for the bidirectional transmission of independent Ho-channel signals each having a bit rate of 384 k
21、biils as defined in Recommendation 1.412. Recommendation 1.431 (03/93) 1 STD-ITU-T RECMN 1*431-ENGL 1773 m 4Bb2591 Ob34171 73T W Bit timing Octet timing Frame alignment Power feeding (see Note) Maintenance CRC procedure - NOTE - I and I, are located at the inputoutput port of the TE or $IT. c - - -
22、-b e-, Octet timing + - - - - - + - + c - - - - - -b +-+ CRC procedure Bit timing Frame alignment Power feeding (see Note) Maintenance FIGURE lA.431 Location of interfaces TE 1 D-channel64 kbis + - - - - - -+I 1 D-channel64 kbiffs CRC Cyclic redundancy check T1301970-93/DOZ NOTE - This power-feeding
23、 function is optional and, if implemented, uses a separate pau of wires in the interface cable. FIGURE 2A.431 Functional characteristics Hi-channels This function provides for the bidirectional transmission of an Hi-channel signal having a bit rate of 1536 (Hl 1) or 1920 (H12) kbit/s as defined in R
24、ecommendation 1.4 12. D-channel This function provides for the bidirectional transmission of one D-channel signal at a bit rate of 64 kbit/s as defined in Recommendation 1.412. 2 Recommendation 1.431 (03/93) Bit timing This function provides bit (signal element) timing to enable the TE or NT to reco
25、ver information from the aggregate bit stream. Octet timing This function provides 8 kHz timing towards TE or NT for the purpose of supporting an octet structure for voice coders and for other timing purposes as required. Frame alignment This function provides information to enable the TE or NT to r
26、ecover the time-division multiplexed channels. Power feeding This function provides for the capability to transfer power across the interface towards the NT1. Maintenance This function provides information concerning operational or failure conditions of the interface. The network reference configura
27、tion for maintenance activities on primary rate subscriber access is given in Recommendation 1.604. CRC (cyclic redundancy check) procedure This function provides for protection against false framing and may provide for error performance monitoring of the interface. 3.2 Interchange circuits Two inte
28、rchange circuits, one for each direction, are used for the transmission of digital signals. All the functions listed above, with the exception of power feeding and possibly maintenance, are combined into two composite digital signals, one for each direction of transmission. If power feeding via the
29、interface is provided, an additional interchange circuit is used for power feeding. The two wires of the pairs carrying the digital signal may be reversed if symmetrical wiring is provided. 3.3 Activatioddeactivation The interfaces for the primary rate user-network interface will be active at all ti
30、mes. No activation/deactivation procedures will be applied at the interface. However, to indicate the layer 1 transport capability to layer 2, the same primitive set is used as defined in Recommendation 1.430. This provides for a unique application of the layer l/layer 2 interface. The primitives PH
31、-AR, MPH-DR, MPH-DI, and MPH-II, are not required for this application and, therefore, they are not used in this Recommendation. 3.4 Operational functions In this subclause the term network is used to indicate either: - - NT1, LT and ET functional groups in case of an interface at the T reference po
32、int; or relevant parts of the NT2 functional group in case of an interface at the S reference point. The term TE (or “user side”) is used to indicate terminal terminating layer 1 aspects of TE1, TA, and NT2 functional groups. 3.4.1 Definition of signals and signal detection at the interface Signals
33、exchanged between the network and user sides under normal and fault conditions are listed in Table 1. Further information on these signals is given in 4.7.3 and 5.9.1. Recommendation 1.431 (03/93) 3 STD-ITU-T RECMN 1-431-ENGL 1773 W 4Bb257L Ob34173 502 = Name TABLE 1A.431 List of the signals Signals
34、 between the network and user sides under normal and fault conditions LOS AIS - Active associated CRC bits - CRC error information (Note 2) - Remote alarm indication (see Table 4dG.704 for 2048 kbits systems) and (16-bit sequence of eight binary ONEs and eight binary ZEROs (1 I i li i 1100000000) in
35、 the m-bits for i 544 kbits systems No received incoming signal (Loss of signal) Continuous stream of binary ONES (Recommendation M.20) Normal operational frame Operational frame with: - Active associated CRC bits - CRC error information (see Recommendation (3.704 for 2048 kbits systems, Note 1 for
36、i 544 kbit/s systems) - No defect indication I operational frame with CRC error information - E bit according to Table 4bE.704, set to binary ZERO if CRC block is received with error (2048 kbiis systems only) - Appropriate Gn bit (n = 1 to 6) in the performance report message (see Figure 7) set to b
37、inary ONE if one or more CRC block are received with error during the performance report period (1 544 kbits systems). AIS Alarm indication signal CRC Cyclic redundancy check LOS Loss of signal RAI Remote alarm indication NOTES i option 2 of Recommendation 1.604 is optional. (see 4.7.4.2) 2 for opti
38、on 2 according to Recommendation 1.604 is given in 3.4.1.2, RAI and continuous CRC error information.) In i544 kbits systems, performance report messages are conveyed by the m-bits. However, the use of the m-bits for For 1544 kbiis systems RAI and CRC-derived error performance information cannot be
39、sent simultaneously. (Solution 3.4.1.1 Definition of signals at the interface remote alarm indication (RAI): The RAI (remote alarm indication) signal indicates loss of layer 1 capability at the user-network interface. RAI propagates towards the network if layer 1 capability is lost in the direction
40、of the user, and RAI propagates toward the user if layer 1 capability is lost in the direction of the network. For 1544 kbits systems, RAI is coded as continuously repeated 16-bit sequence of eight binary ONEs and eight binary ZEROs (1 11 11 11 100000000) in the m-bits. NOTE - HDLC flag patterns (O1
41、 1 I 11 10) are transmitted in the m-bits when no signal is to be sent. For 2048 kbit/s systems, RAI is coded in bit A, i.e. bit 3 of time slot O of the operational frame which does not contain the frame alignment signal (see Table 4b/G.704): RAI present: A-bit set to binary ONE RAI not present: A-b
42、it set to binary ZERO. 4 Recommendation 1.431 (03/93) STD-ITU-T RECMN 1.431-ENGL L773 = 48b257L Ob3LiL7Li 447 H alarm indication signal (AIS): The AIS (alarm indication signal) is used to indicate loss of layer 1 capability in the ET- to-TE direction on the network side of the user-network interface
43、. A characteristic of AIS is that its presence indicates that the timing provided to the TE may not be the network clock. AIS is non-framed and coded as all binary ONES. cyclic redundancy check error report (CRC): Performance report message (see Figure 7) in the m-bits for i 544 kbits systems, and E
44、 bit (see Table 4b/G.704) in operational frame for 2048 kbits systems are used. 3.4.1.2 Signal detection algorithm Normal operational frame The detection algorithm shall be in accordance with 2.1.2/G.706 for 1544 kbits systems and 4.1.2 and 4.21G.706 for 2048 kbit/s systems. Loss of frame alignment
45、The detection algorithm shall be in accordance with 2.1.1G.706 for 1544 kbit/s systems and 4.1.1E.706 for 2048 kbits systems. Remote alarm indication (RAI) RAI is detected when both conditions occur: for 1544 kbits systems, - frame alignment condition; - reception of repeated 16-bit sequences of eig
46、ht binary ONEs and eight binary ZEROs (1 1 1 1 1 1 1 100000000) in the m-bits; for 2048 kbits systems, - frame alignment condition; - reception of one bit A containing a binary ONE. Loss of signal (LOS) The equipment shall assume “loss of signai” when the incoming signal amplitude is, for a time dur
47、ation of at least 1 ms, more than X dB below the nominal amplitude. The equipment shall react within 12 ms by issuing AIS. The value of X is 30 for 1544 kbits systems, and 20 for 2048 kbits systems. Alarm indication signal (AIS) AIS is detected in 2048 kbits systems when both conditions occur: - - l
48、oss of frame alignment condition; reception of 5 12 bit periods containing less than three binary ZEROs. An AIS defect is detected in 1544 kbits systems at the occurrence of an unframed signal with a ONEs density of at least 99.9% present for a time T, where 3 ms I T I 75 ms. An AIS defect is termin
49、ated in 1544 kbits systems within a time period T after the detection of a signal not meeting the ONEs density or the unframed signal criteria, where 3 ms 5 T I 75 ms. CRC error information CRC error information is conveyed in the performance report message in the m-bits for 1544 kbits systems, and by reception of one E bit set to binary ZERO for 2048 kbit/s systems. CRC procedures should be in accordance with Recommendations G.704 and G.706. Recommendation 1.431 (03193) 5 STD-ITU-T RECMN 1.431-ENGL 1973 m 48b2591 Ob34195 385
