1、IPI 232bllL4 0006010 T i1 I Ir Page 1 E r NT Recommendation T/L 03-14 (Edinburg 1988) PRIMARY RATE USER-NETWORK INTERFACE LAYER 1 SPECIFICATION Recommendation proposed by Working Group T/WG 12 “Transmission and multiplexing” (TM) Text of Recommendation adopted by the “Telecommunications” Commission:
2、 “The European Conference of Posts and Telecommunications Administrations, 1. INTRODUCTION This Recommendation is concerned with the layer- 1 electrical, format and channel usage characteristics of the 2048 kbit/s primary rate user-network interface at the S and T reference points. Examples of funct
3、ional groups corresponding to TE and NT as used here are given in Recommendation 1.411 item 4.3. In this Recommendation, the term “NT” is used to indicate network terminating layer-1 aspects of NT 1 and NT 2 functional groups and the term “TE” is used to indicate terminal terminating layer-1 aspects
4、 of TE 1, TA and NT 2 functional groups, unless otherwise indicated. 1.1. Scope and field of application 2.2. This specification is applicable to user-network interface at 2048 kbit/s primary rate for ISDN channel arrangements as defined in Recommandation 1.412. This specification also applies to us
5、er-network inter- faces for leased lines and to user-user interfaces. Reference configurations and special requirements for these applications, in particular ISPBX interconnections, are given in Annex B to this Recommendation. Unless otherwise indicated sections 2, 3, 5, 6, 7, 8 and Annex B of CCITT
6、 Recommendation 1.431 (Blue Book) are valid for this Recommendation. However, references to section 4/1.43 1 shall be deleted. All the references to CCITT Recommendations have to be changed accordingly to the following: - 1.604 -+ T/N 46-08 - 1.451 -+ T/S 46-30 Location of interfaces The electrical
7、characteristics (see Section 4. of this Recommendation) apply to the interface points Ia and Ib of Figure 1 (T/L 03-14). 6. INTERFACE WIRING In case of symmetrical wiring, the magnitude of the characteristic impedance of the interface cables shail be 120 ohms )20% in a frequency range from 200 kHz t
8、o 1 MHz and 120 ohms -t 10% at 1 MHz. Note. To meet national standard on radiation limitation and to reduce sensitivity to impulse noise the interface wiring may require shielding For coaxial interfaces, the magnitude of the characteristic impedance of the interface cables shall be 75 ohms +5% at 10
9、24 kHz. 7.3. Feeding voltage The feeding voltage at the NT1 shall be in the range of - 32 (provisional) to - 57 volt. If one of the wires is connected to ground, then the polarity of the other wire relative to ground shall be negative. Edition of January 30, 1989 e 2326414 O006011 1 m HO - c h a n n
10、 e 1 Time slots used T/L 03-14 E Page 2 a b C d e 1-2-3 4-5-6 7-8-9 10-11-12 13-14-15 17-18-19 20-21-22 23-24-25 26-27-28 29-30-31 Annex A Time slots used Time slot assignment for interfaces having only HO-channels. The following are examples of fixed assignment of timeslots when only HO-channels ar
11、e present at the interface. Example 1 1-2-3 7-8-9 13-14-15 20-21-22 26-27-28 4-5-6 10-11-12 17-18-19 23-24-25 29-30-31 Example 2 Edition of January 30, 1 W 2326434 OOObOLi 3 WI TIL 03-14 E Page 3 Annex C APPLICATION OF THE RECOMMENDATION FOR ISPBX INTERCONNECTIONS (LEASED LINES) C. 1. INTRODUCTION T
12、he Recommendation T/L 03-14 applies to a user network interface at the S and T reference point of the configura- tion described in CCITT Recommendation 1.41 1. In T/L 03- 14 some of the functions crossing the interface are not symmetrical (e.g. timing, operation and maintenance, power feeding). For
13、instance the network side acts regarding the timing as a master, providing the network synchronous clock, while the user side in any case acts as a slave, being synchronized to the network and looping back the timing received. It has been recognized that the interface specification should also be ap
14、plied for ISPBX interconnections via the Q reference point in accordance with Recommendation T/S 46-15. Those connections do not include ISDN exchanges. From the layer-1 point of view a number of specific application alternatives/models have been identified and are described below. Applications of I
15、SPBX to ISPBX permanent connections via the ISDN (e.g; semipermanent connection using ISDN switching capabilities) are not part of the definitions and models given below. Those applications are generally covered by the user network interface specification given in this Recommendation since the ISPBX
16、 or TE is connected to the ISDN in the same way as for switched connections. Therefore the Recommendation is fully applicable without modifications. On the contrary, for the leased-line application the relationship between the two ISPBXs or ISPBX and network has to be re-defined since the master fun
17、ction allocated to the network side of the interface in ISDN may not be present in the network. This Annex describes the modifications required for ISPBX interconnection applications based on the application alternatives/models given in section C.2. O C.2. LAYER-1 MODES OF OPERATION AND JNTERFACE/AP
18、PLCATION MODELS Two modes of operation may be envisaged, point to point and point to multipoint. The point-to-point mode is defined as a connection of two ISPBXs without any handling of information channels in the link. The point-to-multipoint mode is defined as an interconnection of more than two I
19、SPBXs sharing one interface where the information channels carried in the 2 Mbit/s stream will be handled in the network. For the two modes of operation only the application of existing types of transmission equipments conveying the digital signal are considered. If equipments are used in the networ
20、k which provide particular functionality (e.g. handling of timeslot O in the network and provision of network timing) the given remarks have to be reconsidered. Ali the models show single interface applications at the ISPBX only but do not restrict the multiple-access application type in ISPBX netwo
21、rks (unique or mixed type of models or modes of operation). C.2.1. Point-to-point mode of operation Functional model: ISPBX A ISPBX -+-IB Q = Reference point lor ISPBX interconnection links. Figure C.l (T/L 03-14). Edition of January 30, 1989 E 2326414 OOObOL3 5 E T/L 03-14 E Page 4 Interface/applic
22、ation model : Interface transmission ISPBX B ISPBX A I I J I, = Interface at Q reference point. Figure C.2 (T/L 03-14). Note. Full transparent 2 Mbit/s stream between TSPBXs. Network ISPBX Digital ISPBX section/link Figure C.3 (T/L 03-14). Note, Full transparent 2 Mbit/s stream between ISPBXs, but t
23、he digital section/link may intervene in specific cases (e.g. insertion of AIS). C.2.2. Point-to-multipoint mode of operation Functional model: ISPBX Q B - I 1 ISPBX i A I Q ISPBX r L C Figure C.4 (T/L 03-14). E 2326434 0006024 7 m! r 10 I, 10. Note TIL 03-14 E Page 5 ISPBX B Interface/appication mo
24、del: I- 1 Note .I * ISPBX A l cc I Note 2 ISPBX Note . I I, I I Network I I C Figure C.5 (T/L 03-14). Note 1. The two alternatives given in Figures C.2 (T/L 03-14) and C.3 (T/L 03-14) above may be applied between ISPBX and CC. Note 2. CC stands for a configuration of a number of digital multiplex eq
25、uipments and a distribution frame or a cross connect system. Timeslot O is terminated in the CC therefore only timeslots 1 to 31 are transparent between the ISPBXs. O C.3. SPECIAL REQUIREMENTS C.3.1. Timing requirements C.3.1.1. Point-to-point mode of operation A master/slave relationship has to be
26、established between the two ISPBXs. ISPBX A ISPBX B Figure C.6 (T/L 03-14). G = Clock signal generator. GL = Clock recovery function (e.g. clock input selection or averaging in case of more than one input). The generator in ISPBX B may be used in failure conditions. In a configuration consisting of
27、more than 2 ISPBXs connected together, two clock-distribution alternatives exist: - ISPBX A acts as a master for all interconnections (star master/slave configuration as in Figure C.6 (T/L 03-14). - a clock-distribution cascade may be applied (Figure (2.7 (TIL 03-14). O ISPBX B ISPBX A ISPBX C 1 1 1
28、 I I Figure C.7 (T/L 03-14). Edition of January 30, 1989 7 E 232bllL4 OOObOL5 9 E TIL 03-14 E Page 6 C.3.1.2. Multipoint mode of operation In this mode of operation the CC must work in synchronized-operation condition to guarantee slip performance limits, This requires that the CC acts as the master
29、 clock source and all ISPBXs as slaves. ISPBX B Slave 4 -5 L ISPBX C External clock 1 I I, Figure C.8 (TjL 03-14) C.3.2. The requirements given in paragraph 4.4.2 shall be applied, but the values for Al and f2 in Figure 5 shall be changed to those given below: Tolerable jitter and wander at inputs A
30、l = 1,5 U1 f2 = 2,4 kHz C.3.3. Output jitter An ISPBX acting as a master (e.g. ISPBX A in Figure C.6 (T/L 03-14) or ISPBX B in Figure C.7 (T/L 03-14), the output jitter shall be in accordance with the limits given in paragraph 5.4.3.1 point a). An ISPBX acting as a slave (e.g. ISPBX B in Figure (2.6
31、 (T/L 03-14) or ISPBX A and C in Figure C.7 (T/L 03-14), the output jitter shall meet the limits given in paragraph 5.4.3.2. (2.4. OPERATION AND MAINTENANCE To be drafted. Edition of January 30, 1989 4 /- y 232bYL4 OOObOLb O I/ Loopback 2 T/L 03-14 E Page 7 Channel(s) Loopback Control Control Imple-
32、 Location looped back type point mechanism Application mentation Failure Layer-1 signals localization (Note 1) + (Note 2) verification In NTl as near as possible to T loopback Compiete FFS towards ET (Note 2) Optional Appendix Channel(s) looped 1. INTRODUCTION Recommendation T/N 46-08 denes loopback
33、s used in the maintenance of the subscriber installation and subscriber access, respectively. This information is repeated here to aid in understanding the layer-1 maintenance capabilities that may affect the user-network interface. Loopback Control Control Imple- type point mechanism mentation 2. C
34、HARACTERISTICS OF LOOPBACK AT THE NETWORK SIDE Loopback B. A. 3 Locations Inside the NT 2 at the network side Inside the TE In NT 2 as near as possible to ref. point S towards the T-refer. point Tableau I. 1 (T/L 03-14). Characteristics of the loopback 2 for primary-rate subscriber access. Notes. 1.
35、 These layer-I signals may not be in the frame signals. They may be line signals. 2. In the case of using existing digital transmission systems, a manual loopback may be put in place of the loopback 2; this manual loopback may be implemented between NT 2 and NT 1 and controlled by the user on demand
36、 of the network staff. Complete transp. or non-transp. (see Note to T/N 46-08) 3. CHARACTERISTICS OF LOOPBACKS FOR PRIMARY-RATE SUBSCRIBER INSTALLATIONS NT 2 Local maintenance NT 2 Layer-3 messages in D-channel or inband signal in B-channel (Note I) 30 B&D or 31B channels (Noie 2) Optional Tableau 1
37、.2 (T/L 03-14). Characteristics of loopbacks for primary-rate subscriber installations. Note. 1. Activation/deactivation of loopback 3 may be requested from a maintenance service provider (MSP). The test, however, is performed by the NT 2 Note 2. From a technical viewpoint, it is desirable that loopback 3 always be implemented (though it is not mandatory) and so the design of protocols for loopback control should include the operation of loopback 3. Edition of January 30, 1989 - L -/, - -
