1、CEPT T/CS*b2-03*E 2326414 0005244 8 = Page 1 (3 TCS62-03 E Recommendation T/CS 62-03 (Brussels 1980, modified in Vienna 1982, Montpellier 1984 and Odense 1986) CONNECTIONS, SIGNALLING, CONTROL, CALL HANDLING AND ANCILLARY FUNCTIONS FOR DIGITAL LOCAL AND COMBINED EXCHANGES Recommendation proposed by
2、working Group T/WG 1 1 “Switching and Signalling” (CS) “The European Conference of Postal and Telecommunications Administrations, recommends that the members of the CEPT, when introducing digital local and combined exchanges, take account of and give effect to the following specifications on Connect
3、ions, Signalling, Control, Call Handling and Ancillary Functions for digital local and combined exchanges.” The reader is referred to CCITT Recommendation 4.513 i, to which this Recommendation is identical, except for the addition and modifications indicated below. The section references (indicated
4、Q) are to 4.513 i. Q 3.1; add at the end: Note. At present, this classification does not cover connections involving either a PABX or a system independent switching unit. This is left for further study. O 0 3.4; replace by the following: Services carried in a B channel requiring less than 64 kbit/s
5、for a connection should be switched as 64 kbit/s connections. They should be presented to the exchange as 64 kbit/s channels by digital filling or by being multiplexed to a 64 kbit/s channel before entering the exchange. The process by which this is performed is not the subject of this Recommendatio
6、n. Lower bit rate channels multiplexed into a 64 kbit/s stream will be switched as a 64 kbit/s entity. Any additional services carried in the D-channel cannot be switched through the digital local exchange without special treatment and need further study. Q 3.5.1; replace the second paragraph by: In
7、 relation to the digital subscriber line (interface Vi) these connections require further study. In relation to the interface A, B, V2, V3, V4 and V5 using primary and secondary multiplex frame structures, the following should be considered. A connection of n x 64 kbit/s can seriously affect the blo
8、cking probability of an exchange and the network, particularly if all n slots are routed in a defined order in the same multiplex. The ability to handle multi-slot trafic will be influenced by the trafic loading of the exchange at any instant and the number of circuits available on the required rout
9、e. The interim requirements for a multi-slot service should be satisfied by the establishment of a number of separate semi-permanent connections which are set-up so as to preserve the time slot sequence of the multi-slot connection. A restriction on the maximum value of n or on the percentage of mul
10、ti-slot connections carried by a digital exchange is not appropriate until further studies are complete. The n slots forming a semi-permanent multi-slot connection shall all appear in the same multiplex (defined in inter- face A, B, V2, V3, V4 and VS) incoming to the exchange and shall be all switch
11、ed on the same outgoing multiplex. The channel time slots received at the output of the exchange may occur in the same frame, or the individual time slots may occur in successive frames. Note I. As this paragraph refers to a possible allocation of functions in the integrated digital network further
12、study is needed. Note 2. One possibility is for multi-slot access to be provided on the subscriber side via a number of individual 64 kbit/s accesses, each utilising interface V1. This would avoid the need for the definition of a separate subscriber side interface for multi-slot connections. This su
13、bject requires further study. O O - Edition of September 15, 1986 CEPT T/CS*b2-03*E 232b414 0005245 T TICS 62-03 E Page 2 Q 3.6.3; replace by the following; The exchange should have the capability of establishing semi-permanent connections, taking the following details into account: - Semi-permanent
14、 connections are carried within PCM multiplexes together with other connections; - They are normally not set up by subscriber control procedures; - They are normally not set up during the exchange busy hours; - They pass through the exchange switching network; - The grade of service for semi-permane
15、nt connections may differ from that of switched connections and requires Note. The supervision and re-establishment (if provided) of semi-permanent connections in the event of a failure, requires special arrangements in the exchange. 0 4.2.5; replace by the following: The signalling associated with
16、the messages/packets transported on such connections will be contained within the individual message/packet. A local or combined exchange which supports such services must contain a function that is capable of either interpreting them and routing appropriately, or of sending them directly to an appr
17、opriate interworking function. 9 4.5; add the following sections: 4.5. Signalling at interface V2 The signalling at interface V2 for system-dependent switching units is not the subject of CEPT Recommendations. 4.6 Signalling at interface V3 See T/CS 62-02 2. 4.7 Signalling at interface V4 and V5 The
18、 signalling at interface V4 is under study. Signalling at V5 may be the subject of further study. 4.8 Analogue environment On analogue subscriber lines, the digital local or combined exchange should be able to interwork with recommended CEPT signalling systems. 4.9 Signalng to other exchanges The ex
19、change should be able to interwork with other exchanges using the appropriate national, and recommended CEPT signalling systems. Within the integrated digital network, the use of CCITT Signalling System No. 7 is preferred. 4. i O Through-connection of signalling channels Signalling channels of 64 kb
20、it/s which enter the exchange via a multiplex structure may be connected through the exchange as semi-permanent connections. 4.1 1 Signalling associated with semi-permanent connections Signalling associated with semi-permanent connections is the subject of further study. further study. REFERENCES CCITT Recommendation Q.5 13. Connections, signalling, control, call handling und ancillary functions. T/CS 62-01 Recommendation. Introductionjeld of application and basic functions for digital local und combined exchanges. 11 2 Edition of September 15, 1986
