1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 - TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU-!).4%.!.#% G0G0#/-/.G0G0#(!%,G0G03).!,).3934%-342!.3b) the maintenance of the transfer link between two centres, from the output of one data modem to the inputof another data modem. This link does not includ
2、e data modems.4.2 By agreement between Administrations, one terminal international centre, or an equivalent point specified bythe Administration concerned, will be designated as the overall maintenance control station. This station will maintainan overview of the performance of Signalling System No.
3、 6 and in general be responsible to ensure that actions arecoordinated when responsibility for a particular fault is not clearly identified. Additionally, one terminal internationalcentre should function as the control station for transfer link maintenance activities.Note For a signalling system thi
4、s role may be combined with that of overall maintenance control.4.3 Organizational points or stations need to be assigned to provide for the following functions:a) Overall signalling system maintenancei) control stationii) sub-control stationiii) fault report pointiv) testing pointb) Transfer link m
5、aintenancei) control stationFascicle IV.1 - Rec. M.760 3ii) sub-control stationiii) fault report pointiv) transmission maintenance point (international line) (TMP-IL)These may be assigned by an Administration as best suited to its individual needs.It is essential that the appropriate contact point i
6、nformation be exchanged in order to minimize maintenancedifficulties. Figure B-1/M.93 offers a plan for the exchange of contact point information for the international telephoneservice and allows for the exchange of contact point information Signalling System No. 6 maintenance.4.4 This Recommendatio
7、n relates to the maintenance of the transfer link. However, maintenance activities on thetransfer link should be controlled in order to preclude interruption of signalling functions, either during normal serviceor while tests initiated by the overall maintenance control station are being carried out
8、 Furthermore, the TMP-IL forthe transfer link is not likely to be aware of any faults in the signalling system unless advised by the overall signallingmaintenance control station or transfer link control station. Therefore, testing of the transfer link will not be undertakenuntil advice (or concurr
9、ence) is received from the overall maintenance control station or the transfer link controlstation.4.5 Once a fault is indicated in Signalling System No. 6, a possible series of events is illustrated in Figure 2/M.760.In the presentation of the flowchart it has been necessary to assume a possible or
10、ganizational arrangement andassignment of responsibilities see 4.1, a) above.This chart does not go into all possibilities. It is intended to depict a process toward fault correction, lookingfirst at the most likely causes of faults in the transfer link with speedy correction in mind, and then towar
11、d moredetailed and time- consuming tests to discover more elusive faults. It should be noted that some long-term testing maybe required in this latter process.4Fascicle IV.1 - Rec. M.760Fascicle IV.1 - Rec. M.760 5References1 CCITT Recommendation Testing and maintenance Overall tests of Signalling System No. 6, Vol. VI,Rec. Q.295.2 CCITT Recommendation Reserve facilities provided, Vol. VI, Rec. Q.292.
