џWPCL ћџ2BJ|xа АH аа АА X агга ХА6p&А6p&Х аеЮ† а Hр аааУ Уб cмˆ4 PŽТ б Fascicle VI.5 Р-Р Rec. Q.542 Ф ФPAGE1У Уб cмˆ4 PŽТ б ЮееЃ† а HH аааб cмˆ4 PŽТ бPAGE20 б cмˆ4 PŽТ бУ УFascicle VI.5 Р-Р Rec. Q.542 Ѓеа H№ ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаа X  аб cмˆ4 PŽТ бAll drawings appearing in this Recommendation have been done in Autocad. ‚У УRecommendation Q.542 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр(8Сб cмˆ4 PŽТ бDIGITAL EXCHANGE DESIGN OBJECTIVES Р-Р OPERATIONS AND MAINTENANCE аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б1ТX ТGeneralФ ФЦЦ С СThis Recommendation applies to digital local, combined, transit and international exchanges for telephony in Integrated Digital Networks (IDN) and mixed (analogue/digital) networks, and also to local, combined, transit and international exchanges in an Integrated Services Digital Network (ISDN). а H аС СThe field of application of this Recommendation is more fully defined in Recommendation Q.500. Some objectives only apply to a certain type (or types) of exchange. Where this occurs, the application is defined in the text. Where no such qualification is made, the objective applies to all exchange applications. ‚У У2ТX ТMaintenance design objectivesФ ФЦЦ а H аС СThe exchange shall be arranged so that normal maintenance activities can be easily performed by maintenance personnel. It should be capable of providing all information necessary for the identification of trouble conditions and the direction of repair activities. 2.1Тh  ТУУStatus and other informationЦЦ а H аФФС СThe exchange shall provide information to maintenance personnel so that they can quickly ascertain: Та ТР-РТ№ Тequipment/system status,ЦЦ Та ТР-РТ№ Тcritical load levels,ЦЦ Та ТР-РТ№ Тtrouble conditions,ЦЦ Та ТР-РТ№ Тnetwork management controls in effect.ЦЦ а HH а2.2Тh  ТУУInputs and outputsЦЦ а H аФФС СThe exchange shall be able to transmit and receive maintenance information and respond to commands from onР-Рsite and if appropriate, from remote maintenance centre(s) or systems over the recommended interface(s) (Recommendation Q.513). а H аС СIn performing operations and maintenance functions, the exchange shall use CCITT MML at its input/output terminals as covered in the Z.300Р-Рseries of Recommendations. 2.3Тh  ТУУRoutine testingЦЦ а H аФФС СThe exchange shall have facilities for performing or directing routine test activities on its component parts and possibly with interfacing equipment or systems. 2.4Тh  ТУУTrouble localizationЦЦ а H аФФС СThe exchange shall have adequate facilities for diagnosing and locating faults within the exchange. а H а2.5Тh  ТУУFault and alarm detection and actions at interfaces A, B, VУУ2ФФ, VУУ3ФФ and VУУ4ФФЦЦ ФФС СThe exchange shall interact with transmission systems as required to detect fault and alarms and take appropriate actions. аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТX  ТТX јТС€  СС€ HС2.5.1С јСб cмˆ4 PŽТ бУУFault detectionЦЦ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бФФС СThe following fault conditions should be detected: Та ТР-РТ№ Тfailure of local power supply (if practicable);ЦЦ Та ТР-РТ№ Тloss of incoming signal;ЦЦ а H аТа ТУУТ№ ТNoteФФ Р-Р The detection of this fault condition is required only when the fault does not result in an indication of loss of frame alignment.ЦЦ а H аТа ТР-РТ№ Тloss of frame alignment (see Recommendations G.706; the loss of frame alignment will also be assumed if no CRC multiframe alignment can be achieved or if the proportion of corrupted CRC checks exceeds a certain value);ЦЦ а H№ аТа ТР-РТ№ Тexcessive error ratio (without CRC procedure). The criteria for activating and deactivating the indication of the fault condition are given in draft Recommendation G.707. Consequent actions are given in РSР 2.5.3;ЦЦ Та ТР-РТ№ ТCRC error reporting, if applicable:ЦЦ а H аТа ТТ№ ТТhpТС€Сa)Си Сevery time a received CRC block is detected errored by the exchange termination:ЦЦ а H аТа ТТ№ ТТhpТР-РТhи Тa report will be transmitted to the error monitoring function;ЦЦ а H аТа ТТ№ ТТhpТР-РТhи Тthe information Р"Рone multiframe erroredР"Р is transmitted in the outgoing signal at the interface using an E bit (see Recommendation G.704, РSР 2.3.3.4);ЦЦ а H аТа ТТ№ ТТhpТС€Сb)Си Сevery time that an E bit in the binary state 0 is received, a report will be transmitted to the error monitoring functions.ЦЦ а H аТа ТТ№ ТТhpТ(On a provisional basis the considerations related to the E bit may only apply to V interfaces Р-Р for further study.)ЦЦ а HH ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТX  ТТX јТС€  СС€ HС2.5.2С јСб cмˆ4 PŽТ бУУAlarm signal detectionЦЦ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бФФС СThe following alarm indications should be detected: а HX аТа ТР-РТ№ ТAlarm indication (remote alarm) received from the remote end.ЦЦ а H аТа ТР-РТ№ ТAIS (alarm indication signal). The equivalent binary content of the alarm indication signal (AIS) is a continuous stream of Р"Р1Р"Рs at 2048 or 8448 kbit/s.ЦЦ а H аС СThe strategy for detecting the presence of the AIS should be such that the AIS is detectable even in the presence of an error ratio of 1 in 10б cмˆ4 PŽТ бУУ3ФФб cмˆ4 PŽТ б. However, a signal with all bits except the frame alignment bit in the 1 state should not be mistaken as an AIS. Та ТС€ HС2.5.3УУС СConsequent actionsЦЦ Та ТС€ HСФФ2.5.3.1СpСУУGeneration of alarm signals for action within the exchangeЦЦ а H аТа ТФФР-РТ№ ТThe service alarm indication should be generated to signify that the service is no longer available (see Table 1/Q.542).ЦЦ а H аТа ТР-РТ№ ТThe prompt maintenance alarm indication should be generated to signify that performance is below acceptable standards and that immediate maintenance attention is required locally (see Table 1/Q.542).ЦЦ а HH аТа ТС€ HС2.5.3.2СpСУУGeneration of alarm signals transmitted by the exchangeЦЦ а H аТа ТФФР-РТ№ ТAlarm signals sent in the outgoing direction at the exchange interface. The relevant alarm bits for the remote alarm indication, as recommended in G.704 should be effected as soon as possible (see Table 1/Q.542).ЦЦ а H аТа ТР-РТ№ ТAlarm signals sent towards the switching function. Alarm indication signal applied in all received timeР-Рslots containing speech, data and/or signalling should be applied as soon as possible and not later than 2 ms after the detection of the fault condition (see Table 1/Q.542).ЦЦ а HH аТа ТС€ HС2.5.3.3СpСУУRemoval of alarm indicationsЦЦ а H аФФС СWhen all fault conditions have been cleared and alarm indication signal is no longer received, the alarm indication signal and remote alarm indication should be removed within the same respective time limits as specified in РSР 2.5.3.4 after the conditions have cleared. ‚Ср SСб cмˆ4 PŽТ бTABLE 1/Q.542 а H аУ УFault conditions and alarms detected by exchange termination functions and consequent actions Ср MС(excluding interface VУУ1ФФ) б cмˆ4 PŽТ бФ ФвЦ‚Р@ И Р!Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH€шP Ш @ џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаааб cмˆ4 PŽТ б аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHˆxрHРpШ xа Р!џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр IСConsequent actions (see РSР 2.5.3) а И А ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџИ ˆxрHРpШ xа Р!џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа И А аб cмˆ4 PŽТ бвЦ…Р@ И аHшиˆР!Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ€шP Ш @ И џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр€LСб cмˆ4 PŽТ бFault conditions and alarm signals detected аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџИ ˆxрHџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр€PСService alarm indication generated аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџИ pиџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр€KСPrompt maintenance alarm indication generated аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџИ 0˜hџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр€MСAlarm indication to remote end generated аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџИ X Р!А"$џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр€QСAIS towards the switching stages а ˆА ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџˆX Р!А"$џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа ˆА аб cмˆ4 PŽТ бвЦ…Р@ И аHшиˆР!Цв‡а ˆx ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ€шP Ш @ ˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бFailure of power supply аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџˆxрHˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр?Р!СYes аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpиˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр?Р!СYes аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ0˜ˆhџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр?Р!ŽСYes, Ср?Р!‰Сif practicable аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџˆX Р!А"$џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр?Р!ŽСYes, Ср?Р!‰Сif practicable а ˆА аб cмˆ4 PŽТ бˆа ˆА аб cмˆ4 PŽТ бвЦ…Р@ И аHшиˆР!Цв‡а ˆx ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ€шP Ш @ ˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бLoss of incoming signal аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџˆxрHˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр?Р!СYes аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpиˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр?Р!СYes аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ0˜ˆhџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр?Р!СYes аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџˆX Р!А"$џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр?Р!СYes а ˆА аб cмˆ4 PŽТ бˆа ˆА аб cмˆ4 PŽТ бвЦ…Р@ И аHшиˆР!Цв‡а ˆр ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ€шP Ш @ ˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бLoss of frame alignment аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџˆxрHˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр?а ŒСYes Ср?а ŒСYes Ср?а ŒСYes Ср?а ŒСYes а ˆА аб cмˆ4 PŽТ бˆа ˆА аб cмˆ4 PŽТ бвЦ…Р@ И аHшиˆР!Цв‡а ˆ ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ€шP Ш @ ˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бExcessive error ratio аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџˆxрHˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр?Р!СYes Ср?Р!СYes Ср?Р!СYes Ср?Р!СYes а ˆА аб cмˆ4 PŽТ бˆа ˆА аб cмˆ4 PŽТ бвЦ…Р@ И аHшиˆР!Цв‡а ˆx ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ€шP Ш @ ˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бAlarm indication received from remote end аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџˆxрHˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬа2048 + 8448 kbit/s: Ср?Р!СYes 1544 + 6312 kbit/s: optional 1544 + 6312 kbit/s: Yes аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ0˜ˆhџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬа аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџˆX Р!А"$џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬа а ˆА аб cмˆ4 PŽТ бˆа ˆА аб cмˆ4 PŽТ бвЦ…Р@ И аHшиˆР!Цв‡а ˆа ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ€шP Ш @ ˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бAIS received аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџˆxрHˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр?X ŠСYes аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpиˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬа аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ0˜ˆhџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр?X ŠСYes Ср?X ŠСYes а ˆА аб cмˆ4 PŽТ бˆа H ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бУУNoteФФ Р-Р AУУ YesФФ in the table signifies that an action should be taken. An open space in the table signifies that the relevant action shouldУУ notФФ be taken if this condition is the only one present. If more than one fault condition or alarm is simultaneously present, action should be taken if for at least one of the conditions aУУ YesФФ is shown, except in the case of AIS received for which РSР 2.5.3.4 applies. The use of error performance monitoring in this table is for further study. аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТX  ТТX јТС€  СС€ HСб cмˆ4 PŽТ б2.5.3.4СјСб cмˆ4 PŽТ бУУAlarm processingЦЦ а H ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бФФС СThe following items are required to ensure that equipment is not removed from service due to short breaks in transmission (e.g. due to noise or transient fault) and to ensure that maintenance action does not result where no direct maintenance action is required. а H аТа ТР-РТ№ ТThe persistence of service alarm and of the prompt maintenance alarm indications may be verified for 100 ms before action is taken.ЦЦ а H аТа ТР-РТ№ ТWhen the AIS is detected, the prompt maintenance alarm indication, associated with loss of frame alignment and excessive error rate in the frame alignment pattern, should be inhibited.ЦЦ а Hр аТа ТР-РТ№ ТWhen the fault conditions cease, the service alarm and prompt maintenance alarm indications, if given, should be removed. Again, the persistence of this change in condition may be verified for 100 ms before action is taken.ЦЦ а H аТа ТР-РТ№ ТIt is possible that some systems could suffer from frequent transient faults resulting in an unacceptable quality of service. For this reason, if a persistence check is provided, fault rate monitoring should also be provided for each digital transmission system. This monitoring will result in permanent removal from service of digital transmission system which are frequently removed from the service or frequently produce transient alarm conditions. The threshold for removal from service needs study. When this action is taken the service alarm indication and the prompt maintenance alarm indication shall be given.ЦЦ а HH ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТX  ТТX јТС€  СС€ HС2.5.4С јСб cмˆ4 PŽТ бУУError performance monitoring using CRCЦЦ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТа ТС€ HСб cмˆ4 PŽТ бФФ2.5.4.1СpСУУGeneralФФЦЦ а H аС СWhen the CRC procedure is implemented at the interface, the exchange should monitor the error performance of the interface to report on the performance (see Recommendation G.821). Та ТС€ HС2.5.4.2СpСУУError performance parametersЦЦ а H аФФС СThe exchange should derive the following information from CRC checks in the incoming signal and received E bits: Та ТР-РТ№ Тdegraded minutes (DM),ЦЦ Та ТР-РТ№ Тseverely errored seconds (SES),ЦЦ Та ТР-РТ№ ТerrorР-Рfree seconds (EFS).ЦЦ а HH аС СУУNote 1ФФ Р-Р These parameters are defined in Recommendation G.821. а H аС СУУNote 2ФФ Р-Р The definition of a value for the suitable time interval during which the parameters should be assessed needs further study. а H аС СУУNote 3ФФ Р-Р The choice has to be made between the association of one type of parameter to each direction of transmission and the integration of the two directions in one type of parameter. This needs further study. С СУУNote 4ФФ Р-Р The correlation between the results of CRC checks and the parameters quoted above requires further study. Та ТС€ HС2.5.4.3СpСУУError performance evaluationЦЦ а H аФФС СEach of the performance parameters will be processed separately in order to evaluate the performance of the interface. а H аС СThe following classification of the interface maintenance conditions has to be made by the exchange (see I.600Р-Рseries of Recommendations): Та ТР-РТ№ Тcorrect functioning interface;ЦЦ Та ТР-РТ№ Тdegraded transmission interface;ЦЦ Та ТР-РТ№ Тunacceptable transmission interface.ЦЦ а Hh аС СУУNote 1ФФ Р-Р This section may only apply to V interfaces (for study). а H аС СУУNote 2ФФ Р-Р The level at which an interface for ISDN access enters the degraded transmission condition may be dependent on the quality of service provided to the customer. С СУУNote 3ФФ Р-Р The levels at which an interface enters the degraded or unacceptable transmission conditions are for further study and are outside the scope of this Recommendation. Та ТС€ HС2.5.4.4СpСУУConsequent actionsЦЦ ФФС СFor further study. 2.6Тh  ТУУFault and alarm signal detection and actions at interface VУУ1ФФЦЦ ФФС СThe exchange shall interact with transmission systems as required to detect fault and alarm signals and take appropriate actions. Та ТТ№ ТС€ Сa)СpСFault detectionС!X%СРGРЦЦ Та ТТ№ ТС€ Сb)СpСAlarm detectionС!X%СРUРС&А*СTo be specifiedЦЦ Та ТТ№ ТС€ Сc)СpСConsequent actionsС$А*СР,РЦЦ а HH а2.7Тh  ТУУFault and alarm signal detection and actions at interface ZЦЦ Та ТТ№ ТС€ СФФa)СpСFault detectionС!X%СРGРЦЦ Та ТТ№ ТС€ Сb)СpСAlarm detectionС!X%СРUРС&А*СTo be specifiedЦЦ Та ТТ№ ТС€ Сc)СpСConsequent actionsС$А*СР,РЦЦ а H а2.8Тh  ТУУFault and alarm signal detection and actions for transmission systemsЦЦ ФФС СFaults and alarms which cannot be directly detected by the exchange termination function but which are detected by transmission equipment (e.g., group pilot failure) should be accepted by the exchange as needed to take appropriate action.д Д-дŒ2.9Тh  ТУУFault and alarm signal detection and actions for channel associated signalling (2048 and 8448 kbit/s)ЦЦ Та ТС€ HСФФ2.9.1С СУУFault detectionЦЦ ФФС СThe exchange signalling function should detect the following fault conditions for each multiplex carrying a 64Р-Рkbit/s signalling channel: Та ТР-РТ№ Тfailure of local power supply (if practicable),ЦЦ Та ТР-РТ№ Тloss of 64 kbit/s incoming signal,ЦЦ а H аТа ТТ№ ТУУNoteФФ Р-Р The detection of this fault condition is required only when the fault does not result in an indication of loss of multiframe alignment.ЦЦ Та ТР-РТ№ Тloss of multiframe alignment.ЦЦ а H аС СThe criteria for activating and deactivating the indication of the fault condition are given in Recommendations G.732 and G.744. Та ТС€ HС2.9.2С СУУAlarm detectionЦЦ ФФС СThe exchange signalling function should detect the alarm indication (remote alarm) received from the remote end. Та ТС€ HС2.9.3С СУУConsequent actionsЦЦ Та ТС€ HСФФ2.9.3.1СpСУУGeneration of alarm signals for action within the exchangeЦЦ а Hx аТа ТФФР-РТ№ ТThe Service Alarm indication should be generated by the exchange signalling function to signify that the service is no longer available (see Table 2/Q.542).ЦЦ а H аТа ТР-РТ№ ТThe prompt maintenance alarm indication should be generated to signify that performance is below acceptable standards and that immediate maintenance attention is required locally (see Table 2/Q.542).ЦЦ а HH аТа ТС€ HС2.9.3.2СpСУУAlarm transmitted by the exchangeЦЦ а H аФФС СAn alarm indication (remote alarm) should be applied in the outgoing direction at the transmission/switching interface as soon as possible (see Table 2/Q.542). The relevant alarm bit for the remote alarm indication is given in Recommendation G.732. Та ТС€ HС2.9.3.3СpСУУRemoval of alarm indicationЦЦ а H аФФС СWhen all fault conditions have been cleared and AIS is no longer received, the remote alarm indication should be removed as soon as possible. Та ТС€ HС2.9.3.4СpСУУAlarm processingЦЦ ФФС СSame as in РSР 2.5.3.4. ‚Ср SСб cмˆ4 PŽТ бTABLE 2/Q.542 а H аУ УFault conditions and alarms detected by the exchange signalling function and consequent actionsФ Ф б cмˆ4 PŽТ бвЦ‚РИ Ј Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH€шP Ш И џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHhа8А`ИџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр IСConsequent actions (see РSР 2.9.3) а Ј ` ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЈ hа8А`ИџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа Ј ` аб cмˆ4 PŽТ бвЦ„РИ Ј аHpшЦв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ€шP Ш И Ј џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бFault conditions and alarms detected) аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЈ hа8џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр HСService alarm indication generated Prompt maintenance alarm indication generated Alarm indication to remote end generated а ш` ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџhа8шџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа ш` аб cмˆ4 PŽТ бвЦ„РИ Ј аHpшЦв‡а шH ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ€шP Ш И шџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бFailure of power supply аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџhа8шџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр3ˆ}СYes Ср3ˆ}СYes Ср3ˆuСYes, if practicable а ш` аб cмˆ4 PŽТ бˆа ш` аб cмˆ4 PŽТ бвЦ„РИ Ј аHpшЦв‡а ш  ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ€шP Ш И шџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бLoss of 64 kbit/s incoming signal аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџhа8шџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр3 xСYes Ср3 xСYes Ср3 xСYes а ш` аб cмˆ4 PŽТ бˆа ш` аб cмˆ4 PŽТ бвЦ„РИ Ј аHpшЦв‡а ш( ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ€шP Ш И шџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бLoss of multiframe alignment аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџhа8шџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр3˜yСYes Ср3˜yСYes Ср3˜yСYes а ш` аб cмˆ4 PŽТ бˆа ш` аб cмˆ4 PŽТ бвЦ„РИ Ј аHpшЦв‡а ш ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ€шP Ш И шџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бAlarm indication received from remote end аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџhа8шџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр3 wСYes а ш` аб cмˆ4 PŽТ бˆа  ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бУУNoteФФ Р-Р AУУ YesФФ in the table signifies that an action should be taken. An open space in the table signifies that the relevant action shouldУУ notФФ be taken if this condition is the only one present. If more than one fault condition or alarm is simultaneously present, action should be taken if for at least one of the conditions aУУ YesФФ is shown. а H ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б2.10Т№  ТУУFault and alarm signal detection and actions for channel associated channel signalling (1544 kbit/s)ЦЦ ФФС СRequires further study. а H а2.11Т№  ТУУFault and alarm signal detection and actions for common channel signallingЦЦ ФФС СRequirements specified in relevant Recommendations apply. а H а2.12Т№  ТУУFault and alarm detection and consequent actions Р-Р other functions of the exchangeЦЦ Та ТС€ HСФФ2.12.1С СУУFaulty circuitsЦЦ а H аФФС СThe exchange should not switch any new calls to a detected faulty circuit. С СThe exchange should remove from service all circuits found to be permanently faulty as detailed in РSРS 2.5, 2.8, 2.9, 2.10 and 2.11. Та ТС€ HС2.12.2С СУУMaster clock distributionЦЦ а H аФФС СThe absence of timing information distributed from a master clock located at the exchange or received from an external master clock shall be recognized and a prompt maintenance alarm shall be given. а H аС СChangeover to an alternate timing source shall be operated so as to fulfil the requirements of РSРS 2.7.2 and 2.7.3 of Recommendation Q.543. Та ТС€ HС2.12.3С СУУInternal timing distributionЦЦ ФФС СThe distribution of timing information to the major elements of the exchange shall be supervised as required. A service alarm shall be given when а H аa failure is detected. A maintenance alarm shall be given if it is appropriate. С СУУNoteФФ Р-Р Remote elements may have to be taken into consideration. 2.13Т№  ТУУSupervision or testing of interface functionЦЦ а H аФФС СThe exchange shall have the capability of verifying the proper operation of the interface functions, including the fault detection and supervision functions. а H аС СRoutine tests, statistical tests, manual activities and/or other means may be used to verify proper operation of these functions. а H аС СInformation shall be given to the far end exchange when new calls cannot be established on the circuits on which routine tests are being initiated. Established calls, including semiР-Рpermanent connections, must not be interrupted. During the tests, the generation of alarms at the far end exchange due to the removal of circuits from service should be avoided, if possible. Та ТС€ HС2.13.1С СУУET functions Р-Р Interfaces A, B, VУУ2ФФ, VУУ3ФФ and VУУ4ФФЦЦ а H аФФС СThe verification of the proper operation of exchange termination functions can be performed by the means of statistical observations or by testing. Testing may be manual or automatic. Та ТС€ HС2.13.2С СУУET functions Р-Р Interfaces C and ZЦЦ а H аТа ТТ№ ТС€ СФФi)СpСFailures of codecs (except those covered in ii) below) should be recognized by the exchange using the criteria defined in Recommendation G.732.ЦЦ а H аТа ТТ№ ТС€ Сii)СpСSupervision or testing of codecs of one or a small number of channels may be accomplished according to i) above or by interР-Рoffice transmission measurement and testing on circuits between exchanges or by statistical measurements.ЦЦ а HH аТа ТС€ HС2.13.3С СУУET functions Р-Р Interface VУУ1ФФЦЦ ФФС СTo be specified. 2.14Т№  ТУУSupervision or testing of signalling functionsЦЦ а H аФФС СIn addition to fault detection required in РSР 2.7, the following applies. Та ТС€ HС2.14.1С СУУChannel associated signallingЦЦ ФФС СThe exchange should be able to verify the proper operation of theд Д-д signalling functions by generating and responding to test calls or by a statistical observation. Та ТС€ HС2.14.2С СУУCommon channel signallingЦЦ ФФС СThe exchange should be able to verify the proper operation of the signalling functions as required by common channel signalling recommendations. 2.15Т№  ТУУSupervision or testing of exchange connectionsЦЦ ФФС СChecking the different portions of the path individually in a digital exchange network helps to ensure the continuity of the connections overall. In this respect the exchange has to verify: а Hh аТа ТР-РТ№ Тthe continuity across the exchange, as covered in this section;ЦЦ а H аТа ТР-РТ№ Тthe continuity in the transmission links terminating on the exchange as covered in РSРS 2.16 and 2.17.ЦЦ а HH аТа ТС€ HС2.15.1С СУУContinuity across the exchangeЦЦ а Hx аФФС СA means should be provided to determine that the operational error performance requirement (i.e., on bit error ratio) is being met. (The design objective for error performance can be found in Recommendation Q.554.) а H аС СThe exchange should provide adequate provision of the cross office path continuity and verify the transmission performance. (The design objective for transmission performance can be found in Recommendation Q.543.) This will guarantee, in particular, an acceptable transmission quality to its connections. Та ТС€ HС2.15.2С СУУVerification depending on the type of connectionЦЦ а H аФФС СThe verifications to be performed by the exchange should depend also on the type of connection. In particular: а Hx аТа ТР-РТ№ Тfor 64 kbit/s switched connections, the transmission performance requirements of Q.543 may be considered to be sufficient in order to guarantee the cross office path continuity;ЦЦ а H аТа ТР-РТ№ ТsemiР-Рpermanent connections may require special supervision procedures which need further study;ЦЦ а H аТа ТР-РТ№ Тsupervision of n РxР 64 kbit/s requires further study for both switched and semiР-Рpermanent connections.ЦЦ а HH а2.16Т№  ТУУSupervision or testing of digital link performanceЦЦ а H№ аФФС СThe exchange shall have the capability of monitoring digital link performance to detect when bit error ratio and loss of framing thresholds exceed operational objectives. The exchange will then take subsequent action to give appropriate trouble indications or alarms and perform other appropriate actions, such as removing circuits from service. 2.17Т№  ТУУSupervision or testing of analogue link performanceЦЦ Та ТС€ HСФФ2.17.1С СУУInterexchange circuit continuity checkЦЦ а H аФФС СThe exchange should be capable of performing circuit continuity checks in accordance with appropriate signalling system recommendations. Circuits failing circuit continuity checks should be removed from service and repair procedures initiated as required. а H аТа ТС€ HС2.17.2С СУУInterexchange transmission measurement and testing on circuits between exchangesЦЦ а H аФФС СThe exchange may also be equipped within itself or give access to external equipment to perform other transmission tests on circuits. Faulty circuits should be removed from service and repair procedures initiated as required. ‚У У3ТX ТSubscriber line maintenance and testing design objectivesФ ФЦЦ 3.1Тh  ТУУAnalogue subscriber linesЦЦ ФФС СFor further study. 3.2Тh  ТУУDigital subscriber linesЦЦ ФФС СFor further study. аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТX  ТТX јТС€  СС€ HС‚У У4С  Сб cмˆ4 PŽТ бOperations design objectivesЦЦ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бФ Ф4.1Тh  ТУУGeneralЦЦ ФФС СThe exchange and/or any associated Operations and Maintenance Systems/Centres shall have the capabilities necessary to permit it to be operated, administered, and maintained efficiently while providing service in accordance with an Administration's performance requirements. а H аС СThe Telecommunications Management Network (TMN) architecture, as described in Recommendation M.30, considers the exchange to be a Network Element (NE) which can interact with Operations Systems (OS) within a TMN. Operations systems may be used at the discretion of Administrations to improve operating efficiencies and service by centralizing and mechanizing operations, administrative and maintenance functions. The number and variety of operations systems will depend on the operating practices of the Administration. а H аС СThe decision to implement TMN principles rests with the Administration. 4.2Тh  ТУУOperations featuresЦЦ Та ТС€ HСФФ4.2.1С СУУService provisioning and recordsЦЦ ФФС СThere should be efficient means of establishing service, testing, discontinuing service and maintaining accurate records for: Та ТР-РТ№ Тsubscriber lines and services (in local exchanges);ЦЦ Та ТР-РТ№ Тinterexchange circuits.ЦЦ а HH аТа ТС€ HС4.2.2С СУУTranslation and routing informationЦЦ а H аФФС СThere should be efficient means of establishing, testing and changing call processing information, such as translation and routing information. Та ТС€ HС4.2.3С СУУResource utilizationЦЦ а H аФФС СThere should be efficient means of measuring performance and traffic flows and to arrange equipment configurations as required to insure efficient use of system resources and to provide a good grade of service to all subscribers (e.g., load balancing). Та ТС€ HС4.2.4С СУУExchange observation and measurementsЦЦ а H аФФС СThe exchange should provide means for making observations and measurements on Quality of Service and network performance, to satisfy, for example, Grade of Service objectives as covered in Recommendation E.500, or for provisioning purposes. Details of measurements for digital exchanges are given in Recommendation Q.544. 4.3Тh  ТУУExchange functions related to the TMNЦЦ а H аФФС СDetailed descriptions, definitions, and classifications of TMN functions to which the exchange will contribute is for further study. а H аС СA partial list of TMN functions is given below. A more complete list is given in Recommendation M.30. С СExchanges may have requirements for Operations, Administration and Maintenance functions which are not related to TMN. This is for further study. Та ТС€ HС4.3.1С СУУFunctions potentially related to TMNЦЦ Та ТФФР-РТ№ ТSubscriber administration;ЦЦ Та ТР-РТ№ Тtariff and charging administration;ЦЦ Та ТР-РТ№ Тrouting administration;ЦЦ Та ТР-РТ№ Тnetwork management;ЦЦ Та ТР-РТ№ Тmaintenance of subscriber lines;ЦЦ Та ТР-РТ№ Тmaintenance of circuits between exchanges;ЦЦ Та ТР-РТ№ Тexchange maintenance;ЦЦ Та ТР-РТ№ Тsignalling network maintenance;ЦЦ Та ТР-РТ№ Тadministration of hardware configuration;ЦЦ Та ТР-РТ№ Тadministration of software configuration;ЦЦ Та ТР-РТ№ Тexternal alarms and indications;ЦЦ Та ТР-РТ№ ТO&M staff procedures;ЦЦ Та ТР-РТ№ Тtraffic measurements;ЦЦ Та ТР-РТ№ Тquality of service and network performance observation.ЦЦ а HH аТа ТС€ HС4.3.2С СУУInformation flowsЦЦ а H аФФС СGenerally, information flows will consist of requests/demands to the exchange and responses from the exchange. There will also be autonomous information flows from the exchange (e.g. alarms, programmed response, etc.). Refer to Recommendation Q.513 for information on interfaces to the TMN. С СThis subject is for further study. аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТX  ТТX јТС€  СС€ HС‚У У5С  Сб cмˆ4 PŽТ бNetwork management design objectivesЦЦ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бФ Ф5.1Тh  ТУУGeneralЦЦ а H аФФС СNetwork management is the function of supervising the performance of a network and taking action to control the flow of traffic, when necessary, to promote the maximum utilization of network capacity. а H аС СThese functions have application in exchanges within the IDN, and may or may not have application in national networks during the transition period to IDN.д Д-дŒС СThe implementation of network management features and functions in national networks and in specific exchanges will be at the option of Administrations. Likewise the choice of which controls and features to use will be the option of each Administration. Та ТС€ HС5.1.1С СУУNetwork management objectivesЦЦ ФФС СInformation on network management objectives can be obtained from Recommendation E.410, and from the CCITT Р"РHandbook on Service Quality, Network Maintenance and ManagementР"Р, ITU, Geneva 1984. Та ТС€ HС5.1.2С СУУThe application of network management in exchangesЦЦ а H аФФС СIn addition to the normal engineering and economic factors, the decision whether or not to provide network management capabilities in a digital exchange will be based on the following considerations: а H аТа ТР-РТ№ Тthe size of the exchange, the size of circuit groups it serves and the network architecture;ЦЦ а H аТа ТР-РТ№ Тthe role and importance of the exchange in its own network, or as an access exchange interfacing other exchanges and networks (e.g., international or other exchange networks);ЦЦ а H аТа ТР-РТ№ Тthe requirement for the exchange to interact for network management purposes with other exchanges and/or network management centres;ЦЦ а H аТа ТР-РТ№ Тthe features necessary to provide essential services in emergency situations, where other means are not available;ЦЦ а H аТа ТР-РТ№ Тalternative approaches such as providing redundancy and special routing methods;ЦЦ а H аТа ТР-РТ№ Тthe need for managing network resources effectively when overload conditions occur in its own or interworking networks.ЦЦ Та ТТ№ ТС€ СOther factors to be considered are:ЦЦ а H№ аТа ТР-РТ№ Тthe network management organization, its equipment and selected functions;ЦЦ а H аТа ТР-РТ№ Тthe possible interactions of both the circuit switched and signalling networks when network management actions are applied under various traffic conditions or network configurations;ЦЦ а H аТа ТР-РТ№ Тthe potential impact of network management functions on the engineering design and administration of the network and the exchange;ЦЦ а Hh аТа ТР-РТ№ Тthe evolution towards IDN and interworking of SPC with nonР-РSPC exchanges in the interim period;ЦЦ а H аТа ТР-РТ№ Тthe proportion of automatic and manual features to be implemented and the rate of introduction of various network management features;ЦЦ а H аТа ТР-РТ№ Тthe reduction of exchange processing capacity due to the additional load imposed by network management (if appropriate);ЦЦ а H аТа ТР-РТ№ Тpossible additional holding time of equipment in some switching and signalling systems where open numbering is used, if and when certain network management controls are applied.ЦЦ а HH а5.2Тh  ТУУNetwork management elementsЦЦ а H аФФС СThe basic elements of a network management system to be provided by an exchange or by network management centres are: а Hh аТа ТР-РТ№ Тcollection of information about network status and performance;ЦЦ Та ТР-РТ№ Тprocessing of information for network management decisions;ЦЦ а H аТа ТР-РТ№ Тdelivery to exchanges of network status information and/or commands for control activities;ЦЦ а H аТа ТР-РТ№ Тactivation/deactivation of controls resulting from decisions made in the exchange or a network management centre;ЦЦ Та ТР-РТ№ Тfeedback of status in response to control actions.ЦЦ а H аС СDescriptions of the functions required in the exchanges to support these elements are given in РSРS 5.3 and 5.4. 5.3Тh  ТУУInformation provided by an exchange for network management purposesЦЦ Та ТС€ HСФФ5.3.1С СУУGeneralЦЦ а H аФФС СThe term Р"РinformationР"Р is used here as meaning all messages, signals or data in any form, used or provided by the exchange or by a network management centre. Та ТС€ HС5.3.2С СУУSources of informationЦЦ а H аФФС СThe information provided by an exchange for network management will be based on the status, availability and performance and configuration of: Та ТР-РТ№ Тcircuit groups;ЦЦ Та ТР-РТ№ Тexchange processes;ЦЦ Та ТР-РТ№ Тcommon channel signalling link sets;ЦЦ Та ТР-РТ№ Тother exchanges with direct links to this exchange;ЦЦ Та ТР-РТ№ Тdestination exchanges.ЦЦ а H аС СStatus information is generated by comparing the current value of load indicators with appropriate threshold values and/or detecting abnormal conditions. Such type of information assumes discrete values and it can be used, without other processing, to activate traffic control routines. С СThis information should be sent spontaneously in a realР-Рtime basis to other exchanges or to a network management centre. а H аС СPerformance information is obtained by means of traffic measurements and can be used for centralized processing or for network supervision in a network management centre. Such type of information can be sent in a nearР-РrealР-Рtime basis. а H аС СConfiguration information is used for a network management data base at exchange level. This information could include: Та ТР-РТ№ Тthreshold values actually used,ЦЦ Та ТР-РТ№ Тlist of supervised circuit groups,ЦЦ Та ТР-РТ№ Тlist of supervised signalling circuits,ЦЦ Та ТР-РТ№ Тlist of supervised processors,ЦЦ Та ТР-РТ№ Тlist of supervised destination codes,ЦЦ а H№ аТа ТР-РТ№ Тlist of primary and alternate routes for specified destinations.ЦЦ а H№ аС СDetails of network measurements are given in Recommendation Q.544. Та ТС€ HС5.3.3С СУУProcessing of network management information in an exchangeЦЦ а H аФФС СInformation collected at an exchange for network management purposes may or may not require some form of sorting and assembly (processing) before being used for network management. а H аС СWhere processing is required, this may be done by the exchange processor, or by a data processing system serving one or more exchanges, or by a network management centre. Та ТС€ HС5.3.4С СУУTransmittal of informationЦЦ а H аФФС СNetwork management information may be sent on a scheduled nearР-РrealР-Рtime basis when triggered by abnormal situations (e.g., overload conditions, alarms, etc.): alternatively, information may be sent on demand, i.e., in response to an external request. Table 3/Q.542 shows the correspondence between sources of information and their transmission mode. ‚Ср SСб cмˆ4 PŽТ бTABLE 3/Q.542 б cмˆ4 PŽТ бвЦ„(рX€И0hЦв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHј` P И 0 ˆрџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаС`p&<Сб cмˆ4 PŽТ бData transmission mode Source of information аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH(€шџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬа Ср UСRealР-Рtime Ср UСOn demand Ср UСScheduled а 0 ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ(€ш0џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа 0 аб cмˆ4 PŽТ бвЦ„(рX€И0hЦв‡а 0X ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И 0 ˆр0џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бStatus information аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ(€ш0џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр:h‡СX Ср:h‡СX а 0 аб cмˆ4 PŽТ бˆа 0 аб cмˆ4 PŽТ бвЦ„(рX€И0hЦв‡а 0 ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И 0 ˆр0џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бPerformance and availability information аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ(€ш0џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬа Ср:а ŒСX Ср:а ŒСX а 0 аб cмˆ4 PŽТ бˆа 0 аб cмˆ4 PŽТ бвЦ„(рX€И0hЦв‡а 0 ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И 0 ˆр0џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бConfiguration information аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ(€ш0џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬа Ср:а ŒСX д Д-дŒа 0 аб cмˆ4 PŽТ бˆа HH ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаС СThe destinations of network management information may be: Та ТР-РТ№ Тwithin the originating exchange,ЦЦ Та ТР-РТ№ Тto distant exchanges,ЦЦ Та ТР-РТ№ Тto a network management centre.ЦЦ а H аС СInformation may be carried by the TMN over a dedicated telemetry or data facility, over a common channel signalling network, or over other telephony network facilities as appropriate. С СFor each mode of transmittal the appropriate interface and protocol requirements, where covered by CCITT Recommendations, should be satisfied. Та ТС€ HС5.3.5С СУУPresentation of informationЦЦ а H аФФС СIndications of network management controls in effect in an exchange shall be presented on visual indicators and/or printingР-Рtype or video display terminals for purposes of advising onР-Рsite personnel. а H аС СSimilar displays and/or indicators may also be provided in a coР-Рlocated and/or distant network management centre. аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТX  ТТX јТС€  СС€ HС5.4С   Сб cмˆ4 PŽТ бУУExchange controls for network managementЦЦ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТа ТС€ HСб cмˆ4 PŽТ бФФ5.4.1С СУУGeneralЦЦ а H аФФС СNetwork management controls provide the means to alter the flow of traffic in the network, in support of network objectives. Most network management controls are applied by, or in the exchange; however, certain actions may be taken external to the exchange. Recommendation E.412 provides specific information on network management controls and gives guidance on their application. Additional information is provided in the CCITT Р"РHandbook on Service Quality, Network Management and MaintenanceР"Р. Та ТС€ HС5.4.2С СУУActivation and deactivation of controlsЦЦ а H аФФС СControls in an exchange can be activated, or deactivated, by input from a network management operations system or by direct input from an exchange manР-Рmachine interface terminal. In addition, some controls can be activated automatically either by external or internal stimulus, or by a threshold being crossed. а H аС СWhen automatic control operation is provided, means for human override should also be provided. а H аС СControls will usually be activated or deactivated in steps (stages) that are intended to avoid surge effects in the network that could be caused by too much control being added or removed too quickly. а H аС СA low level threshold may be required to remove controls as appropriate, when traffic conditions have been stabilized. Та ТС€ HС5.4.3С СУУTraffic to be controlledЦЦ ФФС СExchanges should be capable of applying a range of network management controls (see Recommendation E.412). а H аС СThe operational parameters of a control can be defined by a set of traffic attributes. As shown in Figure 1/Q.542, these parameters include distinctions based on the origin of traffic, for example, customerР-Рdialed, operatorР-Рdialed, transit or other classification as may be specified by the Administration. These can be further defined by type of service, particularly by ISDN. а H аС СAdditional attributes can be specified, for example, incoming/outgoing circuit group class, or hardР-РtoР-Рreach status of destinations can be used. Further distinctions can be based on the outgoing traffic type, for example, directР-Рrouted, alternateР-Рrouted or transit. ‚Ср KСб cмˆ4 PŽТ бFigure 1/Q.542 Љ T1107760Љ87 б cмˆ4 PŽТ б Та ТС€ HС5.4.4С СУУNetwork management controlsЦЦ ФФС СThe following is a list of typical network management controls to be considered for implementation in a given exchange. С СIt is desirable that these controls be activated to affect a variable percentage of traffic (for example, 25%, 50%, 75% or 100%). Alternatively а H аthe number of call attempts routed in a particular period may be controlled (for example 1 calls per minute). It may also be desirable to apply controls on a destination code basis. С СThese controls are normally activated/deactivated manually from a manР-Рmachine interface in the exchange, or from an operations system. The automatic operation of these controls and the need for new controls is for further study. а H аС СIt is preferable that these controls be provided in international transit exchanges and large transit exchanges in national applications. However, the decision whether or not to provide these controls in local and combined local/transit exchanges is at the discretion of the Administration. аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТX  ТТX јТС€  СС€ HС5.4.4.1СјСб cмˆ4 PŽТ бУУCode blocking controlЦЦ а H ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бФФС СThis control bars or restricts routing to a specific destination code. Code blocking can be done on a country code, an area code, an exchange identifying code and, in some cases, on an individual line number. аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТX  ТТX јТС€  СС€ HС5.4.4.2СјСб cмˆ4 PŽТ бУУCancellation of alternative routingЦЦ а H ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бФФС СThere are two types of cancellation of alternative routing control. One version prevents traffic from overflowing from the controlled route (Alternate Routed From Р-Р ARF). The other version prevents overflow traffic from all sources from having access to the controlled route (Alternate Routed To Р-Р ART). When cancellation of alternative routing is to be provided, both types are recommended. аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТX  ТТX јТС€  СС€ HС5.4.4.3СјСб cмˆ4 PŽТ бУУCall gappingЦЦ а H ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бФФС СThis control sets an upper limit on the number of call attempts allowed to be routed towards the specified destination in a particular period of time (for example, one call per minute). аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТX  ТТX јТС€  СС€ HС5.4.4.4СјСб cмˆ4 PŽТ бУУRestriction of direct routingЦЦ а H ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бФФС СThis control limits the amount of direct routed traffic accessing a route. аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТX  ТТX јТС€  СС€ HС5.4.4.5СјСб cмˆ4 PŽТ бУУSkip routeЦЦ а H ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бФФС СThis control allows traffic to bypass a specific route and advance instead to the next route in its normal routing pattern. аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТX  ТТX јТС€  СС€ HС5.4.4.6СјСб cмˆ4 PŽТ бУУTemporary alternative routingЦЦ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бФФС СThis control redirects traffic from congested routes to routes not normally available which have idle capacity at the time. This can be done for subscriber, and/or operatorР-Рoriginated traffic. аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТX  ТТX јТС€  СС€ HС5.4.4.7СјСб cмˆ4 PŽТ бУУCircuit directionalizationЦЦ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бФФС СThis control changes bothР-Рway operated circuits to oneР-Рway operated circuits. аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТX  ТТX јТС€  СС€ HС5.4.4.8СјСб cмˆ4 PŽТ бУУCircuit turndown/busyingЦЦ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бФФС СThis control removes oneР-Рway and/or bothР-Рway operated circuits from service. аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТX  ТТX јТС€  СС€ HС5.4.4.9СјСб cмˆ4 PŽТ бУУRecorded announcementsЦЦ а H ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бФФС СThese are announcements which give special instructions to operators and subscribers, such as to defer their call to a later time. аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH јP Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТX  ТТX јТС€  СС€ HС5.5С   Сб cмˆ4 PŽТ бУУAutomatic controls for network managementЦЦ аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТа ТС€ HСб cмˆ4 PŽТ бФФ5.5.1С СУУGeneralЦЦ ФФС СThis section provides descriptions of some automatic traffic control methods that can be provided in digital exchanges for network management purposes. С СAutomatic, and/or dynamic network management controls represent a significant improvement over static manual controls. These controls, which are preР-Рassigned, can respond automatically to conditions internally detected by the exchange, or to status signals from other exchanges and can be promptly removed when no longer required. С СThe following are a basic set of automatic methods for use in the telephone network: Та ТР-РТ№ ТAutomatic Congestion Control system (ACC);ЦЦ Та ТР-РТ№ ТSelective Circuit Reservation control (SCR);ЦЦ Та ТР-РТ№ ТHardР-РtoР-РReach process (HTR);ЦЦ Та ТР-РТ№ ТTemporary Trunk Blocking (TTB).ЦЦ а H аС СThe above list of methods is not exhaustive, but will provide a framework for more advanced controls which may be required in the ISDN. а H аС СIn the following four sections the typical operation of each control is described, and guidance on the application of the controls is given in РSР 5.5.6. Та ТС€ HС5.5.2С СУУAutomatic Congestion Control systemЦЦ а H аФФС СThe Automatic Congestion Control (ACC) system allows a congested exchangeд Д-д to send a congestion indicator in a backward direction to the preceding exchange. The exchange receiving the congestion indication should respond by reducing the amount of traffic offered to the congested exchange. а H аС СThe preferred method of conveying the congestion indication is via the relevant common channel signalling system. Та ТТ№ ТС€ Сa)УУСpСDetection and transmission of congestion statusЦЦ а H аТа ТФФТ№ ТAn exchange should establish a critical operating system benchmark, e.g., the time required to perform a complete basic cycle of operations. The exchange should continously monitor this benchmark and, when continued levels of nominal performance are not achieved, a state of congestion is declared. Thresholds should be established so that two levels of congestion can be identified, with congestion level 2 (C2) indicating a more severe performance degradation than congestion level 1 (C1). When either level of congestion is detected, the exchange should have the capability toЦЦ а H аТа ТТ№ ТТhpТС€С1)Си Сcode an ACC indication in the appropriate signalling messages, andЦЦ а H аТа ТТ№ ТТhpТС€С2)Си Сnotify its network management support system of its current congestion status.ЦЦ а H аТа ТТ№ ТThe ystem can offer benefit, however, by recognizing a single level of congestion. Where this situation exists, it should be regarded as congestion level 2.ЦЦ Т№ ТС€ Сb)СpСУУACC control operationЦЦ а H аТа ТФФТ№ ТExchanges receiving an ACC indication from an affected exchange or network operations centre should have the capability to institute the appropriate ACC controls and to notify its network management support system of the receipt of an ACC indication.ЦЦ а H аТа ТТ№ ТAn exchange receiving an ACC indicator from a congested exchange should activate the assigned ACC controls and start a timer. (The provisional value of the timer is five seconds and is for further study.) Subsequent received ACC indicators restart the timer, when the timer expires, the ACC controls in the exchange are removed. One or more different response categories should be available from which to choose.ЦЦ а H аТа ТТ№ ТTo avoid the incorrect application of controls, it is important that an exchange receiving an ACC indication should not reР-Рtransmit that indication to a preceding exchange.ЦЦ Та ТТ№ ТС€ Сc)СpСУУACC responseЦЦ а H аТа ТФФТ№ ТAn exchange should have the capability of assigning an ACC response category to individual circuit groups. There should be several categories available from which to choose. Each category would specify how much traffic should be controlled in response to each of the received ACC indicators. The categories should be structured so as to present a wide range of response options to received ACC indicators.ЦЦ а H аТа ТТ№ ТThe control options for further processing of calls denied access to the circuit group may be SKIP or CANCEL. The SKIP response allows a call to alternate route to the next circuit group in the routing pattern (if any) while the CANCEL response blocks the call.ЦЦ а H аТа ТТ№ ТУУNoteФФ Р-Р ACC response categories can be set locally in the exchange or by input from a network management center.ЦЦ а H аС СTable 4/Q.542 is an example of the flexibility that could be achieved in a control's response to an exchange that is experiencing congestion. а H аС СIn this example, different control actions would be taken based upon the distinction between Alternate Routed To (ART) and Direct Routed (DR) а H аtraffic types. In the future, other distinctions between traffic could be identified that would expand the number of traffic types in Table 4/Q.542. These additional traffic types could be assigned different control percentages (or excluded from ACC control, as in the case of priority calls), to give them different treatment during periods of congestion. An example would be to control hardР-РtoР-Рreach traffic as indicated in РSР 5.5.4. С СMethods used to achieve the percentages are implementation specific. Additional response categories could also be added to Table 4/Q.542 to give greater flexibility and more response options to the ACC control. ‚Ср SСб cмˆ4 PŽТ бTABLE 4/Q.542 Ср 6СУ УAn example of 2Р-Рcongestion level ACC percentage control response tableФ Ф б cмˆ4 PŽТ бвЦƒ(@ И аH0Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHј` P И џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpиP0џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр QСResponse category а H@ ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpиP0џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа H@ аб cмˆ4 PŽТ бвЦ…(@ И аHши0Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И HџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр'€YСб cмˆ4 PŽТ бCongestion level Ср'€[СTraffic type аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpиџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр'€aСA Ср'€aСB Ср'€aСC а и@ ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџpиџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа и@ аб cмˆ4 PŽТ бвЦ…(@ И аHши0Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И иџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр5ШnСб cмˆ4 PŽТ бCL1 Ср5ШnСART а ии аСр5ИoС 0 Ср5ИoС 0 Ср5ИqС100 а и@ аб cмˆ4 PŽТ бˆа и@ аб cмˆ4 PŽТ бвЦ…(@ И аH ши0Цв‡б cмˆ4 PŽТ б Ср5ШnСDR а ии а 0 Ср5ИoС 0 Ср5ИoС 0 а и@ аб cмˆ4 PŽТ бˆа и@ аб cмˆ4 PŽТ бвЦ…(@ И аHши0Цв‡Ср5ШnСб cмˆ4 PŽТ бCL2 Ср5ШnСART Ср5ШnС100 Ср5ШnС100 Ср5ШnС100 а и@ аб cмˆ4 PŽТ бˆа и@ аб cмˆ4 PŽТ бвЦ…(@ И аH ши0Цв‡б cмˆ4 PŽТ б Ср5ШnСDR а ии аСр5ИoС 0 Ср5ИpС 75 Ср5ИpС 75 а и@ аб cмˆ4 PŽТ бˆа HH ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТа Т 5.5.3Си СУУSelective Circuit Reservation controlЦЦ а H аФФС СThe Selective Circuit Reservation (SCR) Network Management control enables a digital exchange to automatically give preference to a specific type (or types) of traffic over others (e.g., direct routed calls over alternate routed calls) when circuit congestion is present or imminent. A digital exchange should provide either the single threshold of multiР-Рthreshold version of the countrol, with the latter being preferred due to its greater selectivity. Та ТС€ HС5.5.3.1СpСУУGeneral characteristicsЦЦ ФФС СA Selective Circuit Reservation control may be defined, for a given circuit group, by the following parameters: Та ТР-РТ№ Тa reservation threshold(s), andЦЦ Та ТР-РТ№ Тa control response.ЦЦ а H аС СThe reservation threshold defines how many circuits should be reserved for those traffic types to be given preferred access to the circuit group. The control response defines which traffic types should be given a lesser preference in accessing the circuit group, the quantity of each type of traffic to control, and how those calls denied access to the circuit group should be handled. Examples of possible traffic types are Direct Routed (DR), Alternate Routed To (ART), HardР-РToР-РReach (HTR), and various combinations thereof. The quantity of each type of traffic to be controlled when the threshold is exceeded may be represented by a percentage of the total traffic of that type. The control action options for further processing of calls denied access to the circuit group may be SKIP or CANCEL. а H аС СWhen the number of idle circuits in the given circuit group is less than or equal to the reservation threshold the exchange would, for that call, check the specified control response to determine if the call should be controlled. The SKIP response allows a call to alternate route to the next circuit group in the routing pattern (if any) while the CANCEL response blocks the call. а H аС СThese parameters should be able to set locally in the exchange or by input from a network management centre. In addition, the network manager should have the capability to enable and disable the control, and to enable the control but place it in a state where the control does not activate (e.g., by setting the reservation threshold to zero). Та ТС€ HС5.5.3.2СpСУУSingleР-Рthreshold Selective Circuit Reservation controlЦЦ а H аФФС СIn this version of the control, only a single reservation threshold would be available for the specified circuit group. а H аС СTable 5/Q.542 is an example of the flexibility that could be achieved in the control's response to circuit group congestion. Consider, for example, a case in which a network manager assigns response category Р"РBР"Р, a reservation threshold of 5 circuits (RT1 = 5), and a control action of SKIP to a circuit group. Then, when the control is enabled, every time the number of idle circuits in the circuit group is less than or equal to five, the exchange SKIPs 50 percent of the alternate routed traffic attempting to access the circuit group. Direct routed traffic has full access to the circuit group because the quantity of direct routed traffic to be controlled is zero percent. Note that the reservation threshold (in this example RT1 = 5) is the same for any of the response categories (A, B and C) that can be assigned to a circuit group. One or more response categories should be available from which to choose. а H аС СIn the future, other distinctions between traffic could be identified that would expand the number of traffic types in Table 5/Q.542. An example would be to control HardР-РToР-РReach traffic, as indicated in РSР 5.5.4, or to give preference to priority calls. ‚Ср SСб cмˆ4 PŽТ бTABLE 5/Q.542 а H аУ УAn example of a single threshold selective circuit reservation percentage control response tableФ Ф б cмˆ4 PŽТ бвЦƒ(P @ аH8"Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHј` P И џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б Ср LСCircuit group reservation Ср SСTraffic type аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH€pиPЈX 8"џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр DСResponse category assigned to circuit group а H8 ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH€pиPЈX 8"џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа H8 аб cмˆ4 PŽТ бвЦ…(P @ аHpш˜ˆ8"Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И HџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр'@lСб cмˆ4 PŽТ бthreshold аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH€pиџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр'@pСA Ср'@pСB Ср'@pСC а ˆ8 ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ€pиˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа ˆ8 аб cмˆ4 PŽТ бвЦ…(P @ аHpш˜ˆ8"Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И ˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр?р‡Сб cмˆ4 PŽТ бRT1 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ˜ hXаˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр?р‡СART Ср?р‡С 25 Ср?р‡С 50 Ср?р†С 100 а ˆ8 аб cмˆ4 PŽТ бˆа ˆ8 аб cмˆ4 PŽТ бвЦ…(P @ аHpш˜ˆ8"Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И ˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ˜ hXаˆџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр?р‡СDR Ср?р‡С 0 Ср?рˆС0 Ср?р‡С25 а ˆ8 аб cмˆ4 PŽТ бˆа HH ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТа Т5.5.3.3СP СУУMultiР-Рthreshold Selective Circuit Reservation controlЦЦ а H аФФС СThe multiР-Рthreshold control would support two reservation thresholds for the specified circuit group. The purpose of multiple reservation thresholds would be to allow a gradual increase in the severity of the control response as the number of idle circuits in the circuit group decreased. The only restriction on the reservation thresholds would be that a reservation threshold associated with a more stringent control must always be less than or equal to the reservation threshold of any less stringent control, in terms of the number of reserved circuits [RT2 РCР RT1 in Table 6/Q.542]. а H аС СTable 6/Q.542 is an example of the flexibility that could be achieved in the control's response to circuit group congestion with two reservation threshold control. In the future, other distinctions between traffic could be identified that would expand the number of traffic types in Table 6/Q.542, or to give preference to priority calls. ‚Ср SСб cмˆ4 PŽТ бTABLE 6/Q.542 а H аУ УAn example of a two threshold selective circuit reservation percentage control response table with HTR capabilityФ Ф б cмˆ4 PŽТ бвЦƒ(€P @ ˜Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHј` P И џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр XСб cмˆ4 PŽТ бCir Ср XСcui Ср OСt group reservation аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHи @ Ј ˜ џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр SСTraffic type аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH˜ hXH јPЈ˜џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр DСResponse category assigned to circuit group а @ и ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ@ ˜ hXH јPЈ˜џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа @ и аб cмˆ4 PŽТ бвЦ‡(€P @ ˆаHPШ˜Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P @ И џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрАQСб cмˆ4 PŽТ бthreshold аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџи @ Ј ˜ џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬа аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ@ ˜ hXџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСрАUСA СрАUСB СрАUСC СрАUСD СрАUСE а Ши ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ˜ hXШџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа Ши аб cмˆ4 PŽТ бвЦ‡(€P @ 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ˆаHPШ˜Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И ШџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б а Шш ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџи @ Ј ˜ ШџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр7ЈsСARTР-РETR Ср7ЈvС0 Ср7ЈuС25 Ср7ЈuС50 Ср7ЈuС75 Ср7ЈuС100 а Ши аб cмˆ4 PŽТ бˆа Ши аб cмˆ4 PŽТ бвЦ‡(€P @ ˆаHPШ˜Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И ШџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџи @ Ј ˜ ШџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр70qСDRР-РETR Ср70tС0 Ср70tС0 Ср70tС0 Ср70tС0 Ср70tС0 а Ши аб cмˆ4 PŽТ бˆа Ши аб cмˆ4 PŽТ бвЦ‡(€P @ ˆаHPШ˜Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И ШџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б а Шш ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџи @ Ј ˜ ШџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр7ЈsСARTР-РHTR Ср7ЈuС100 Ср7ЈuС100 Ср7ЈuС100 Ср7ЈuС100 Ср7ЈuС100 а Ши аб cмˆ4 PŽТ бˆа Ши аб cмˆ4 PŽТ бвЦ‡(€P @ ˆаHPШ˜Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И ШџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр70sСб cмˆ4 PŽТ бTR2 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџи @ Ј ˜ ШџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр70qСDRР-РHTR Ср70tС0 Ср70sС25 Ср70sС50 Ср70sС75 Ср70sС100 а Ши аб cмˆ4 PŽТ бˆа Ши аб cмˆ4 PŽТ бвЦ‡(€P @ ˆаHPШ˜Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И ШџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б а Шш ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџи @ Ј ˜ ШџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр7ЈsСARTР-РETR Ср7ЈuС50 Ср7ЈuС50 Ср7ЈuС75 Ср7ЈuС100 Ср7ЈuС100 а Ши аб cмˆ4 PŽТ бˆа Ши аб cмˆ4 PŽТ бвЦ‡(€P @ ˆаHPШ˜Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И ШџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџи @ Ј ˜ ШџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр70qСDRР-РETR Ср70tС0 Ср70tС0 Ср70sС25 Ср70sС50 Ср70sС75 а Ши аб cмˆ4 PŽТ бˆа HH ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТа Т 5.5.4Си СУУHardР-РtoР-Рreach (HTR) processЦЦ а H аФФС СThe HardР-РtoР-РReach process for network management allows exchanges to automatically make more efficient use of network resources during periods of network congestion. а H аС СPart of the improved performance of automatic controls can be derived from the ability to distinguish between destinations that are easyР-РtoР-Рreach (ETR) and destinations that are hardР-РtoР-Рreach (HTR), i.e., destinations with a low answer bid ratio, and applying heavier controls to HTR destinations. This distinction can be based on: а Hx аТа ТТ№ ТС€ Сi)СpСinternal performance measurements within the exchange/Network Management Operations System (OS) (for example, low Answer Bid Ratio (ABR) to a destination);ЦЦ Та ТТ№ ТС€ Сii)СpСsimilar information gathered by other exchanges;ЦЦ а H аТа ТТ№ ТС€ Сiii)Си Сhistorical observations of network performance by network managers.ЦЦ а H аС СThe network manager should have the ability to set the threshold for HTR determination and to assign manually a destination code as HTR. Та ТС€ HС5.5.4.1СpСУУSimplified HTR process componentsЦЦ ФФС СTo provide the fundamental elements of a simplified HTR process, the following capabilities must exist: Та ТТ№ ТС€ Сa)СpСHTR administration,ЦЦ Та ТТ№ ТС€ Сb)СpСHTR determination,ЦЦ Та ТТ№ ТС€ Сc)СpСmanually controlling calls as if hardР-РtoР-Рreach.ЦЦ а H аС СItems a) and b) may be entirely provided by the exchange or by a Network Management (OS) in cooperation with the exchange(s). Item c) can only be provided in the exchange. Та ТТ№ ТС€ Сa)СpСУУHTR administrationЦЦ а Hx аТа ТФФТ№ ТNetwork managers will administer the HTR process to optimize the information obtained about current network performance. In order to properly administer the HTR system, network managers need four capabilities. These capabilities are listed below.ЦЦ Та ТТ№ ТТhpТС€С1)Си СУУCodes to be observedЦЦ а Hр аТа ТТ№ ТФФТhpТAn exchange should automatically collect ABR data for some destination areas, e.g., countries, area codes, etc. In addition, network managers should have the capability to designate/change destinations an exchange should monitor in greater detail. An exchange should accept at least three network management designated sets of digits that identify a specific destination area and automatically begin surveillance of the specified destination areas. The specific number of digits to be analyzed is left to the discretion of the administration and may be exchange dependent.ЦЦ Та ТТ№ ТТhpТС€С2)Си СУУAdministration of HTR thresholdsЦЦ а H аТа ТТ№ ТФФТhpТThere should be a set of thresholds used to monitor destination areas and another set for use when monitoring destinations in greater detail. Network managers should be able to specify/change the values of Р"РBР"Р and Р"РTР"Р for the preР-Рestablished threshold sets and the HTR hysteresis modifiers (see b, subР-Рsection 3), below).ЦЦ Та ТТ№ ТТhpТС€С3)Си СУУAdministration of HTR determination exclusionЦЦ а H аТа ТТ№ ТФФТhpТA network manager should have the capability to exclude destination codes from being determined as HTR. This should prevent these destination codes from automatically being calculated as HTR and prevent these destination codes from being automatically placed on the Р"РHTR ControlР"Р list. A network manager should also have the ability to restore destination codes to the fully automatic HTR determination function.ЦЦ Та ТТ№ ТТhpТС€С4)Си СУУAdministrative review of HTR listЦЦ а H аТа ТТ№ ТФФТhpТNetwork managers should have the capability to view the contents of the Р"РHTR ControlР"Р list, either via a terminal at the exchange or remotely through a Network Management OS. The list should indicate which destination codes have been manually designated as HTR (see c) below). In addition, network managers should have access to a list of those destination codes which have been manually excluded from automatic HTR determination.ЦЦ Т№ Тb)Си СУУHTR determinationЦЦ Та ТФФТ№ ТThe capability should exist to determine automatically which destination codes are HTR. This is based on three capabilities.ЦЦ Та ТТ№ ТТhpТС€С1)Си СУУCode measurementsЦЦ а H аТа ТТ№ ТФФТhpТThe HTR/ETR status of a destination is based on analyzing the data for groupings of routing digits. An exchange should take measurements based on a sufficient number of routing digits to identify a destination. The exchange should take those measurements necessary to calculate the ABR for each such destination.ЦЦ Та ТТ№ ТТhpТС€С2)Си СУУHTR calculationsЦЦ Та ТТ№ ТФФТhpТPeriodically, the ABR for these destination codes under surveillance should be calculated. A recommended time interval is every 5 minutes.ЦЦ Та ТТ№ ТТhpТС€С3)Си СУУDetermining destination code HTR/ETR statusЦЦ а Hx аТа ТТ№ ТФФТhpТFor each destination code, the capacity should be provided to compare the number of bids and the calculated ABR to a set of preР-Рestablished thresholds. There should be a set of thresholds applicable to determining HTR destination areas and another set for destinations being monitored in greater detail.ЦЦ Та ТТ№ ТТhpТA set of preР-Рestablished threshold consists of:ЦЦ а H аТа ТТ№ ТТhpТР-РТhи ТB: Bids; the number of calls received by an exchange for a given destination code. This count includes calls that are successfully forwarded to the succeeding exchange as well as calls that fail within the current exchange.ЦЦ а H аТа ТТ№ ТТhpТР-РТhи ТT: ETR threshold; the threshold above which a destination code's ABR should be considered ETR.ЦЦ а Hh аТа ТТ№ ТТhpТA destination code would be considered HTR if, based on the 5Р-Рminute calculations, the measured number of bids to the code is greater than or equal to threshold Р"РBР"Р and the ABR is less than or equal to threshold Р"РTР"Р.ЦЦ а H аТа ТТ№ ТТhpТA destination code that is determined to be HTR should be placed on a Р"РHTR ControlР"Р list in the exchange.ЦЦ а H аТа ТТ№ ТТhpТTo avoid having destination codes oscillate on and off the Р"РHTR ControlР"Р list, hysteresis modifiers should be applied to determine when destination codes should be removed from the Р"РHTR ControlР"Р list. In succeeding 5Р-Рminute periods, these hysteresis modifiers should be applied to both values Р"РBР"Р and Р"РTР"Р when it is time to recalculate the HTR/ETR status of the destination code.ЦЦ а H аТа ТТ№ ТТhpТAt the beginning of each 5Р-Рminute period, the Р"РHTR ControlР"Р list should be reviewed. If a destination code that was calculated to be HTR is determined to be no longer than HTR, then it should be removed from the Р"РHTR ControlР"Р list.ЦЦ Та ТТ№ ТС€ Сc)СpСУУManually controlling calls as if HTRФФЦЦ а Hh аТа ТТ№ ТA network manager should have the capability of specifying any destination code as HTR so as to cause automatic network management control actions to take place within the exchange as indicated in РSР 5.5.4.2 below. The manually specified destination code(s) may go on the Р"РHTR ControlР"Р list. They should not, however, be subject to the 5Р-Рminute review and removal procedure described above. They should be removed upon request of a network manager. To this end, a network manager should have the capability of ending this stimulus to identifying a destination code as HTR.ЦЦ а H аТа ТТ№ ТWhenever a network manager adjusts the HTR status of a destination code, that manual action should take precedence over any automatic actions for that destination code.ЦЦ а HH аТа ТС€ HС5.5.4.2СpСУУControlling calls based on HTR statusЦЦ а H аФФС СWhen a call to a destination code that is on the Р"РHTR ControlР"Р list is being routed and a manual or automatic network management control is encountered during the processing of the call, the control should take into account the fact that the destination code is HTR. If a destination code is on the Р"РHTR ControlР"Р list, then the call should be considered HTR for all outgoing circuit groups. а H аС СAs an example of an automatic network management control incorporating HTR, the Automatic Congestion Control (ACC) Response Percentage Table а H а(Table 4/Q.542) could be expanded to apply more stringent controls to HTR traffic, as shown in Table 7/Q.542. A similar application of the Selective Circuit Reservation Control is possible (see РSР 5.5.3). ‚Ср SСб cмˆ4 PŽТ бTABLE 7/Q.542 Ср 7СУ УExample of automatic congestion control response percentages with HTRФ Ф б cмˆ4 PŽТ бвЦƒ(јpЈ №Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHј` P И џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр VСб cмˆ4 PŽТ бCongest Ср UСion level Ср SСTraffic type аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџH№XHА(€и0ˆ№џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр QСResponse category а € ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ №XHА(€и0ˆ№џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа € аб cмˆ4 PŽТ бвЦ‡(јpЈ hр( p`0 №Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ №XHАџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр^СA Ср^СB Ср^СC Ср^СD Ср^СE а € ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ№XHА џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ бˆа € аб cмˆ4 PŽТ бвЦ‡(јpЈ hр( p`0 №Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б а  аСр<}СARTР-РHTR Ср<€С0 Ср<€С0 Ср<С100 Ср<С100 Ср<С100 а € аб cмˆ4 PŽТ бˆа € аб cмˆ4 PŽТ бвЦ‡(јpЈ hр( p`0 №Цв‡Ср<ˆ}Сб cмˆ4 PŽТ бCL1 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ@ 0 ˜  џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр<ˆ{СDRР-РHTR Ср<ˆ~С0 Ср<ˆ~С0 Ср<ˆ~С0 Ср<ˆ}С100 Ср<ˆ}С100 а € аб cмˆ4 PŽТ бˆа € аб cмˆ4 PŽТ бвЦ‡(јpЈ hр( p`0 №Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б а  аСр<}СARTР-РETR Ср<€С0 Ср<€С0 Ср<€С0 Ср<€С0 Ср<€С0 а € аб cмˆ4 PŽТ бˆа € аб cмˆ4 PŽТ бвЦ‡(јpЈ hр( p`0 №Цв‡б cмˆ4 PŽТ б Ср<ˆ{СDRР-РETR Ср<ˆ~С0 Ср<ˆ~С0 Ср<ˆ~С0 Ср<ˆ~С0 Ср<ˆ~С0 а € аб cмˆ4 PŽТ бˆа € аб cмˆ4 PŽТ бвЦ‡(јpЈ hр( p`0 №Цв‡б cмˆ4 PŽТ б а  аСр<}СARTР-РHTR Ср<С100 Ср<С100 Ср<С100 Ср<С100 Ср<С100 а € аб cмˆ4 PŽТ бˆа € аб cмˆ4 PŽТ бвЦ‡(јpЈ hр( p`0 №Цв‡Ср<ˆ}Сб cмˆ4 PŽТ бCL2 аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџ@ 0 ˜  џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаСр<ˆ{СDRР-РHTR Ср<ˆ~С0 Ср<ˆ}С100 Ср<ˆ}С100 Ср<ˆ}С100 Ср<ˆ}С100 а € аб cмˆ4 PŽТ бˆа € аб cмˆ4 PŽТ бвЦ‡(јpЈ hр( p`0 №Цв‡аЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџј` P И џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаб cмˆ4 PŽТ б а  аСр<}СARTР-РETR Ср<€С0 Ср<€С0 Ср<€С0 Ср<С100 Ср<С100 а € аб cмˆ4 PŽТ бˆа € аб cмˆ4 PŽТ бвЦ‡(јpЈ hр( p`0 №Цв‡б cмˆ4 PŽТ б Ср<ˆ{СDRР-РETR Ср<ˆ~С0 Ср<ˆ~С0 Ср<ˆ~С0 Ср<ˆ~С0 Ср<ˆ}С75 а € аб cмˆ4 PŽТ бˆа HH ааЬџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџHpи P Ј XА`ИhР!(#џџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџџЬаТа Т5.5.5Си СУУTemporary Trunk BlockingЦЦ а H аФФС СTemporary Trunk Blocking (TTB) is an alternative method of exchange congestion control for application in national networks. а H аС СWhen an exchange is in a low level overload condition, a Temporary Trunk Blocking signal may be sent to a preceding exchange to indicate that the release or reР-Рoccupation of a trunk should be delayed for a short (e.g., 100 s) period of time. This may permit an overall level of up to the maximum possible load in the overloaded exchange without need to generate ACC signals. The preferred method of conveying the TTB signal is via the relevant common channel signalling system. а H аС СThe exchange receiving the Temporary Trunk Blocking signal will delay the release or the reР-Рoccupation of the concerned trunk for a short time. This time should be made changeable by operating personnel command. С СThe duration of trunk blocking is limited by a timer in the exchange receiving the Temporary Trunk Blocking signal. Therefore, an unlimited blocking of the trunk is avoided. Та ТС€ HС5.5.6С СУУApplicationЦЦ Та ТС€ HСФФ5.5.6.1СpСУУACCЦЦ ФФС СGenerally, where an Administration has introduced or is planning to introduce network management controls, it is considered appropriate for digital transit and large digital combined local/transit exchanges to be provided with full ACC capabilities. Digital local and smaller combined local/transit exchanges should only be provided with ACC receive and control capabilities. Та ТС€ HС5.5.6.2СpСУУSCRЦЦ ФФС СIt is considered appropriate for digital transit and large digital combined local/transit exchanges to be provided with a twoР-Рthreshold Selective Circuit Reservation Network Management Control. Network Management of а H аdigital local and smaller combined local/transit exchanges could benefit from having available, ideally, the two threshold or the single threshold Selective Circuit Reservation Network Management Control. The decision whether or not to provide this control in these exchanges is left to the discretion of the various Administrations. Та ТС€ HС5.5.6.3СpСУУHTRЦЦ ФФС СIt is considered appropriate for digital transit and large digital combined local/transit exchanges (optionally in conjunction with a Network Management OS) to be provided with full HTR capabilities. Digital local and smaller combined local/transit exchanges should only be provided with the manual HTR and HTR controlling (based on HTR status) capabilities, i.e., those capabilities found in РSРS 5.5.4.1 subsection c, and 5.4.4.2 of this Recommendation. It is also recommended that control modifications, based on HTR status, be added to both the ACC and Selective Circuit Reservation capabilities. Та ТС€ HС5.5.6.4СpСУУTTBЦЦ а H аФФС СIt is considered appropriate for TTB to be provided in digital transit and large digital combined local/transit exchanges in national applications. It may be particularly useful in exchanges that may not be provided with ACC capabilities, such as local exchanges. 5.6Тh  ТУУOrder of application of controlsЦЦ а H аФФС СThe order in which various network management controls shall be applied in an exchange is for further study.