AT&T DS1/DMi/ISDN-PRI Slip, Detection, Remote, Loop, Around, Network Synchronization Options

7-110	ADMINISTRATION OPTIONS AND REQUIREMENTS — SYSTEM 75
Maintenance Options or Parameters
Slip	This option enables (y) or disables (n) switching between the primary, secondary,
Detection	and internal high-accuracy clock. The decision to switch from one source to the
	other is based on an internal slip count calculation.

NOTE: Those DS1/T1 facilities that are used to provide the primary and secondary synchronization reference should be administered for slip detection

y.Typically, those other DS1/T1 spans that are used for data applications and deemed important should also be administered for slip detection. All T1-spans connecting channel banks are excluded, unless the channel bank is externally timed. Normally, DS1/T1 spans that are used exclusively for voice and which are not assigned as the primary or secondary synchronization source should be administered for slip detection n. Refer to the network synchronization diagram to determine which option to choose.

The digital switch maintains a slip count record for each DS1. The slip count is used to determine if the T1-span is experiencing errors and, if so, the severity of the errors (type alarm). Option y enables switching between the primary, secondary, or internal high-accuracy clock. If as many as 50% of those spans that are administered for slip detection are experiencing slips (with respect to the primary), then a decision is made to switch to the secondary.

	Option	y	is equivalent to a 1 in field 10 of procedure 260,
Remote	Option	y	is only used during some phases of DS1/DMI diagnostic testing. The
Loop	normal or		operational choice is n. Option n is equivalent to a 0 in field 11 of
Around	procedure		260.

Network Synchronization Options

The SYNCHRONIZATION PLAN screen is used to specify which of the two DS1/T1-spans (that were previously administered with slip detection y) is the primary reference source and which is the secondary reference source. Figure 7-56,Synchronization Plan Screen, depicts this procedure.