DEFINITY Enterprise Communications Server Release 7
Maintenance for R7r
555-230-126 Issue 4
June 1999
Maintenance Object Repair Procedures
9-1381SNC-BD (Switch Node Clock Circuit Pack)
9
SNC-BD (Switch Node Clock Circuit
Pack)
The Switch Node Clock (SNC) TN572 circuit pac k is part of the Center Stage
Switch (CSS) configuration. It resides in a switc h node carrier that alone or with
other switch nodes make up a CSS. In a high reliability system (dup licated SPE,
simplex PNC), each SNC is duplica ted such that there are two SNCs on each
switc h nod e c arrie r. In a cri tica l reli abil ity sy stem (dup lic ated SPE and PNC),
each switch node is fully d uplicated, a nd there is one SNC on each switch nod e
carrier. SNCs are placed in slots 1 0 and 12 of the switch node c arrier.
The active SNC communicates with each c ircuit pack in the swit ch node carrier
over the serial channel bus on the b ackplane. In add ition, the active SNC
provides timing to the c ircuit packs in the switc h node carrier via the cloc k
busses. The active SNC uses Timing Priority Number (TPN) links with each
Switch Node Interface (SNI) and the other SNC to receive and distribute TPNs.
TPNs are used for setting up the correct t iming distribution for the switch node
carrier. The active SNC receives timing for the switch node carrier from each SNI
circuit pack in t he carrier and chooses the SNI with the best timing reference for
the switch node carrier timing signal the SNC puts out on the cloc k busses. The
timing reference for each SNI is derived from the fiber signal to each SNI. The
active SNC chooses the SNI to receive timing from b y choosing the SNI with the
lowest numbered TPN which means that the SNI is closest to the syste m timing
source. The active SNC also verifies that the SNI reference signal is good before
using that SNI as the timing reference for the switch nod e carrier. The active SNC
then supplies this timing o ver the clock busses on the b ackplane to all the SNI
and SNC circuit packs in the carrier. For more information on timing
synchronization including how the SNC fits into the overall synchronization
configuration, see the SYNC section.
MO Name (in
Alarm Log) Alarm
Level Initial Command to Run1
1. UU is the universal cabinet number (1 for PPN, 2 - 44 for EPNs). C is the carrier designation
(A, B, C, D, or E). SS is the number of the slot in which the circuit pack resides (10 or 12).
Full Name of MO
SNC-BD MAJOR test board UUCSS s SNC Circuit Pack
SNC-BD MINOR test board UUCSS s SNC Circuit Pack