DEFINITY Enterprise Communications Server Release 7
Maintenance for R7r
555-230-126
Issue 4
June 1999
Maintenance Object Repair Procedures
9-1565SYNC (Synchronization)
9
packs in the PPN in which the TN780 resides (the external stratum 3 clock is only
allowed in the PPN). Each PPN Expansion Interface circuit pack uses the timing
generated by the TN780 to clock data from the active PPN to EPN fiber links. The
active EPN Expansion Interface circuit packs use the received data stream to
generate a timing signal which is used by the Tone-Clock circuit packs in the
EPNs to provide timing for all circuit packs in their respective EPNs. (The EPN
Tone-Clock circuit packs can be either TN780s or TN768s; only the Tone-Clock
circuit pack(s) connected to the external Stratum 3 clock must be TN780s.) The
PPN, in the above mentioned scenario, is designated the
master
port network
and the EPNs are called
slave
port networks. The
master
port network is defined
as the port network that contains the system synchronization source, the Stratum
3 clock in this case. The Stratum 4 equipment (usually a PBX) should never
provide timing to a Stratum 3 PBX.
If TDM-CLK error 2305 is in the error log, then a slave Tone-Clock loss of signal
condition exists on the slave Tone-Clock circuit pack that has this error. If only
one loss of signal occurred, the slave Tone-Clock circuit pack is receiving the
timing signal from the standby EI circuit pack (in this example, the timing is
coming from the PPN to the EPN over the standby fiber link). If another loss of
signal occurred after the Tone-clock circuit pack switched to receive timing from
the standby EI, the Tone-clock circuit pack will run on its local oscillator. The
yellow LED on the Tone-clock circuit pack flashes at the 2.7 seconds on and .3
seconds off rate (mostly on) if timing is received from an external source (an EI in
this example). Otherwise, if the Tone-clock circuit pack is running on its local
oscillator, the yellow LED flashes at the .3 seconds on and 2.7 seconds off rate
(mostly off).
Synchronization in a Center Stage Switch
Configuration
In the following typical duplicated Center Stage Switch (CSS) configuration, the
timing signal from the
master
port network, the PPN in this diagram, is sent to all
circuit packs in its network. The timing signal is sent from the Expansion Interface
(EI) circuit packs in the PPN to the Switch Node Interface (SNI) circuit packs in
the switch node carriers. The EIs in the
master
port network also sends out a
timing priority number (TPN) of 1. Every
slave
port network EI sends out a TPN of
30. The active Switch Node Clock (SNC) circuit pack in each switch node carrier
decides which SNI is providing the timing signal that the switch node carrier
should synchronize to by looking at each SNI’s incoming TPN. The SNC chooses
the SNI with the lowest numbered TPN to synchronize to. The SNC then sends
the timing signal to all SNIs and the standby SNC, if a standby SNC is present, in
the switch node carrier. The SNC also sends out a TPN equal to 1 plus the lowest
incoming TPN. Each SNI in the switch node sends the timing signal received
from the SNC and the TPN from the SNC out on its associated fiber.
If TDM-CLK error 2305 is in the error log, then a slave Tone-Clock loss of signal
condition exists on the slave Tone-Clock circuit pack that has this error. In this
case, the slave Tone-Clock circuit pack is receiving the timing signal from the
standby EI circuit pack in the port network that has the TDM-CLK 2305 error or
