Circuit Pack Descriptions
Issue 8.0 July 2002
7-39
High Speed Protection. 7If an OC-48 signal fails or is degraded, the LNCTL circuit
pack broadcasts a switch request to the board controllers on the DS3 circuit packs
via the BCLAN. In the transmit direction, the DS3 circuit packs perform head-end
bridges. In the FT-2000 OC-48 Add/Drop-Rings Terminal, the 155.52 Mb/s signals
are provided to the OC48 TRMTR A/D circuit packs for lines 1E and 1W at all
times. In the receive direction, the DS3 circuit packs perform tail-end switches. In
the FT-2000 OC-48 Add/Drop-Rings Terminal, selector circuitry on the DS3 circuit
packs accepts the 155.52 Mb/s signals from the OC48 RCVR A/D circuit pack
opposite of the configured direction.
Dual Ring Interworking Protection. 7The DS3 circuit pack at the primary node of a
dual ring interworking application monitors the DS3 signal(s) coming from the
other ring. If an incoming DS3 loss-of-signal condition is detected, the DS3 circuit
pack notifies the LNCTL circuit pack. The LNCTL circuit pack broadcasts an
automatic switch request to the board controller on the OC48 TRMTR circuit pack
via the BCLAN. In the add (toward to OC-48 line) direction only, the OC48 TRMTR
circuit pack switches to (selects) the standby 155.52 Mb/s signal (STS-3 tributary)
from the secondary node. In Release 7 and later releases, the OC48 TRMTR
circuit pack may switch to (select) the standby 51.84 Mb/s signal (STS-1 tributary)
from the secondary node. This completes the circuit from the secondary node to
the termination node in the ring.
Synchronization Reference Protection. 7Synchronization reference switching is
done by selecting the primary or secondary synchronization reference signal from
the TG3 (DS1) circuit packs. The DS3 circuit pack monitors these synchronization
reference signals and can autonomously select the primary or secondary. The
LNCTL circuit pack can inhibit this autonomous selection and make its own
selection.
Fault Detection Circuitry 7
Monitoring and Testing. 7The board controller circuit monitors all the activities on
the circuit pack. The DS3 circuit pack has an in-service and out-of-service built-in
test capability. In-service testing is continuous. If an error occurs, the board
controller reports the error to the LNCTL circuit pack using the board controller
local area network (BCLAN). An out-of-service test is performed whenever the
DS3 circuit pack is inserted in a slot or reset.
Loopbacks. 7The DS3 circuit pack provides one DS3 loopback for each DS3 signal.
The loopback is implemented inside the DS3/STS-1 synchronizer/desynchronizer
device. It bridges the desynchronizer output signal (transmitted towards the
DSX-3 panel) back into the DS3 synchronizer input. The loopback is implemented
in response to CIT commands (via the SYSCTL and LNCTL circuit packs) and
controlled by board controller.
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