Circuit Pack Descriptions
Issue 8.0 July 2002
7-83
In the transmit direction, the LSSW circuit pack in the IN slot interfaces with up to
16 service DS3 and STS1E circuit packs, 1 protection DS3 circuit pack, and 1
protection STS1E circuit pack. If a service DS3 or STS1E circuit pack fails, the
input protection switching relays on the failed circuit pack feed each of the three
low speed signals (DS3 or EC-1) to the LSSW (IN) circuit pack. Shorting contacts
are also provided in the DS3 and STS1E circuit pack backplane connectors so
that when the circuit pack is removed, the DSX-3 or STSX-1 cables short through
to the LSSW circuit packs for routing to the protection DS3 or STS1E circuit pack.
The three low speed signals (DS3 or EC-1) are routed into a service interface
switch on the LSSW (IN) circuit pack. Each service interface switch performs a
16:1 selection of the signal needing protection and terminates the other signals.
The three low speed signals are routed through the protection interface switches
to the protection DS3 or STS1E circuit pack.
Receive Direction. 7In the receive direction, the LSSW circuit pack in the OUT slot
accepts three DS3 or EC-1 signals from the protection DS3 or STS1E circuit pack.
Each low speed signal (DS3 or EC-1) is routed through the protection interface
switches and fed into a service interface switch. Each service interface switch
performs a 1:16 selection to output the low speed signals to the output protection
switching relays on the failed DS3 or STS1E circuit pack and on to the DSX-3 or
STSX-1 panel (or equivalent).
When a service DS3 or STS1E circuit pack is reinserted in a slot, the protection
switching relays remain in the protection state until the LNCTL circuit pack
determines that the circuit pack is good.
Control Circuitry 7
The board controller circuit controls all the circuit pack activities. The board
controller circuit interfaces with the Line Controller (LNCTL) circuit pack using the
internal board controller local area network (BCLAN). The LSSW circuit pack
reports the status of the circuit pack as well as the circuit pack inventory
information (CLEI code, serial number, etc.). The status information is used by the
LNCTL circuit pack for low speed protection switching. The LSSW circuit packs
also respond to control signals from the LNCTL circuit pack; for example, low
speed protection switching control.
The LSSW circuit packs also control the protection switching relays on the service
DS3 and STS1E circuit packs. The LSSW circuit pack in the IN slot controls the
protection switching relays on the DS3 and STS1E circuit packs in slots 1A
through 4B. The LSSW circuit pack in the OUT slot controls the protection
switching relays on the DS3 and STS1E circuit packs in slots 5A through 8B.
Power Circuitry 7
The LSSW circuit pack receives two sources of −48 volts that are diode OR'd,
fused, and filtered. A modular DC-to-DC power converter produces +5 volts used
on the circuit pack.
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