Circuit Pack Descriptions
Issue 8.0 July 2002
7-81
General Description of Operation 7
The signal flow through the LSSW circuit pack may be in either direction,
depending on the slot location. When the LSSW circuit pack is placed in the IN
slot on the Low Speed Shelf - System Controller or Low Speed Shelf -
Complementary, it provides a low speed protection bus in the transmit direction.
When the LSSW circuit pack is placed in the OUT slot on the Low Speed Shelf -
System Controller or Low Speed Shelf - Complementary, it provides a low speed
protection bus in the receive direction.
Each LSSW circuit pack interfaces with up to 16 service DS3 and STS1E circuit
packs, one protection DS3 circuit pack, and one protection STS1E circuit pack.
If a service DS3 or STS1E circuit pack fails, the input protection switching relays
on the failed circuit pack route the three low speed signals (DS3 or EC-1) to the
LSSW circuit pack in the IN slot. The LSSW circuit pack in the IN slot switches the
three low speed signals (DS3 or EC-1) to the protection DS3 or STS1E circuit
pack. In the receive direction, the LSSW circuit pack in the OUT slot accepts the
three low speed signals (DS3 or EC-1) from the protection circuit pack (DS3 or
STS1E) and routes them to the output protection switching relays on the failed
circuit pack and on to the DSX-3 or STSX-1 panel (or equivalent).
Shorting contacts are provided in the DS3 or STS1E circuit pack backplane
connector 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.
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