Maintenance Description
9-76 Issue 8.0 July 2002
The LSSW circuit packs are tested to verify they can perform a low-speed
protection switch for each low-speed interface circuit pack. The
transmission path through the LSSW circuit packs is tested in the DSX test.
Each TG3 (DS1) circuit pack is also tested individually to detect
transmission and cross-cabling errors. The local test disables the reference
signals on each TG3 (DS1) circuit pack and verifies the correct TG3 (DS1)
circuit pack detects the loss of reference signal. If the correct TG3 (DS1)
circuit pack detects the loss of reference signal, the test passes.
â– DSX (Low Speed Cabling Self-Test):TheFAULT-Test-Auto
Turnup-DSX input verifies the low-speed cabling between the FT-2000
OC-48 Add/Drop-Rings Terminal and the cross-connect panel (or
equivalent) was installed properly and supports transmission. The test
verifies that the input and output low-speed interface cables are connected
to the same port at the terminal and the cross-connect panel (or
equivalent). The DSX test also performs low-speed switches for each
electrical low-speed interface circuit pack (DS3 and STS1E) and tests the
transmission path through the LSSW circuit packs. The LSSW circuit packs
are in the transmission path between the protection electrical low-speed
interface circuit pack and the cross-connect panel (or equivalent).
For the DSX test, the fiber(s) for the line(s) to be tested must be
disconnected and each low-speed port of the line(s) to be tested must be
looped back at the DSX-3 cross-connect panel (or equivalent). See
Figure 9-26.
Figure 9-26. DSX (Low Speed Cabling Self-Test)
The following tests are performed:
— To verify the continuity of each transmission path, each DS3 circuit
pack inserts one parity bit error on each DS3 signal toward the
cross-connect panel (or equivalent). The DS3 signals are looped
Multiplexing Direction
DSX
Demultiplexing Direction
Test Signal
DSX
Loop
Monitor
Internal
Low Speed Interface
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