Fault Isolation for Fiber Links
Issue 1 May 2002
4-23555-233-143
In a duplex-, or high-reliability system (unduplicated PNC), did the test
return “Board not inserted” for either the near-end circuit pack
(nearest the server) or far-end circuit pack? If so, replace the cabling
between the DS1C circuit pack and the SNI or EXP-INTF circuit pack.
Wait 1 minute and retest.
If the board is still not inserted, replace the DS1C circuit pack and the
EXP-INTF or SNI connected to it, and return to step 4.
If No, check to see if any of the CSU devices are looped back. Busyout
and test ds1-facility UUCSS external-loop for each DS1 facility. The
tests should fail.
If any test passes, the facility is looped back, and the loopback should be
removed. If the DS1C complex has only one DS1 facility, this test cannot
be executed at the far-end circuit pack (farthest from the server).
Did Test #788 pass and Test #789 fail? If yes, at the other end of the DS1C
complex, replace the DS1C and its lightwave transceiver (if present). See
Figure 4-4 on page 4-25 and Figure 4-5 on page 4-26. Return to step 4.
If No, did Test #788 fail or abort and Test #789 fail or abort? If yes, execute
test ds1-facility UUCSS long command for each administered and
equipped DS1 facility.
If No, did Test #797 fail?
If Yes, run the test ds1-facility UUCSS external-loopback command for
each administered and equipped DS1 facility.
This test requires manually altering the external connections of the DS1
facility. Place the loopbacks at as many points as your CSU capabilities
will allow (see Figure 4-5 on page 4-26).
■ If Test #799 fails at LB1, the problem is with DS1C #1, CSU #1, or
the connections in between.
■ If Test #799 passes at LB1 but fails at LB2, the problem is with
CSU #1.
■ If Test #799 passes at both LB1 and LB2, the problem is with the
DS1 facility, CSU #2, connections to CSU #2, or DS1C #2.
SNI/EI Manual Loop-Back Procedure
NOTE:
Do not use this procedure on a connection with a DS1C as an endpoint.
Use this procedure to isolate a fault in the cables or lightwave transceivers of an
SNI/EI link. By performing the loopback at both endpoints and, if applicable, at the
cross-connect field, the failure point can be identified. If both endpoints pass but
the link remains inactive (with the boards not busied out), the fault should lie in the
cabling between. If the test passes at a transceiver but fails at the cross-connect
field, the cable or connectors in between are at fault.
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