Verilink NCC 2020 (880-503284-001) Product Manual User Manual
Page 57
Diagnostics
Verilink NCC 2020 User Manual
5-9
Figure 5-4
Sending and Receiving Pattern
If the QRSS pattern is received with no errors, the Test Error
Counter will not increment.
If the Test Error Counter does increment, one of the following
applies:
•
The far end CSU never went into a loopback and therefore the
test pattern being transmitted is not being received at all. This
would cause the Test Error Counter to increment at a rapid and
steady rate.
•
The far end CSU did go into a loopback, but the pattern
received at the local NCC 2020 does not match the pattern
transmitted. In this case the Test Error Counter might
increment in uneven amounts at virtually any rate.
Results
If the test passes, consider doing the same test with a different
pattern. Some patterns will fail on a T1 which passes other test
patterns. See
for details on the various patterns.
Test Failures
If the test fails consider one of these alternatives:
•
Use a loopback closer to the local CSU. The telephone carrier
may be able to put up loopbacks at various locations along the
path of the T1 circuit. Start far away and work your way back
to the local CSU.
•
If it appears that the local CSU is defective, try using a
repeater loopback. Send a test pattern while the local CSU is in
repeater loopback. The test pattern never leaves the CSU
because it is receiving what it is sending. If this test passes,
the CSU is probably OK.
•
If a problem is identified but not resolved by this procedure,
go on to the next section, “
Test pattern sent
Far CSU
Test pattern received
(in Line Loop)
Local NCC 2020
Sends pattern
Checks pattern