Verilink SCC 2130 (880-503282-001) Product Manual - Manual (Page 63)

Diagnostics
Verilink SCC 2130 User Manual 5-9
Far End Loop To begin the verification, use the Inband Up command on the
Diagnostics Menu. This causes the local CSU to transmit a loop-up
code in the direction of the far end CSU
Figure 5-3 Sending Loop-up Code.
If the loop-up code reaches the far CSU and it is optioned to
respond to loop-up codes, then the far CSU enters a line loop
condition. Now the local CSU receives whatever it is sending.
NOTE: Whenever the Inband Up command is used to send a loop-up
code to a far end CSU, the Inband Down command must be
used later to send the loop-down code. Otherwise the far end
CSU will be left in a looped condition.
Sending A Pattern Begin transmitting a test pattern by using the qrss command.
Verify that the pattern received matches the pattern being
transmitted by using the show cntr command.
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 SCC 2130 does not match the pattern
transmitted. In this case the Test Error Counter might
increment in uneven amounts at virtually any rate.
Loop-up code
Far CSU Local SCC 2130
Test pattern sent
Far CSU
Test pattern received
(in Line Loop)
Local SCC 2130
Sends pattern
Checks pattern