Verilink NCC 2020 (880-503284-001) Product Manual - Manual (Page 52)

Diagnostics
5-4 Verilink NCC 2020 User Manual
Diagnostic
Commands
There are seventeen command options available on the NCC 2020
diagnostics menu.
Table 5-2 lists all of these commands.
Drawings which illustrate the various loopbacks can be found in
the manual
AS2000, The Basics .
Table 5-2 Diagnostic Commands
Menu Option Description Instructions
X) exit menu Exits to menu above. Returns to the NCC 2020 Main Menu .
Y) enable loops Determines whether
CSU will respond to
received standard CSU
loop-up codes.
Normally this selection should be enabled.
In a telephone carrier central office environment this option
might be disabled.
Z) reset alarm Clears alarm history
for the current 15
minute interval.
Extinguishes red LED alarm conditions on front panel of the
NCC 2020 CSU after installation or after resolving a service
problem.
T) test time Sets the length of time
tests and loopbacks
will be allowed to run.
FOREVER is suggested
by Verilink.
ENTER INTERVAL (DEFAULT, x SEC, x MIN, x HR, FOREVER):
Type FOREVER or type a numeric value followed by SEC for
seconds, MIN for minutes, HR for hours.
Example “ 45MIN” .
R) repeater Establishes a repeater
loopback.
Useful for testing local
CSU hardware.
The CSU loops data it is about to transmit back to the receive
circuitry. Local equipment should see its own signal.
This test is functionally equivalent to placing a T1 loopback
plug into the network port of the CSU.
E) equip Establishes an
equipment loopback.
The local DSX-1 equipment port is looped back directly to the
local equipment. Useful for verifying cable connections.
A) show cntr Displays test error
counter, increments
for each error
detected.
Used to monitor a test in progress. When the CSU transmits a
test pattern, it expects to receive the same test pattern
unaltered, either from a loopback or a compatible test signal
source.
B) clear cntr Resets test error
counter.
Used to reset the test error counter to zero after a test or
before a new test.
N) end tests Ends tests and local
loopbacks.
Used to end any running test patterns as well as terminating
any loopbacks in the local CSU.
1) qrss Starts QRSS test. CSU transmits a Quasi-Random test pattern while monitoring
the receive pair for the same signal to be returned.
This test is widely supported by telephone carrier test
facilities.
This test pattern is valid for all T1 circuit types.
2) 3 in 24 Starts 3 in 24 test. CSU transmits a 3-in-24 test pattern while monitoring the
receive pair for the same signal to be returned.
3-in-24 guarantees that of any 24 bits sent, at least 3 will be
ones, thus strings of twenty one contiguous zeroes are
possible.
Because this pattern may have strings of up to 21 zeroes in a
row, it may fail on some perfectly good AMI T1 circuits as
equipment in the circuit enforces ones density.