Verilink APS 2000 T1 Line Protection (880-502411-001) Product Manual - Manual (Page 71)

Diagnostics
Verilink APS 2000 User Manual 5-7
Signal Access
Jacks
The SCC 2120 also has three pairs of bantam jacks for signal access
by an external T1 test set.
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.
3) 1 in 8 Starts 1 in 8 test. CSU transmits a 1 in 8 pattern, which guarantees one bit of
every 8 will be a one, while monitoring the receive pair for
the same signal to be returned.
This test pattern is valid for all T1 circuit types.
4) all 1 Starts all ones pattern
Use of this pattern is
suggested whenever
any T1 circuit is
tested.
The CSU transmits a framed pattern of all ones and monitors
receive data for the same pattern.
Because it produces maximum current levels, this test is
especially good at finding some problems like bad repeater
cards or resistive punchdown connections.
All ones is a valid test on all T1 circuits.
L) line Initiates a line
loopback.
Line loopback faces the T1 circuit, all data received from the
T1 circuit is sent back to the T1 circuit.
This is the same loopback which occurs when a CSU receives
a loop-up code from the network.
P) payload Initiates a payload
loopback.
Payload loopback faces the T1 circuit like the line loopback.
A payload loopback passes through more of the CSU circuitry
while the line loopback occurs closer to the network port.
U) inband up Sends a standard CSU
loop-up code toward
the far end CSU.
Under normal circumstances sending the line loop-up code
will cause the far end CSU to enter a line loopback state.
D) inband down Sends a standard CSU
loop-down code to the
far end CSU.
Under normal circumstances sending the line loop-down
code will terminate a line loopback state in the far end CSU.
Menu Option Description Instructions