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.
3) 1 in 8
4) all 1
Starts all ones patter
Use of this pattern is suggested whenever
any T1 circuit is tested.
n. The CSU transmits a framed pattern of all ones and monitors receive data for the same pattern.
B e c a u s e i t p r o d u c e s m a x i m u m c u r r e n t l e v e l s , t h i s t e s t i s especially good at finding some problems like bad repeater cards or resistive punchdown connections.
All ones is a valid test on all T1 circuits.
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.
U) inband up
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.
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.
Verilink NCC 2020 User Manual