Fiber Line Unit Maintenance Modes
61181307L7-5E
A-3
1. Units must be armed with 11000b or FF48h before this code will work.
2. Loopback and error injection will only occur if the in-band code is received by the unit that is to go into loop-
back. If another loopback blocks the in-band code from being transmitted to the unit that is to go into loopback,
loopback and error injection will not occur.
NOTE
All codes listed above must be sent for a minimum of 5 seconds to
be detected and acted upon.
9393
Loopdown QDFC DS1 – either direction
Loopdown QDFR DS1 – customer loopback always; will only loopdown
QDFR network loopback if NIU is disabled
Does not disarm units if they are armed
NET
CUST
No
D5D5
If unit is in loopback towards pattern, errors are periodically injected
toward pattern as long as pattern is present
QDFC: 231 errors every 20 seconds
QDFR: 20 errors every 20 seconds
NET
CUST
No
D5D6
Loopback Timeout Override
Disables loopback timeout; restores original loopback timeout when
unit is disarmed
If unit is in loopback towards pattern, errors are periodically injected
toward pattern as long as pattern is present
QDFC: 231 errors every 20 seconds
QDFR (Network loopback): 20 errors every 10 seconds
QDFR (Customer loopback): 20 errors every 20 seconds
NET
CUST
Yes
FF48
Arm QDFC and QDFR DS1
QDFR will Loopback (toward Network only) if NIU enabled
NET
No
FF24
Loopdown and disarm QDFC and QDFR DS1
Restores Loopback Timeout Override after D5D6
NET
CUST
No
Table A-1. Loopback and Control Codes (Continued)
Pattern
Description
Source
Arming
Required
