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Quad Fiber Remote (QDFR) Unit Installation and Maintenance Practice
A-2 61181307L7-5E
Loopback Control Codes
A summary of control sequences is given in Table A-1. All codes must be sent for a minimum
of 5 seconds to be detected and acted upon.
NOTE
In all control code sequences presented, the in-band codes are
shown left-most bit transmitted first, and the ESF data link codes
with right-most bit transmitted first.
Table A-1. Loopback and Control Codes
Pattern Description Source Arming
Required
1in3
Loopdown QDFC and QDFR and disarm
NET
CUST
No
3in7 QDFR DS1 loopback to network NET No
4in7 QDFC DS1 loopback to network NET No
5in7 QDFR DS1 loopback to customer CUST No
6in7 QDFC DS1 loopback to customer CUST No
3F1E QDFC DS1 loopback to customer CUST No
3F02 QDFR DS1 loopback to customer CUST No
3F02 QDFR DS1 loopback to customer NET Yes
FF1E QDFC loopback to network
Will not loopup QDFC if QDFC already in loopback to customer
NET No
FF02 QDFR loopback to network
Will not loopup QDFR if any unit already in loopback to customer
NET No
2in5 Arm QDFC and QDFR. QDFR DS1 will loopup (toward Network only) if
NIU LB is enabled
NET
CUST
No
3in5 Disarm and loopdown QDFC and QDFR
Restores Loopback Timeout Override after D5D6
NET
CUST
No
D3D3 QDFC DS1 loops up toward pattern: 2 seconds AIS, 5 seconds data,
then 231 bit errors toward pattern. 231 bit errors every 20 seconds as
long as the pattern is present
NET
CUST
Yes
C742 QDFR DS1 loops up toward pattern: 2 seconds AIS, 5 seconds data,
and then 20 bit errors toward pattern. 20 errors every 20 seconds as
long as pattern present
NET
CUST
Yes