DS1-BD (DS1 Interface Circuit Pack)
Issue 4 May 2002
10-639555-233-123
Line Loopback Alarm
The Line Loopback (LLB) is used by the remote DS1 endpoint to put the ICSU or
DS1 into a loopback mode. When the ICSU or DS1 Board is in the LLB mode, the
arriving bit pattern is regenerated and sent back. Line Loopback (LLB) Alarm is
activated when the in-band activate LLB bit pattern has been arriving continuously
for 5 seconds on the DS1 line. LLB is deactivated when the in-band deactivate
LLB bit pattern has been arriving continuously for 5 seconds on the DS1 line.
Since LLB is a maintenance condition rendering all DS0 channels unavailable for
signaling or bearer traffic, maintenance software treats this the same as a Blue
Alarm.
Payload Loopback Alarm
The Payload Loopback (PLB) is used by the remote DS1 endpoint to put the
switch DS1 into a loopback mode. PLB Alarm is activated when a network
protocol activate bit pattern arrives over the 4-Kbps ESF data link on the DS1 line.
PLB is deactivated when a network protocol deactivate bit pattern arrives over the
4-Kbps ESF data link on the DS1 line.
Since PLB is a maintenance condition rendering all DS0 channels unavailable for
signaling or bearer traffic, maintenance software treats this the same as a Blue
Alarm.
Table 10-236. TEST #139 Blue Alarm Inquiry Test
Error
Code
Tes t
Result Description/Recommendation
ABORT Internal system error
2100 ABORT Could not allocate the necessary system resources to run this
test.
1. Retry the command at 1-minute intervals a maximum of 5
times.
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