Verilink DPRI 2922 (880-503142-001) Product Manual - Manual (Page 82)

Troubleshooting
4-4
Verilink DPRI 2922
Alarm List
Fault conditions can result in critical, major, or minor alarms. In
addition, a fault condition can also result in a Carrier Failure Alarm
(CFA).
Table 4-1 Alarms
Alarm Classification/
Alarm Type Description
Critical Alarms A critical alarm indicates the node or node components have failed. Only the
loss-of-clock (LOC) error condition triggers a critical alarm. This error causes
the system clock to fail and prevents data from being transmitted.
Loss-of-clock causes the System LED to flash red. It causes a major alarm and
activates the relay contacts on the rear connector panel of the CIM.
Carrier Failure Alarm (CFA) A carrier failure alarm (CFA) is activated when certain major alarm error
conditions occur, causing the port to disrupt traffic along the line. When the
CFA is activated, the line is not useable—preset by the user—for 2 to 60
seconds. All traffic is removed from the line. The alarm remains active until
the port is reconfigured.
Major Alarms
A major alarm fault condition seriously affects performance. It prevents data
from being reliably transmitted across the circuit. When a major alarm is
declared, the module sends a message to the ASCII interface and Node
Manager, lights the appropriate LED indicator, and trips the alarm relay. The
following error conditions must persist for at least one second for a major
alarm to be declared.
Alarm Type Description
Loss of
Signal
(LOS)
This condition occurs when the network signal is absent, and exceeds a
predefined loss-of-signal threshold. An LOS alarm on a network line is
declared when more than 175 consecutive zeros are detected on input to the
receiving equipment. An LOS after one continuous second causes a major
alarm and activates the relay contacts on the rear connector panel of the CIM.
This alarm activates the CFA if the LOS is active from 2 to 45 seconds (as
defined by the user).
Alarm
Indication
Signal (AIS)
Using an unframed ALL-ONEs bit pattern, an AIS alarm indicates that an alarm
condition exists upstream in a circuit leading to the downstream equipment.
This is also called an ALL-ONEs Keep-Alive or Red Alarm Signal. An AIS defect
is declared when there are 3 or fewer zeros in 512 bit times and an LOF
defect. It is cleared when there are 3 or more zeros in two frames or the LOF
defect no longer exists.
This alarm activates the CFA if the AIS is active from 2 to 45 seconds (as
defined by the user).
Loss of
Frame (LOF)
(T1 Only)
This alarm is declared when a 3-second interval of continuous Out-Of-Frame
(OOF) or Loss-Of-Signal (LOS) state is detected. An LOF alarm is cleared when
at least 10 seconds of continuous non-LOS or non-LOF condition exists.
This alarm activates the CFA if the LOF is active from 2 to 45 seconds (as
defined by the user).