Verilink DCSU 2911 (880-502647-001) Product Manual - Manual (Page 70)

Troubleshooting
5-4 Verilink DCSU 2911 User Manual
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 5-1 DCSU 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 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 Craft 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).