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IPmux-1/1E Installation and Operation Manual Chapter 4 Troubleshooting and Diagnostics
Performance Monitoring and Troubleshooting Statistics 4-9
Table 4-3. E1/T1 Alarms (Cont.)
Alarm Description
LCV A Line Code Violation indicates an error on the pulse structure, either a Bipolar Violation (BPV) or an Excessive Zeros (EXZ) error event.
BPV is the occurrence of a pulse with the same polarity as the previous pulse.
EXZ is the occurrence of a zero string greater than 15 for AMI or 7 for B8ZS.
For an E1 link, the LCV counter will increase by one, for each second during which a BPV or EXZ errors have occurred.
For T1 links, the LCV counter will increase for each second during which two consecutive BPVs of the same polarity are received.
Complies with ITU-TI.431, 0.161, G775 and G.821 standards.
Recommendations:
Check physical link for bad/loose connection, impedance matching (balanced or unbalanced) and noisy environment.
RAI (Yellow) A Remote Alarm Indicator is sent by a device when it enters RED state (looses synch).
RAI Alarm indicates that the adjacent E1/T1 device had lost E1/T1 synch and hence sent an RAI towards the IPmux, which entered a Yellow alarm mode
(similarly, IPmux sends RAI towards adjacent E1/T1 when IPmux enters LOF state (Red alarm).
In both E1/T1 links the RAI counter increases by one for each second during which an RAI pattern is received from the far end framer.
The RAI alarm can also be noticeable when the front panel Sync LED is flashing.
Recommendations:
Check reason for E1/T1 device to be in LOF (out of synch state) by checking physical link integrity at the Tx direction of the IPmux towards E1/T1 device and
framing related parameters.
AIS An Alarm Indication Signal implies an upstream failure of the adjacent E1/T1 device. AIS will be sent to the opposite direction of which the Yellow alarm is
sent.
For E1 links, the AIS counter will increase by one for each second during which a string of 512 bits contains fewer than three zero (0) bits.
For T1 links, the AIS counter will increase by one for each second during which an unframed “all 1” signal is received for 3 msec.
When receiving AIS the Sync front panel LED is off.
Recommendations:
Check why the E1/T1 device is sending AIS (all ones) stream towards IPmux, for example, Red alarm on a different interface of E1/T1 device (upstream).