Specifications

Chapter 4 Troubleshooting and Diagnostics IPmux-1/1E Installation and Operation Manual
4-8 Performance Monitoring and Troubleshooting Statistics
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).