Specifications

Chapter 6 Diagnostics and Troubleshooting Installation and Operation Manual
6-4 Monitoring Performance IPmux-24 Ver. 1.5
Alarm Description
RAI (Yellow) Number of seconds with Remote Alarm Indicators. A Remote Alarm Indicator is sent by a
device when it enters RED state (loses sync).
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 is also indicated by the front panel ALM LED (red).
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 Number of seconds with Alarm Indication Signals. 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.
The AIS condition is indicated by the front panel E1/T1 SYNC LED (red).
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).
FEBE Number of seconds with Far End Block Errors. The FEBE is sent to transmitting device
notifying that a flawed block has been detected at the receiving device. Exists only for E1
MF-CRC4. The FEBE alarm is also indicated by the front panel ALM LED (red).
The FEBE counter will increase by one for each second during which the FEBE indication is
received.
Recommendation:
Check physical link integrity.
BES Bursty Errored Seconds (also known as Errored seconds type B) are seconds during which
fewer than 319 and more than one CRC errors occurred with neither AIS nor SEF (Severely
Errored Frames) detected. The BES counter will increase by one for each second containing
the condition described above. The CRC is calculated for the previous frame in order to
prevent processing delay.
Complies with AT&T TR-62411 and TR-54016 standards. Not applicable if the line type is set
to Unframed. Available only at T1-ESF or E1-CRC4 modes (performance monitoring
functionality).
Recommendations:
Check physical link integrity, G.704 frame format integrity and Sync. (The CRC bits are
included in TS0 for E1 multiframe links and in the frame alignment bits for T1 ESF links).