Specifications

Installation and Operation Manual Chapter 6 Troubleshooting and Diagnostics
IPmux-8/16 Ver. 6.00 Monitoring IPmux-8/16 Performance 6-7
Table 6-3. E1/T1 Statistic Parameters (Cont.)
Alarm Description Recommendation
LOF (Red) A Loss of Frame indicates that the IPmux lost E1/T1 synch opposite its
adjacent E1/T1 device.
In more detail, this is a period of 2.5 seconds for T1 or 100 msec for E1,
during which an OOF (Out Of Frame) error persisted and no AIS errors
were detected.
For E1 links an OOF defect is declared when three consecutive frame
alignment signals have been received with an error.
For T1 links, an OOF defect is declared when the receiver detects two
or more framing errors within a three msec period for ESF signals and
0.75 msec for D4 signals, or two or more errors out of five or fewer
consecutive framing bits.
A LOF alarm can also be noticeable when the SYNC LED is off.
When the IPmux enters a Red alarm condition, it sends an Yf bit (Yellow
alarm or RAI) towards the adjacent E1/T1 device.
Check all framing related
parameters (CRC-4, CAS
enabled/disabled, ESF/D4 (for
T1), etc.), and physical
connections.
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.
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
(loses synch).
RAI 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 SYNC LED is flashing.
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 LED turns off.
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 A Far End Block Error 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 counter will increase by one for each second during which
the FEBE indication is received.
Check physical link integrity.