174
C
HAPTER
5: P
ATH
B
UILDER
S330 D
IAGNOSTICS
AND
P
ERFORMANCE
S
TATISTICS
IMA Tx
Misconnected
ATM Forum (R-123)
The near end IMA networking
Tx or Rx link state machine
detects the link is not
connected to the correct FE Tx
or Rx links.
Remove the link and stop Tx and Rx
data.
Loss of Differential
Synchronization
(LODS)
ATM Forum (R-122)
Relative time difference
between individual T1s/E1s in
the IMA group is out of range.
LODS is declared after the Rx
IMA fails to synchronize the
IMA link(s) in an IMA group
within some time limit.
Have your carrier verify the time synch
and routing of individual T1s/E1s in the
group. Check the IMA group
configuration to ensure consistency on
the local and remote ends.
Loss of IMA Frame
(LIF)
ATM Forum (R-121
)
Loss of IMA Frame is detected
in the Rx direction for an IMA
link UP.
There is an IMA frame size
mismatch between two ends
of the circuit. This can be
caused by missing ICP cells
(ATM cells that carry protocol
information), bad IMA ID, bad
sequence number, bad M, bad
offset HEC error or CRC error
in ICP cells. This problem may
occur if the link gets noisy and
there is no AFA to prevent the
ICP from getting corrupted. It
is detected in hardware and
may or may not cause an
operational problem.
Check the IMA group configuration to
ensure consistent frame size on the
local and remote ends. Check links for
evidence of noise. Check to be sure
that AFA is enabled.
Port Missing ICP
Cells
Two consecutive ICP cells
missing from the IMA frame.
See also
Loss of IMA Frame (LIF)
. This is
a specific cause of that alarm and will
also be reported.
RFI IMA
ATM Forum (R-121)
Remote Failure Indication: Far
end IMA Rx networking link
state machines detected LOS,
OOF, AIS. LCD, LIF or LODS.
Correct T1 or E1 facilities error.
Test Pattern Failed
An 8-bit pattern is sent to the
remote node which must then
echo it back on all ports. The
local node checks the echoed
pattern and reports an alarm if
cells from one or more of the
links fail to arrive. This alarm is
declared on all links which do
not reply or reply incorrectly.
Make sure that the same number of
links are configured and enabled on
both ends of the IMA configuration.
Make sure that the configuration of
both groups is the same. For instance,
make sure that the payload scrambling
setting is the same on both ends.
Yellow Alarm
OOF alarm is detected. A
received remote alarm
indication means that the far
end equipment has a problem
with the signal it is receiving
from the PathBuilder device.
Connect an external loopback cable to
the port. If there are no alarms, the
problem is elsewhere. Check for an
open, short, or wiring error in the cable
between the PathBuilder network
interface port and your service
provider's network interface unit, or
the terminal equipment. An open
transmit pair can cause this condition
Table 11
T1/E1 UNI with IMA Module Alarms (continued)
Alarm
Meaning
Troubleshooting Steps
