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Diagnostics and Troubleshooting
7-7
8000-A2-GB26-00
May 1998
Table 7-3. Minor Alarms (2 of 2)
Failure Type Action
Link Down
Threshold
(A trap
message is
sent if the
number of
DSL link
down events
in
15 minutes
exceeds the
selected
value.)
H If the threshold is set low (1–4), and the link is currently down, then
there may be a loop or SN problem. Check both.
– Verify that the SN is powered up, is connected to the loop, and has
passed its Selftest.
– Check the loop for continuity
H If the threshold is set low (1–4), and the link is currently up, then an
event had occurred to temporarily knock out the connection. Log the
event and continue normal operation.
H If the threshold is set high (> 4), and the link is currently down, then
check the Margin statistics over the past hour and day. If the numbers
are low, there may be a situation where the DSL modems cannot
train. This condition may be temporary or permanent. However, if it
persists, the loop may have to be reengineered for better
performance by performing one of the following:
– Remove bridge taps
– Change cable gauge on a cable section
– Run new cable
– Remove other noise-generating digital circuits from the cable
bundle
H If the threshold is set high (> 4) and the link is currently up, then there
may be a loose connection in the loop plant, or the loop is barely
usable. Check the Margin. If the Margin is normal, there may be a
loose connection. If the Margin is low, try reducing the speed of the
DSL port.