Line Drawer Faults; Link Failure - Nortel DMS-100 Series Maintenance Manual

1-34 Maintenance overview

Line drawer faults

A BIC or line card that has faults causes a fault condition in a line drawer.
This fault does not cause a takeover.

Link failure

DS-1 links
Link failures normally associate with the DS-1 interface cards in the host
controller or DS-1 link. Link failures also associate with the DS-1 interface
cards in the OPAC. The system monitors through operational measurements
(OM), which indicate when maintenance or OOS thresholds are exceeded.
The host controller performs the following actions:
Operating company personnel can perform the following actions to obtain
the bit error rate (BER) count at the OPAC:
The BER identifies the number of bipolar violations (BpV). The BpVs do
not raise an alarm but can signal link wear.
The signals on a DS-1 link travel in two directions. This condition allows
the host controller or the OPAC to detect faults like BpVs. The OPAC
notifies the host controller when the BpV count exceeds the threshold of 1
BpV per 10
The OPAC monitors the loss of frame indicator for the DS-1 links. The
OPAC turns on an outgoing alarm for any frame loss of more than 2.5 s.
The system removes the outgoing alarm when the frame restores for 10 s.
Frame loss at the OOS limit occurs in one of the following events:
A local carrier group alarm (LCGA) appears at the CARRIER level of the
MAP display if the host XPM detects loss of frame.
297-8211-550 Standard 05.01 August 1999
maintains and tests the DS-1 links
generates alarms for link faults
reassigns channels when faults occur on these links
post the host multiprocessor system-based peripheral module (XPM) like
the LGC or LTC
enter the command string POST REMOTE at the CARRIER level of the
MAP display
3
bits.
the OPAC detects loss of the framing pattern for 2.5 s or more
the host XPM detects loss of the framing pattern for 220 ms