Alcatel-Lucent 7330 Product Information Manual page 45

The system is designed to automatically identify these ONT fault or error conditions
using alarms, statistics, or automatic action. This tells operators of a problem or
disables the ONT so a single rogue ONT cannot affect the entire PON.
Laser stuck on
ONTs use watchdog timers to stop errors that cause light to be continuously sent up
the fiber. These watchdog timers are maintained by the software. When a watchdog
timer fails, the hardware triggers a reset. When a reset is triggered, the laser is
disabled. Before the laser retransmits, the ONT software must pass power on and self
tests.
Duplicate serial numbers
An ONT is automatically disabled when:
•
A ranged ONT sends a broadcast PONID within a serial number PLOAM
message. This indicates the ONT may not be aware of its ranged state or that a
second ONT using the same serial number is on the PON.
•
An ONT sends a serial number PLOAM message that does not match its assigned
ID.
•
An ONT sends a serial number PLOAM message but the ONT has not been
assigned a PONID.
•
A deactivate PLOAM message has been sent to the ONT three times and the ONT
has not deactivated. The ONT is then sent a disable PLOAM message.
Receive and transmit errors
There are two ways to identify marginal receive problems:
1 Self correcting CRC check for the time slot; if the time slot allocation fails a CRC
check, the ONU does not transmit in that time slot.
2 Increasing rate of becdown (Bit Error Rate Count Downstream) statistics.
There is one way to identify marginal transmission timing and level problems. If a
marginally transmitting (due to timing or optical signal levels) ONT does range,
upstream data from that ONT and possibly other ONTs on the PON will be
corrupted. Increasing rates of becup (Bit Error Count Upstream) statistics are seen.
The becup counters of the marginally transmitting ONT increase the fastest. Other
ONTs may see smaller increases.
Alcatel-Lucent 7330/7302 ISAM FTTN R04.02.41
3FE 54017 AAAA TCZZA
December 2010
Edition 01 ONT Product Information Guide
1 — ONT and MDU overview
1-21