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Cisco ONS 15454 Troubleshooting Guide, R8.5
November 2009
Chapter 2 Alarm Troubleshooting
2.7.216 LOS (2R)
Clear the LO-RXPOWER Alarm
Step 1 At the transmit end of the errored circuit, increase the transmit power level within safe limits.
Step 2 Find out whether new channels have been added to the fiber. Up to 32 channels can be transmitted on
the same fiber, but the number of channels affects power. If channels have been added, power levels of
all channels need to be adjusted.
Note If the card is part of an amplified DWDM system, adding channels on the fiber affects the
transmission power of each channel more than it would in an unamplified system.
Step 3 Find out whether gain (the amplification power) of any amplifiers has been changed. Changing
amplification also causes channel power to need adjustment.
Step 4 If the alarm does not clear, remove any receive fiber attenuators or replace them with lower-resistance
attenuators.
Step 5 If the alarm does not clear, inspect and clean the receive and transmit node fiber connections according
to site practice. If no site practice exists, complete the procedure in the “Maintain the Node” chapter in
the Cisco ONS 15454 Procedure Guide.
Step 6 If the alarm does not clear, ensure that the fiber is not broken or damaged by testing it with an optical
test set. If no test set is available, use the fiber for a facility (line) loopback on a known-good port. The
error reading you get is not as precise, but you generally know whether the fiber is faulty. For specific
procedures to use the test set equipment, consult the manufacturer.
Step 7 If the alarm does not clear, and no faults are present on the other port(s) of the transmit or receive card,
do a facility loopback on the transmit and receive ports with known-good loopback cable. Complete the
“1.4.1 Perform a Facility Loopback on a Source-Node Optical Port” procedure on page 1-48 or the
“1.4.4 Perform a Facility Loopback on an Intermediate-Node Optical Port” procedure on page 1-57 to
test the loopback.
Step 8 If a port is bad and you need to use all the port bandwidth, complete the “Physically Replace a Traffic
Card” procedure on page 2-273. If the port is bad but you can move the traffic to another port, replace
the card at the next available maintenance window.
Step 9 If no ports are shown bad and the alarm does not clear, log into the Technical Support Website at
http://www.cisco.com/techsupport for more information or call Cisco TAC 1 800 553-2447.
2.7.216 LOS (2R)
For information about this alarm or condition, refer to the “Alarm Troubleshooting” chapter in the
Cisco ONS 15454 DWDM Troubleshooting Guide. This guide discusses all DWDM alarms.
2.7.217 LOS (BITS)
Default Severity: Minor (MN), Non-Service-Affecting (NSA)
SONET Logical Object: BITS
The LOS (BITS) alarm indicates that the TCC2/TCC2P has an LOS from the BITS timing source. The
LOS (BITS) means the BITS clock or the connection to it failed.
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