Cisco ONS 15454 Troubleshooting Manual page 356

2.7.221 LOS (EC1)
Step 5 Use a test set to confirm that a valid E1 signal exists on the line. Test the line as close to the receiving
card as possible. (For specific procedures to use the test set equipment, consult the manufacturer.) If the
test set shows errors, the cabling could still be faulty despite being correctly installed. Use the tester to
isolate the bad section of cable and replace it. Refer to the "Install Cards and Fiber-Optic Cable" chapter
in the Cisco ONS 15454 Procedure Guide for procedures.
Repeat Steps
Step 6
If the alarm does not clear, look for any card-level alarm that could cause this alarm.
Step 7
Step 8 If the alarm does not clear, complete the
for the reporting card.
If the alarm does not clear, log into the Technical Support Website at http://www.cisco.com/techsupport
Step 9
for more information or call Cisco TAC 1 800 553-2447 in order to report a Service-Affecting (SA)
problem.
2.7.221 LOS (EC1)
LOS on an EC1/EC1-12 or DS3/EC1-48 port occurs when a SONET receiver detects an all-zero pattern
for 10 microseconds or longer. An LOS (EC1) most likely means that the upstream transmitter has failed.
If an EC1 LOS alarm is not accompanied by additional alarms, a cabling problem (such as an incorrect
attachment, fiber cut, or other fiber error) usually causes this alarm. The condition clears when the
problem is corrected, allowing two consecutive valid frames to be received.
If a circuit shows a partial status when this alarm is raised, the logical circuit is in place. The circuit is
Note
able to carry traffic when the connection issue is resolved. You do not need to delete the circuit when
troubleshooting this alarm.
Clear the LOS (EC1) Alarm
Caution Always use the supplied electrostatic discharge wristband when working with a powered ONS 15454.
Plug the wristband cable into the ESD jack located on the lower-right edge of the shelf assembly.
Step 1 Check for any upstream equipment failures that could cause the LOS (EC1) in this node.
Step 2 If there is no cause upstream, verify cabling continuity from the transmitting port to the receiving port
reporting LOS (EC1) To verify cable continuity, follow site practices.
If the continuity is good, clean the fiber according to site practice. If none exists, complete the procedure
in the "Maintain the Node" chapter in the Cisco ONS 15454 Procedure Guide.
If the cabling is good, verify that the correct EC1-12 port is in service:
Step 3
a.
b.
Cisco ONS 15454 Troubleshooting Guide, R8.5
2-162
1 to 5 for any other port on the card that reports the LOS (E1).
Default Severity: Critical (CR), Service-Affecting (SA)
SONET Logical Object: EC1
Confirm that the LED is correctly lit on the physical card.
A green ACT/SBY LED indicates an active card. An amber ACT/SBY LED indicates a standby card.
To determine whether the port is in service, double-click the card in CTC to open the card view.
"Physically Replace a Traffic Card" procedure on page 2-273
Chapter 2 Alarm Troubleshooting
November 2009