Specifications

1-50
Cisco ONS 15454 Troubleshooting and Maintenance Guide
November 2001
Chapter 1 Alarm Troubleshooting
1.3.71 LOF (OC-N)
• Critical, Service affecting
A port on the reporting OC-N card has an LOF condition. LOF indicates that the receiving ONS 15454
has lost frame delineation in the incoming data. LOF occurs when the SONET overhead loses a valid
framing pattern for 3 milliseconds. Receiving two consecutive valid A1/A2 framing patterns clears the
alarm.
LOF on an OC-N card is sometimes an indication that the OC-N card reporting the alarm expects a
specific line rate and the input line rate source does not match the input line rate of the optical receiver.
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 outside edge of the shelf
assembly.
Procedure: Clear the LOF Alarm on an OC-N Card
Step 1 The LOF should trigger an automatic protection switch away from the working card that reported the
alarm. If it did not, do a manual switch to move traffic away from the reporting card:
a. At the node view, click the Maintenance > Protection tabs.
b. Double-click the protection group that contains the reporting card.
c. Click the Protect/Standby card of the selected groups.
d. Click Manual and OK.
Note If you do not have a protect card for the reporting card, create a new circuit on the
reporting card to achieve the same effect.
Step 2 Clear the manual switch:
a. At the node view, click the Maintenance > Protection tabs.
b. Double-click the protection group that contains the reporting card.
c. Highlight either selected group.
d. Click Clear and click YES at the confirmation dialog box.
Step 3 Verify that the OC-N port on the upstream node is in-service.
Step 4 If you continue to receive the LOF alarm, see the “Faulty Fiber-Optic Connections” section on
page 2-29.
1.3.72 LOP-P
• Critical, Service affecting