CAC check errors are displayed when you create a link. Hence, you need to delete the useless connections on the port.
Product

OptiX OSN 1500A/1500B
OptiX OSN 2500
OptiX OSN 3500
OptiX OSN 7500
Fault Type

Configuration_Problem
Symptom

When you create a connection, a CAC check error is displayed. A connection fails to be created.
Cause Analysis

The boards support the CAC check function. If a link needs to be created, and if the sum of selected traffic rate and the traffic rate of all the existing links at the port exceeds the total bandwidth of the port, a CAC check error is displayed. Consequently, the link fails to be created.
Procedure

Make sure that the selected traffic rate is less than the remaining bandwidth of the port when you create a link. Delete the links that are not required at the port, and then create new links again.
Reference Information

None.