When a system administrator configures Cisco ACI, they have the ability to configure link aggregation. Aggregation bundles multiple physical links into a single logical link to increase bandwidth and redundancy. If one of the physical links in the bundle goes down, the logical link remains up as long as there is at least one physical link still up.
If a physical link goes down, LACP will mark that link as “suspended.” This prevents traffic from being sent over the link. When the link comes back up, LACP will automatically re-enable it.
Suspended links can be caused by a number of things, including:
- Physical link down
- Configuration mismatch
- Misconfigured LACP
If you see that a link is suspended, you can use the “show lacp” command to see more information about the suspended link. This command will show you the reason for the suspension and the interface that is suspended.
If you see that a link is suspended due to a configuration mismatch, you can use the “lacp config-sync” command to resolve the issue. This command will synchronize the LACP configuration across all of the devices in the system.
If you see that a link is suspended due to a misconfigured LACP, you can use the “no lacp” command to disable LACP on the interface. You can then use the “lacp” command to re-enable LACP and correct the configuration.