You can classify communication between NXDB and the external controller in a Control Plane Policing (CoPP) management class. Doing so avoids congestion of the default CoPP class that affects the control communication.

copp copy profile strict prefix controller
ip access-list controller-copp-acl
		10 permit tcp any any eq 6640
		20 permit tcp any eq 6640 any
		30 permit tcp any any eq www
		40 permit tcp any eq www any
		50 permit tcp any any eq 443
		60 permit tcp any eq 443 any

class-map type control-plane match-any controller-copp-class-management
		match access-group name controller-copp-acl
control-plane
		service-policy input controller-copp-policy-strict

All MAC addresses, whether local or remote, are installed as dynamic MAC addresses. The local MAC addresses are learned from the data plane and have aging enabled on them. The remote MAC addresses are learned from the external controller and have aging disabled on them. MAC addresses learned from the external controllers can be deleted from the system (from both Cisco NX-OS and the Cisco Nexus hardware) only when the external controller sends a delete message.

To delete the local and remote MAC addresses from the hardware and then redownload the remote MAC addresses to the hardware from the object store database maintained in Cisco NX-OS, enter the clear mac address-table dynamic command from the exec configuration mode on the switch.

To delete the remote MAC addresses from NXDB, the object store, and the hardware, enter the guestshell run sudo ovsdb-plugin db del ucast-macs-remote --mac 00:00:00:00:00:01 --vlan 1001 command in NXDB. The OVSDB RFC causes the external controller to redownload the MAC addresses to NXDB.