The black-hole-dup-mac command configures flapping MAC routes as black-hole routes.
The undo black-hole-dup-mac command restores the default configuration.
By default, flapping MAC routes are not set to black-hole routes, and the AC interface that generates flapping MAC routes is not blocked.
Usage Scenario
On an EVPN E-LAN, two PEs may be interconnected both through network-side and access-side links. If this is the case, a BUM traffic loop and MAC route flapping both occur, preventing devices from working properly. In this case, MAC duplication suppression on the devices works. By default, the system checks the number of times a MAC entry flaps within a detection period (180s by default). If the number of MAC flaps exceeds the upper threshold (5 by default), the system considers MAC route flapping to be occurring on the network and consequently suppresses the flapping MAC routes. The suppressed MAC routes cannot be sent to a remote PE through a BGP EVPN peer relationship. To set flapping MAC routes as black-hole routes, run the black-hole-dup-mac command. After this configuration is performed, if the source or destination MAC address of the forwarded traffic is the same as the MAC address of a black-hole MAC route, the traffic is discarded.