Types of MAC address entries
A MAC address table can contain the following types of entries:
Static entries—A static entry is manually added to forward frames with a specific destination MAC address out of the associated interface, and it never ages out. A static entry has higher priority than a dynamically learned one.
Dynamic entries—A dynamic entry can be manually configured or dynamically learned to forward frames with a specific destination MAC address out of the associated interface. A dynamic entry might age out. A manually configured dynamic entry has the same priority as a dynamically learned one.
Blackhole entries—A blackhole entry is manually configured and never ages out. A blackhole entry is configured for filtering out frames with a specific source or destination MAC address. For example, to block all frames destined for or sourced from a user, you can configure the MAC address of the user as a blackhole MAC address entry. A blackhole entry has higher priority than a dynamically learned one.
A static or blackhole MAC address entry can overwrite a dynamic MAC address entry, but not vice versa. A static entry and a blackhole entry cannot overwrite each another.