There are three types of destination MAC address
filters:
(1) Block destination address at specific ports.
Indicates that the specified ports must not send frames
to the specified destination station address.
(2) Allow destination address at specific ports.
Indicates that the specified ports must send frames to
the specified destination stations only.
(3) Force destination address to specific ports.
This may be used for two purposes:
a. Allow forwarding to a unicast address, which has
not been learned.
b. Limit forwarding of a multicast address to certain
ports. Note, that this filter will only be applied to
NSR frames.
(4) Limited Multicast of address on filtered port(s) to
specified exit mask of ports.