The set of ports to which frames received from a
specific port and destined for a specific Multicast or
Broadcast MAC address must be forwarded, regardless of
any dynamic information e.g. from GMRP. A port may not
be added in this set if it is already a member of the
set of ports in portBaseStaticMulticastForbiddenEgressPorts.
The default value of this object is a string of ones of
appropriate length.