This value defines, as a port bitmap, which ports within a legacy private VLAN are promiscuous (able to communicate with any other port in that VLAN), with all other, non-promiscuous ports in the VLAN automatically added to the isolation list per the source description. A network administrator sets this to designate uplink or gateway ports that need full reachability, while all other ports in that private VLAN become isolated from each other by default. For example, setting zyLegacyPrivateVlanPromiscuousPorts to a bitmap covering only port 24 on VLAN 50 makes port 24 reachable from every other port in that VLAN, while those other ports can't reach each other directly.