This read-write attribute chooses whether IP-related filtering on the ComPort applies only upstream, only downstream, or in both directions, defaulting to bothDirections. It lets an admin scope filtering precisely, for instance allowing downstream multicast video through unimpeded while still filtering upstream chatter, instead of an all-or-nothing approach. For example, an operator wanting to preserve downstream multicast video delivery while still filtering unwanted upstream IP traffic would set stuFiltIpDirectCntrl to upstreamOnly.