This INTEGER (groupA/groupB/groupC) assigns the sub-port to one of three private forwarding groups, which, per the virtual switch's group policy objects described later in this MIB, governs whether this sub-port can forward traffic directly to other sub-ports in the same or different groups. It is the classic mechanism for preventing customers on a shared access switch from seeing each other's traffic while still allowing all of them to reach a shared uplink. Placing several residential customer sub-ports all in groupA so they cannot forward to each other directly, while an ISP's uplink sub-port sits in a group whose policy allows it to reach everyone, is a typical deployment.