Description: The set of ports to which frames received from a specific port and destined for a specific MAC address, are allowed to be forwarded. Each octet within the value of this object specifies a set of eight ports, with the first octet specifying ports 1 through 8, the second octet specifying ports 9 through 16, etc. Within each octet, the most significant bit represents the lowest numbered port, and the least significant bit represents the highest numbered port. Thus, each port of the bridge is represented by a single bit within the value of this object. If that bit has a value of '1' then that port is included in the set of ports; the port is not included if its bit has a value of '0'.(Note that the setting of the bit corresponding to the port from which a frame is received is irrelevant.). In module 1 (base module), there are 22 100M twisted-pair ports (port 1..22) which is mapped to the PortMap's port 1 to 22 respectively. In module 2 (slot 1 module), there are 2 100M FX/100 TX (or a single port 100M FX) ports which is mapped to the PortMap's port 23, 24 respectively (if the module is a single port 100M FX , it is just mapped to port 23 and port 24 is ignored). Module 3 (slot 2 module) is a single-port Gigabit Ethernet and it is mapped to the PortMap's port 25.