A mechanism is provided by which a hardware filter on a border router of a wireless personal area network is not overloaded by increasing the probability that the hardware filter will capture all the nodes not on the corresponding WPAN. Network addresses for nodes within a subnet are allocated to have the same multicast address hash value in order to permit router multicast filtering to occur within hardware. Hardware filtering thereby relieves the router processor from performing filtering tasks, reducing resource consumption and decreasing the time used to perform filtering. Embodiments provide this functionality by assigning a unique multicast filter register value to each subnet within a network and allocating network addresses associated with that multicast filter register value through either DHCP or SLAAC address generation.