Abstract: A method and apparatus for filtering data packets in a shared-medium or point-to-multipoint communications network. A filter unit is sent a data packet carrying a filter tag value in a packet addressed to the filter unit. The value is stored in the filter unit and subsequently received packets not addressed to the filter unit itself are forwarded only if they carry the stored filter tag. An embodiment of particular interest applies the method to Ethernet frames over a telecommunications access network (including optical or wireless networks), and uses the VLAN tag field to carry the filter tag information.