A method being performed by a switch connectable to a first network via a network interface and to a Customer Premises equipment, CPE, addressable by a first Medium Access Control, MAC, address via an interface of a first type, the method comprising: receiving, via the interface of the first type, a first unicast frame from the CPE, the first unicast frame having a destination address that is a second MAC address associated with the first network; and receiving, via the network interface, a second frame from the first network, the second frame having a destination address that is the first MAC address; characterized in that: the first network is an Open System Interface, OSI, Layer-2 Ethernet bridged network that uses MAC address-based routing, and the method further comprising: marking the first unicast frame as a first interface frame by placing an indication in the first unicast frame that the frame is a frame received via an interface of the first type: forwarding (78, 98) the first unicast frame to the first network as a marked frame; responsive to the second frame being a unicast frame that comprises the indication that the frame is a frame received via an interface of the first type, discarding the second frame; and responsive to the second frame being a non-unicast frame or not being a unicast frame that comprises the indication that the frame is a frame received via an interface of the first type, forwarding (78, 98) the frame to the CPE via the first type interface. receiving, via the interface of the first type, a first unicast frame from the CPE, the first unicast frame having a destination address that is a second MAC address associated with the first network; and receiving, via the network interface, a second frame from the first network, the second frame having a destination address that is the first MAC address; characterized in that: the first network is an Open System Interface, OSI, Layer-2 Ethernet bridged network that uses MAC address-based routing, and the method further comprising: marking the first unicast frame as a first interface frame by placing an indication in the first unicast frame that the frame is a frame received via an interface of the first type: forwarding (78, 98) the first unicast frame to the first network as a marked frame; responsive to the second frame being a unicast frame that comprises the indication that the frame is a frame received via an interface of the first type, discarding the second frame; and responsive to the second frame being a non-unicast frame or not being a unicast frame that comprises the indication that the frame is a frame received via an interface of the first type, forwarding (78, 98) the frame to the CPE via the first type interface. forwarding (78, 98) the first unicast frame to the first network as a marked frame; responsive to the second frame being a unicast frame that comprises the indication that the frame is a frame received via an interface of the first type, discarding the second frame; and responsive to the second frame being a non-unicast frame or not being a unicast frame that comprises the indication that the frame is a frame received via an interface of the first type, forwarding (78, 98) the frame to the CPE via the first type interface.