Multiplexed packet local area networking using an Ethernet physical layer device. In one embodiment, a network device having dual port Ethernet physical layer devices can be configured to receive a packet on a first Ethernet port. The network device can extract first packet data that is destined for the network device from the data section of the packet and insert second packet data that is destined for the gateway node into the packet to produce a modified packet. The modified packet is then transmitted by the network device over a second Ethernet port.