The Black Box Ethernet Extenders provide high-speed LAN connections between peered Ethernet LANs, remote PCs, or any other network-enabled 10/100Base-T device. Operating in pairs, one Ethernet Extender is configured as the (L) Local unit located at one end of the LAN extension and the other Ethernet Extender is configured as the (R) Remote unit at the other end. The Ethernet Extender is configured as a L or R via the switch on the bottom of the unit. These units can automatically forward LAN broad-casts, multicasts, and frames across a 2-wire voice-grade twisted-pair or BNC link. The data is passed transparently (unmodified) through the Ethernet Extenders. The Ethernet Extenders automatically add and delete MAC addresses, only passing pack-ets across the line link that are meant for the remote peered LAN.