The Westermo DDW-220 is an Ethernet extender enhanced with a built-in four port Ethernet switch which allows this one unit to be used to create entire Ethernet solutions. Existing twisted pair cables can be used to establish a high speed remote connection between two Ethernet networks. With transfer rates up to 5.7 Mbits/s and with an operating distance of up to 10 kilometres at lower data rates, this is an easy-to-install alternative to fibre optic or radio systems when linking remote Ethernet networks. The DDW-220 uses a transient blocking unit on each DSL line to provide both over-current and over-voltage protection on the line allowing it to handle indirect lightning strike transients, power induction and short circuit problems.

By design, a standard Ethernet network is limited to a 100m distance for point-to-point transmissions over copper cables. For greater distances standard UTP Ethernet cable can not be used. To create a high-speed link between two distant Ethernet networks, an extender is necessary. The DDW-220 combines the functions of an extender using any twisted pair cables (rather than expensive optical fibres or radio links) and a switch. This ‘’Plug-and-Play’’ unit covers many applications offering data rates from 192 Kbit/s to 5.7 Mbit/s in both directions over distances of up to 10 Km (railway signalling, on board or on track, tunnels, highways, harbours, power stations, extended industrial plants...).