Nelson's log

Powerline ethernet

I’m spending a few weeks in an apartment in Berlin that’s a large sprawling place. The single wifi router at one end has no hope of reaching the other end and there’s no ethernet in the house. So I took a $50 gamble on a powerline ethernet kit and it seems to work, at least up to 30Mbps. We’ll see if it lasts; my friend says in his experience these things fail after a month or two.

The plug-n-play experience out of the box is pretty great. Plug both devices in, press the pair button, and you’re done. It acts more or less like a bridged ethernet. Plug one end into your router, another end into a computer, and you’re done.

One wrinkle here is security. Your network is being carried out on power lines and who knows how far they’ll go. So the products all have a shared key encryption mechanism (pairing is key exchange) to keep your network private. They probably leak all sorts of RF out the modulated wires, oops.

TP-Link makes a huge variety of these devices. My box says “AV600 TL-PA4020P Kit”, a variant I can’t even find anywhere, but it seems about the same as the AV500 versions only 100Mbps faster. The choices seem to be power passthrough or not, 1-3 ethernet ports per device, and then more expensive for higher bandwidth (up to 1.2Gbps). Different versions for different countries too, both the electrical plug shape and radio frequency interference concerns. Some versions also have a WiFi access point built in, I kind of wish I’d bought one but I wanted to keep it simple and cheap.

The relevant network standard is HomePlug, some vendor consortium for powerline networking. (They just dissolved last year and put all the specs in the public domain.) In theory there’s vendor interoperability. I don’t quite know what’s going on, the Wikipedia article talks about 1000+ channels from 2 to 86MHz.

The really interesting play here is if all your Internet of Things devices supported this kind of networking. Just plug them into the power; no wifi or ethernet required. I wonder why that’s not more popular, I suspect it’s because of the rumored flakiness of powerline ethernet.