The idea is simple: Use your existing electrical wiring to create a local area network for your PCs, Macs, Linux boxes, or other network-enabled devices. To do this, you connect your network devices to special, safe, electrical-socket adapters that convert the standard Ethernet data into very high frequency signals that ride over standard electrical wiring.
This doesn't affect the wires' ability to carry power: The powerline network signals are in the 4- to 21-MHz range, enormously far away from the power grid's normal operating frequency of 50 hertz or 60 hertz. In this way, an electrical system can simultaneously deliver power and data over the same wires: Powerline networking devices can see and decode the networking signals, but standard electrical devices -- lights, motors, etc. -- don't even know the network data signals are there, and continue to operate normally.
This isn't theoretical: Powerline networking devices have been around for years, but remained on the fringes due to problems of interoperability and high cost. However, recent standardization efforts and aggressive price cuts have made powerline networking easy, affordable, and worth a serious look by anyone seeking to add or extend a network within a small business, enterprise workgroup, or home office.
Powerline networking has two enormous advantages over traditional wired networking. First and foremost, like wireless networking (a form of radio), a powerline network requires no new cables or special wiring: Any building that has normal electrical service already is wired for powerline networking, with no need to snake cables through walls or under floors, and with no need for drilling or other structural work.
Second, and again like wireless networking, powerline networking spreads the signal around: Once the network signal is injected at any point into a wiring system, the network can be accessed from almost anywhere on the same electrical system. This means you can move from room to room or floor to floor in a building, and still be able to access the powerline network from any ordinary wall socket. In fact, because electrical wires carry signals very well, a powerline node actually can have greater range than a wireless access point, and also avoid many of the problems of wireless signal loss caused by thick walls or other obstructions. Anywhere the electrical wires go, the powerline networking signal follows.
There's a third major advantage of powerline networking because its signals stay within the wires: Unlike wireless networking, which creates a wide bubble of connectivity in which anyone, authorized or not, may be able to detect the network and try to log in, a powerline network's data signal remains confined to the physical wires: It doesn't broadcast into the surrounding empty space. This means a potential electronic eavesdropper can't drive by on the street or sit in the parking lot and hack a powerline network, for example. Practically speaking, the only way to access a powerline network is to have physical access to an electrical outlet that's part of the network. In this sense, powerline networking can be more secure than wireless networking. In fact, security issues are worth a closer look.
You may be thinking: If a powerline network signal follows the wires, doesn't that mean that the network traffic gets broadcast across the entire regional electrical network? The answer's no: Powerline networking data signals cannot pass unchanged through electrical transformers. This means in most buildings, the powerline network data signals become unreadable at the point where the building connects to the regional power grid -- usually beneath the street or on a utility pole in front of the building.
If you're the sole occupant of the building, the transformer effectively isolates your data from wider distribution, so people down the street (for example) can't read your powerline network data, and you can't read theirs. Thus, powerline networking gives you a reasonable degree of intrinsic security.
But there's a catch: If you're in an office complex, apartment building, condo, or other situation where a number of different occupants all may be on "your" side of the electrical transformer, then they could, in theory, see your data stream, if they plugged an appropriate powerline networking device into their wall socket.
To counter this, most of the current generation of powerline networking adaptors use automatic on-the-fly data encryption (usually 56-bit DES) and other methods to prevent unauthorized network access. For example, the powerline devices may limit access only to other devices whose serial numbers, media access control ("MAC") numbers or other unique identifiers are known to the network administrator. (And these security options are on top of whatever intrinsic security -- passwording, software access permissions, and such -- that's incorporated into the network itself.) The end result is security at least as good -- and, I think, often better -- than that of many wireless networks.
Two Major Styles
Powerline networking devices come in two major flavors, exemplified by the Siemens SpeedStream Powerline series and Phonex Broadband Corp.'s NeverWire family. Both can work with almost any Ethernet-enabled device. Both offer 56-bit DES encryption, plug-and-play setup, intrinsic maximum speeds of about 14 Mbps, and can bridge to any normal 10/100-Mbps Ethernet network. (Full specs are available via the above links.) But beyond these basics, the units differ:
The Speedstream units are "zero footprint" devices (no desk or shelf space needed) roughly the size and shape of a power brick: about 4" high by 2.5" wide by 1.5" thick (approximately 10 centimeters by 6.5 centimeters by 4 centimeters). Setup is extremely simple: Plug one Speedstream unit into a plain-vanilla wall socket anywhere, and connect it to a PC's network card or to a network hub using a standard RJ45 network cable. (Siemens also offers units that connect to a PC via a USB cable.) Repeat the process at a second location with a second PC or hub. That's it; you're done -- a basic network now exists between the PCs or hubs, using the intervening electrical wiring to carry the signals. No special software or drivers are needed, and no special configuration. To go beyond the basics -- say, if you want enhanced security (a good idea) -- you then load special software onto the PCs that connect to the powerline devices, and use that to set unique passwords and permissions for the powerline network devices. The same software also helps troubleshoot any problems that may occur; and the setup CD contains still more tools and information to help get the powerline network going with just about any PC configuration. (But I needed none of this in my tests: The Siemens units worked right out of the box, with no special setup needed for basic networking.) The Siemens units retail for about $90; you need at least two units to set up a powerline network.
The NeverWire units are larger than Speedstream's; or about the size of a standard freestanding external cable modem: roughly 6.5" high x 1.5" wide x 5.5" deep (call it 16.5 centimeters by 4 centimeters by 5.5 centimeters). As such, they're less portable than the Siemens units. On the other hand, they are even easier to set up because all the important features -- including troubleshooting and enhanced security -- are available via push-button controls built into the units. These extra controls mean you don't need extra software or a PC to set up even the NeverWire's advanced features. This is particularly useful if any portion of your powerline network will connect to a hub instead of to a PC; you can fully set up and configure the unit using only the built-in control panel. Beyond this key difference, the NeverWire units are much the same as the SpeedStream; they even cost roughly the same; with most retail outlets selling them for around $100 per unit (you need at least two to create a network), but with some retailers offering them for $80 each.
To me, the small SpeedStream-style units seem ideal in situations where portability or ad hoc networking is key. For example, if you have a notebook that you want to carry from room to room, or if your powerline networking setup is temporary, the small size, zero footprint, and easy transport of the SpeedStream units may make them the better choice.
On the other hand, the NeverWire-style units seem better suited for permanent or semi-permanent installation. In these cases, the NeverWire's self-contained, software-less setup and operation is a plus, and the slightly larger size is less important.
Note that in addition to creating new networks from scratch, both types of units can be used to extend an existing network: For example, if building geometry or local interference prevents easy coverage of an area via a wireless node, a powerline network can send the network data to any location served by the building's electrical system -- including deep basements, the building core, or other areas where a radio signal just won't go. At the remote location, you can even switch back to wireless via a simple hub and standard wireless access point. Siemens even offers a combo powerline/wireless access point that connects wireless devices to the powerline network in one step. Either way, the powerline network acts as a transparent link between two otherwise disconnected wireless bubbles.
My office uses a mix of networking media, including standard 10/100-Mbps RJ45 cabling, older-style 10-Mbps BNC coaxial cabling, and a wireless node. I rarely use the wireless node because it's been hard to set up and maintain, and because I have serious concerns about wireless security. (The latter affects the former: it's relatively easy to get a wireless connection going, but it's considerably harder to establish and maintain a truly secure wireless connection.)
Adding the powerline nodes to my network took only minutes with both the SpeedStream and NeverWire units; and I barely had to refer to the manuals. In both cases, establishing a secure connection was impressively hassle-free -- and vastly simpler than setting up a secure wireless node.
The speed of both brands of powerline units was roughly equivalent to a standard 10 Mbps network connection, or to a standard wireless connection when the wireless node has excellent signal strength. And despite the presence of a number of portable phones, quartz-halogen lights on dimmer circuits, and other devices that can sometimes cause interference in the frequency range used by powerline devices, I never noticed any speed decay or increased error rates. In routine use, powerline networking "felt" solid and just as fast as any other kind of networking in the 10-Mbps speed class.
I'm very impressed with powerline networking, and I'm not the only one. (See, for example, Dave Strom's Web Informant article.) I've even made powerline networking a permanent part of my office setup. For me, it's effectively replaced my wireless node. In fact, I think powerline networking is worth a serious look by anyone seeking to add or extend networking for PCs, Macs, Linux boxes, or any other network-capable devices within a small business, workgroup, or home.
What's your take? Have you tried powerline networking? Have your experiences been positive or negative? Do you feel that powerline networking's better security is worth the inconvenience of being "tethered" to a power outlet, or does the total freedom of mobility of wireless networking make the lower security worthwhile? Join in the discussion!