Wi-Fi may be the most popular networking technology, but sometimes even the fastest wireless connection just doesn’t hack it. Perhaps the signal can’t get to the farthest reaches of your home or office, or maybe there are so many wireless networks competing for limited bandwidth that the Netflix movie you’re streaming keeps freezing or stuttering.
Ethernet is still the gold standard for wired networks, but few people have the cabling built into their walls, and even fewer are willing to tear up their walls to install it. Fortunately, you probably already have all the infrastructure you need to set up a wired network: The electrical circuitry in most homes and small offices can do the job. All you need to set up a power-line network are small adapters that plug into any wall outlet and connect via a cable to the Ethernet port of a network device.
Welcome to the world of power-line networking!
Standards are great, there’s so many to choose from!
The whole idea of a standard is that everything that complies with a given standard should work the same way and work together. Wouldn’t that be nice? In the real world, there are not only multiple competing standards, but standards sometimes fork, fragment, and splinter. Wired and wireless Ethernet technology is a relatively settled space. The same cannot be said for power-line Ethernet networking, especially not internationally.
The U.S. has largely settled on the IEEE P1901 standard for power-line networking, with the HomePlug Powerline Alliance trade group handling certification under the HomePlug brand. But the HomePlug Alliance departed from the IEEE standard to create its latestpower-line networking technology, HomePlug AV2. A spokesperson from the alliance told me the group saw no benefit in going through the admittedly time-consuming and often politically tricky IEEE standards development process this time around
A related standard, IEEE P1905.1, marketed under the nVoy brand is used for hybrid home networks that rely on a combination of Wi-Fi, power-line, and MoCA (Multimedia over Coax, which is the cable that cable-TV companies rely on). If all that isn’t confusing enough, there are competing standards from a different international standards body (the ITU) for both power-line (HomePNA) and hybrid networks (G.hn).
Our best advice when deploying power-line networking products? Stick with the same standard and buy everything from one vendor. If you want to understand the ins and outs of the various power-line standards, read on.
The HomePlug standards
The HomePlug Alliance has developed three generations of HomePlug specifications. The original HomePlug standard, announced in 2001, supports physical network speeds of up to 14 megabits per second (although, as with most networking standards, real-world speeds fall considerably short of this theoretical maximum). Later products are backwards compatible with HomePlug 1.0, but manufacturers have moved on to faster successors: HomePlug AV and HomePlug AV2. Unfortunately, it’s not always easy to tell which standard products are based on.
HomePlug AV, announced in 2005, supports theoretical speeds of up to 200 Mbps, but most current HomePlug AV products feature proprietary enhancements that raise the theoretical speed to 500 or 600 Mbps. HomePlug AV2, ratified in early 2012, supports speeds ranging from 500 Mbps to 1200 Mbps; but the faster speeds are offered only by products equipped with optional enhancements in the AV2 spec.
The even faster version of AV2 is called HomePlug AV2 MIMO (Multiple Input/Multiple Output). It uses all three wires in an electrical circuit: Hot, neutral, and ground. It necessarily requires power cords ending in three prongs and AC outlets that can accommodate them. Many older homes (in the U.S., those built before 1962) don’t have ground wires in their walls and won’t benefit from this standard.
The products we tested are based on the HomePlug AV 500, AV2 and AV2 MIMO standards. In our tests, there wasn’t much difference in performance between the AV 500 and AV2 products, but the lone AV2 MIMO kit (provided by ZyXEL) proved almost twice as fast as the others. It was also more than twice as expensive as any of the other kits.
Note that the HomePlug Alliance does not certify so-called HomePlug AV 500 or AV 600 products for interoperability. If you use HomePlug AV adapters from different vendors, you’re only assured basic HomePlug AV speeds of up to 200 Mbps.
With HomePlug AV2, however, the Alliance is certifying both the basic 600 Mbps version and the 1200 Mbps MIMO version. Obviously there’s potential for confusion over the basic and enhanced AV2 specs, not to mention the HomePlug AV 500/600 products in the market. If you only pay attention to the claimed performance, it’s almost impossible to tell whether you are getting an enhanced HomePlug AV product or a basic HomePlug AV2 product, since you’ll see both numbers (500 Mbps and 600 Mbps) on both types of adapters.
Most vendors put a HomePlug logo on their packaging, but that generic logo doesn’t indicate the version of the technology inside. The HomePlug Alliance could learn some lessons about branding from the Wi-Fi Alliance, which has clear markings for the old 802.11b through the latest 802.11ac standards. And since some of the enhanced HomePlug AV products were actually faster than the AV2 products, figuring out which you have won’t matter so long as you stick with products from the same vendor.
Setting up a HomePlug network
Because most people contemplating a wired home network already have a Wi-Fi network, vendors have made it easy to create hybrid Wi-Fi/HomePlug networks using your existing router by offering starter kits with two adapters. (All of the products in this review were such kits.)
The adapters are typically no larger than a small night light. Again, they plug directly into any available wall outlet, but some of the larger ones block the second outlet. Each adapter has one gigabit Ethernet port so you can connect it via Etherent cable to your router or switch at one end, and to a client device or switch at the other end.
Whatever you do, don’t plug HomePlug adapters into power strips that have built-in surge suppressors. The surge suppression will effectively filter out the signals carrying your data, rendering the adapter slow or completely non-functional.
HomePlug networks require no setup. When you plug in the network device, it should be connected within moments. Also, most current products have built-in encryption so that your network signal can’t be detected by someone else on the same power grid. You might, however, need to provide a password (using a utility on a PC) to add additional adapters, especially if you’re mixing adapters from different manufacturers.
While HomePlug products should work in most locations, you might run into problems in buildings with very old wiring. The HomePlug Powerline Alliance has also found some rare instances of incompatibility with AFCI (arc-fault circuit interrupters) circuit breakers. The national electrical code requires AFCI breakers to service the AC outlets in the bedrooms of newer homes.
How we tested HomePlug adapters
To evaluate the performance of the HomePlug starter kits reviewed here, I measured TCP throughput and streamed a high-definition movie. For the TCP measurements, I connected each HomePlug adapter to a free LAN port on my router in the living room area of my loft, and I connected a Windows 8 notebook to another free LAN port to function as a server. I then connected a second Windows 8 notebook to a second HomePlug adapter plugged into a wall outlet in the mezzanine of our loft. I installed JPerf (a Java-based user front end for IPerf) on both notebooks.
I also streamed a high-def movie from the downstairs (server) notebook to the upstairs notebook using iTunes’ home sharing feature. While this test is anecdotal at best, it confirmed that each of the kits tested was capable of streaming high-def video.