The Next Gen of Powerline Network Adapters

Many systems builders involved in small office, home office (SOHO) networking are aware of the two main choices for building out a network: wired or wireless. But they should also be aware of a third alternative: AC wires--the electrical circuitry that's already inside home and office walls.

AC wires can be accessed anywhere a computer is in use. What's more, with "powerline adapters," systems builders can deploy those AC wires inside the walls to replace Ethernet cable. Working with powerline adapters can free systems builders and their clients from situations where a spot is hard to reach with an Ethernet cable, or when it would be unsightly to use Ethernet cable. Powerline adapters offer systems builders yet another class of product they can confidently resell.

Proprietary versions of powerline adapters have been around for a few decades. Today, a new generation of adapters offers higher speeds, more robust performance and greater interoperability.

Some Choices

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We review four of these new-generation powerline adapters. Three of them use the HomePlug AV specification from San Ramon, Calif.-based HomePlug Powerline Alliance, while the fourth uses a competing spec from Universal Powerline Association (UPA), based in England (see "Plug it in, Plug it in," center). Each adapter is quite small, and each has three indicator lights: One for power, one to detect a data path to another adapter and one to detect a connection to the Ethernet port.

While each adapter is shaped differently, all can be plugged into a standard two-plug outlet without blocking the second plug. But the documentation for all four brands warns against plugging them into surge protectors or uninterruptible power supplies, which would obliterate the signal.

Next: HomePlug UnitsHomePlug Units

The HomePlug AV specification is the latest in a series of HomePlug powerline adapter specifications. On a quiet line, HomePlug AV can get a throughput of 80 Mbps, which is enough to connect multiple HD-TV sets to a digital set-top box.

The HomePlug Powerline Alliance has a Web site listing of products that support the HomePlug AV spec from more than a dozen vendors. The three products listed offer 128-bit Advanced Encryption Standard (AES) encryption, with software that lets you set the encryption key.

Also, in point-to-point connections, all three adapters immediately replaced an Ethernet cable as described. Even when a hair dryer was plugged into the same outlet and turned on, all three adapters continued to function without a hitch.

But when two ports on a router were connected to two adapters so that downstream they were connected to two different computers, the units interfered with each other. Also, response times rose by a factor of 50. When one adapter was plugged into a port on the router, multiple adapters downstream could use the upstream adapter as if it were a router, with the adapters basically creating their own network. In fact, you can use as many as 16 adapters in a network.

The only UPA adapter tested was the HDXB101 from Netgear. In point-to-point use, it behaved much like the HomePlug units, with one difference: A plugged-in and running hair dryer brought the unit to its knees. In fact, once the hair dryer was turned on, response times went up by a factor of about 150.

Netgear states that 16 of the units can network in one circuit, like the HomePlug units. Also, downstream UPA adapters can network to the upstream UPA adapter.

In conclusion, it appears the two specifications shouldn't be mixed. nPlug it In, Plug it In

HomePlug AV Units

• Actiontec Megaplug HPE200AV Ethernet Adapter from Actiontec Electronics. Standard direct-plug. Price: Just under $170 for two-unit kit

• PLK200 PowerLine AV Ethernet Adapter from Linksys (division of Cisco Systems). Direct-plug unit. Price: About $180 for two-unit kit

• PLA-400 Ethernet Adapter from ZyXEL Communications. Uses power cord. Price: About $100 for individual units

UPA Unit

• HDXB101 from Netgear. Direct-plug unit. Price: About $200 for a two-unit set

LAMONT WOOD is a freelance technology writer based in San Antonio.