By Andrew Garcia  |  Posted 2006-11-20 Print this article Print

Netgears Powerline HD Ethernet Adapters make a fine alternative to wireless networking equipment, although users may need to test several different outlets to maximize performance.

The Powerline HD Ethernet Adapters (HDX101) extend an Ethernet network over a buildings electrical circuits using DS2s 200M-bps Powerline Communications integrated circuits. With the HDX101 solution, users can deploy multiple adapters throughout a building, providing networking to as many as 16 locations—as long as all outlets are behind the same power meter.

During tests, eWEEK Labs found that throughput and latency varied greatly depending on where we deployed each HDX101 adapter. (A pair of HDX101 adapters costs $250; a single adapter costs $130.)

To maximize throughput, we connected each adapter to a separate socket in the same outlet. Under these ideal circumstances, we were able to realize about 63M bps of real unidirectional throughput and 91M bps of bidirectional traffic. (We measured performance using Ixias IxChariot 6.25.)

However, as we moved the adapters to different outlets throughout the building, performance started to vary wildly, ranging anywhere from 4M bps to 30M bps depending on where we deployed the adapters. Performance also will depend greatly on the health of the buildings electrical circuits (for example, their age and whether they were deployed in different stages), as well as on the types of devices drawing power.

In practical terms, we were able to use the Netgear system to stream a high-definition television broadcast over the power-line network without hiccups in most locations of our test facility, although interference on the electrical circuit did cause occasional problems.

Whenever you turn on an electrical device, it changes the dynamics of the power-line network. We tested the Netgear solution with a hair dryer turned on, and we noticed an immediate 30 percent decrease in performance.

DS2s chip set includes several kinds of error correction—including frequency selection—to move away from spectrum with poor signal-to-noise ratio, so performance normalized within a few minutes. However, performance remained unpredictable until we turned off the hair dryer.

We did find that plugging the hair dryer into a surge protector reduced the amount of noise on the electrical circuit, leading to more stable network performance. We would advise users to seek out electric devices with heavy power draw throughout the building and confirm they are connected to a surge protector to ensure the stability of the HDX101-enabled network.

Filters are the enemy of power-line technology. The buildings power meter acts as a filter that blocks the networkable frequencies, keeping the transmissions localized and away from prying eyes. However, surge protectors and universal power supplies also filter the circuit, so we needed to connect the adapters directly to the wall to establish a link between them.

The adapters come with configuration software that allowed us to name our network, enable support for legacy power-line equipment and set QOS (quality of service) policies for the network.

We were able to use several different QOS algorithms, including TOS (type of service) and 802.1p, or we could dictate a preference (either source or destination) for specific UDP (User Datagram Protocol) or TCP ports.

DS2 officials claim the Netgear implementation supports as many as up to 32 MAC (media access control) addresses, which will allow users to install a Fast Ethernet switch to provide networking to multiple devices in one location.

Technical Analyst Andrew Garcia can be reached at andrew_garcia@ziffdavis.com.

Next page: Evaluation Shortlist: Related Products.

Andrew cut his teeth as a systems administrator at the University of California, learning the ins and outs of server migration, Windows desktop management, Unix and Novell administration. After a tour of duty as a team leader for PC Magazine's Labs, Andrew turned to system integration - providing network, server, and desktop consulting services for small businesses throughout the Bay Area. With eWEEK Labs since 2003, Andrew concentrates on wireless networking technologies while moonlighting with Microsoft Windows, mobile devices and management, and unified communications. He produces product reviews, technology analysis and opinion pieces for eWEEK.com, eWEEK magazine, and the Labs' Release Notes blog. Follow Andrew on Twitter at andrewrgarcia, or reach him by email at agarcia@eweek.com.

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