Wireless Hacks

Hack 11 HPNA and Powerline Ethernet

These nontraditional networking protocols can save you a ton of effort.

While not wireless networking protocols per se, both HPNA and Powerline Ethernet are finding their way into many people's network scheme. Like wireless, they both provide network functionality without requiring the installation of CAT5 cable. But rather than use wireless, they use other common media for their physical connection.

HPNA

HPNA stands for Home Phone Networking Alliance . It provides networking capabilities over existing CAT3 cable, and can share the same wire as a standard telephone line (even if you are using DSL on the same line). HPNA can reach about 1,000 feet over CAT3. The original HPNA 1.0 products can communicate at about 1.3 Mbps, while the newer HPNA 2.0 standard allows for speeds of up to 32 Mbps (although devices operating at 10 Mbps are more common). Some consumer grade routers, such as 2Wire HomePortal 100W, incorporate Ethernet, HPNA, and 802.11b in one unit.

Pros

• Instant networking in any building with existing telephone wiring.

• Very simple installation; just plug it in and you're done.

• Fairly inexpensive.

Cons

• HPNA isn't nearly as popular as Ethernet or Wireless, so it can sometimes be hard to find in retail stores.

• HPNA 1.0 is much slower than wireless, but HPNA 2.0 approaches speeds of 802.11b.

• Every HPNA device uses the telephone line as a shared medium, making it less efficient than a network switch as more devices are added.

Recommendation

HPNA can be ideal for adding access points to additional locations in a house or building that doesn't have CAT5 Ethernet laid to each room. Dedicated Ethernet is better for speed and reliability, but HPNA can make your job much easier. If you need to add additional access points to a building for greater coverage, or you want to shoot "through" a building by adding a device with external antennas on opposite walls, then HPNA can save a great deal of effort when tying it all together.

Powerline Ethernet

Powerline Ethernet uses AC power lines as a physical medium for network traffic. Powerline devices are about as simple as they come; simply plug in a CAT5 cable to one side of the device, plug the other end into any wall outlet, and you should be up and running. Some devices support encryption on the devices, but this is hardly ever necessary. Powerline Ethernet won't cross a power transformer, so your network signal usually stops at the end of your house wiring.

Siemens, Linksys, and NetGear all make popular Powerline adapters that should interoperate well with each other. They advertise speeds of up to 14 Mbps, but actual data rates of 5 or 6 Mbps are typical. As with HPNA, Powerline is a shared medium, much like a networking hub. More devices means more possible collisions and lower throughput.

Pros

• Very simple installation, with virtually no configuration needed.

• Data speeds comparable to 802.11b.

• Ethernet bridges mean no configuration at all on the computer side.

Cons

• Slightly expensive as of this writing (typically $100 per device, with at least two devices required).

Recommendation

Much like HPNA, Powerline Ethernet can be ideal in situations where CAT5 wiring just isn't practical. This can make installation much simpler whenever you have an AC outlet handy but can't quite get to a telephone line or CAT5 cable. There is no configuration needed in most cases, as the Powerline bridge acts just like a network hub to your Ethernet devices.

While CAT5 is usually preferred over line-sharing protocols such as HPNA and Powerline, these devices can save you a tremendous amount of installation time and effort. If you can cope with the slower data rates and slightly higher cost (compared to Ethernet), then these devices might be a perfect component for your wireless networking project.