SIGNAL INTERFERENCE ISSUES

All network topologies face a risk of interference with the signal, causing a cessation of communication or an agonizingly slow rate of communication. As you expand your network and try to fit more stuff into your rooms and walls and along your cable runs, you might inadvertently cause yourself some problems.

WIRELESS INTERFERENCE

Wireless networks have the greatest risk of interference because RF technology swirls around the room, potentially bumping into other RF devices. Cordless telephones and microwave ovens are the two most common causes of interference problems because they use the same 2.4GHz frequency band as your wireless network.

However, beyond frequency interference, wireless communications experience interference from metallic objects in your home. Metal furniture, metal studs, nails, foil-backed insulation, and even lead paint can reduce the speed and distance of a wireless signal. In addition, high-density materials such as concrete and plaster are more difficult to penetrate and absorb some of the signal's energy, shortening the distance the signal travels. Porous materials such as wood or drywall are more "wireless friendly."

You can overcome most interference problems by moving your devices around the room, or the house, until you reach acceptable levels of speed and distance. Also, try testing the signal by manipulating the antennas on access points, including your wireless router (are you old enough to remember television rabbit ears, which we spent hours bending and twisting until the reception was acceptable?). In addition, depending on the placement of your devices, you might want to experiment with directional antennas to replace the multidirectional antennas that came with your wireless devices.

ETHERNET INTERFERENCE

Ethernet cable runs into interference if it's too close to fluorescent fixtures, and many computer experts insist that running Ethernet cable too close to electric lines within the wall can also interfere with the data signals. There are also reports that ham radio transmissions can interfere with Ethernet communications because they use the same frequencies.

POWERLINE INTERFERENCE

Any equipment that filters or monitors electrical signals can cause interference with powerline data transmissions and cause slower performance. These devices include uninterruptible power supplies (UPS) or surge protectors. In addition, some older wiring (e.g., knob and tube) degrades performance.

PHONELINE INTERFERENCE

Some performance degradation can occur if the connection from the network adapter is in a splitter rather than a jack (use the empty RJ11 connector in the adapter to plug in telephone instruments). If you're using a DSL modem and the line is split back at the telephone company's central office instead of at your house, you probably have filters for telephone jacks that have telephone instruments attached. Do not connect a phoneline network adapter to one of those splitters; the data signal won't get past it.