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Frequently Asked Questions

What is ad-hoc mode?

When a wireless network is set to ad-hoc mode, the wireless-equipped computers are configured to

communicate directly with each other. The ad-hoc wireless network will not communicate with any wired

network.

What is infrastructure mode?

When a wireless network is set to infrastructure mode, the wireless network is configured to communicate with

a wired network through a wireless access point.

What is roaming?

Roaming is the ability of a portable computer to communicate continuously while moving freely throughout an

area greater than that covered by a single access point. Before using the roaming function, the user must make

sure that the computer uses the same channel number that is used by the access point of the dedicated

coverage area.

To achieve true seamless connectivity, the wireless LAN must incorporate a number of different functions. Each

node and access point, for example, must always acknowledge receipt of each message. Each node must

maintain contact with the wireless network even when not actually transmitting data. Achieving these functions

simultaneously requires a dynamic RF networking technology that links access points and nodes. In such a

system, the user’s end node undertakes a search for the best possible access to the system. First, it evaluates

such factors as signal strength and quality, as well as the message load currently being carried by each access

point and the distance of each access point to the wired backbone. Based on that information, the node next

selects the right access point and registers its address. Communications between end node and host computer

can then be transmitted up and down the backbone.

As the user moves on, the end node’s RF transmitter regularly checks the system to determine whether it is in

touch with the original access point or whether it should seek a new one. When a node no longer receives

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Appendix A: Troubleshooting

Frequently Asked Questions

acknowledgment from its original access point, it undertakes a new search. Upon finding a new access point, it

then re-registers, and the communication process continues.

What is ISM band?

The FCC and their counterparts outside of the U.S. have set aside bandwidth for unlicensed use in the ISM

(Industrial, Scientific and Medical) band. Spectrum in the vicinity of 2.4 GHz, in particular, is being made

available worldwide. This presents a truly revolutionary opportunity to place convenient high-speed wireless

capabilities in the hands of users around the globe.

What is Spread Spectrum?

Spread Spectrum technology is a wideband radio frequency technique developed by the military for use in

reliable, secure, mission-critical communications systems. It is designed to trade off bandwidth efficiency for

reliability, integrity, and security. In other words, more bandwidth is consumed than in the case of narrowband

transmission, but the trade-off produces a signal that is, in effect, louder and thus easier to detect, provided that

the receiver knows the parameters of the spread-spectrum signal being broadcast. If a receiver is not tuned to

the right frequency, a spread-spectrum signal looks like background noise. There are two main alternatives,

Direct Sequence Spread Spectrum (DSSS) and Frequency Hopping Spread Spectrum (FHSS).

What is DSSS? What is FHSS? And what are their differences?

Frequency-Hopping Spread-Spectrum (FHSS) uses a narrowband carrier that changes frequency in a pattern

that is known to both transmitter and receiver. Properly synchronized, the net effect is to maintain a single

logical channel. To an unintended receiver, FHSS appears to be short-duration impulse noise. Direct-Sequence

Spread-Spectrum (DSSS) generates a redundant bit pattern for each bit to be transmitted. This bit pattern is

called a chip (or chipping code). The longer the chip, the greater the probability that the original data can be

recovered. Even if one or more bits in the chip are damaged during transmission, statistical techniques

embedded in the radio can recover the original data without the need for retransmission. To an unintended

receiver, DSSS appears as low power wideband noise and is rejected (ignored) by most narrowband receivers.

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What is WEP?

WEP is Wired Equivalent Privacy, a data privacy mechanism based on a shared key algorithm, as described in the

IEEE 802.11 standard.

What is WPA?

WPA is Wi-Fi Protected Access, a wireless security protocol that can be used in conjunction with a RADIUS

server.

What is a MAC Address?

The Media Access Control (MAC) address is a unique number assigned by the manufacturer to any Ethernet

networking device, such as a network adapter, that allows the network to identify it at the hardware level. For all

practical purposes, this number is usually permanent. Unlike IP addresses, which can change every time a

computer logs onto the network, the MAC address of a device stays the same, making it a valuable identifier for

the network.

How do I reset the Router?

Press the Reset button on the back panel for about five seconds. This will reset the Router to its default settings.

How do I resolve issues with signal loss?

There is no way to know the exact range of your wireless network without testing. Every obstacle placed

between the Router and a wireless PC will create signal loss. Lead glass, metal, concrete floors, water and walls

will inhibit the signal and reduce range.

Start with the Router and your wireless PC in the same room and move

it away in small increments to determine the maximum range in your environment.

You may also try using different channels, as this may eliminate interference affecting only one channel.

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I have excellent signal strength, but I cannot see my network.

Wireless security is probably enabled on the Router, but not on your wireless adapter (or vice versa). Verify that

the same wireless security settings are being used by all devices in your wireless network.

How many channels/frequencies are available with the Router?

There are eleven available channels, ranging from 1 to 11 (in North America).

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Appendix B: Wireless Security

Security Precautions

Appendix B: Wireless Security

Linksys wants to make wireless networking as safe and easy for you as possible. The current generation of

Linksys products provide several network security features, but they require specific action on your part for

implementation. So, keep the following in mind whenever you are setting up or using your wireless network.

Security Precautions

The following is a complete list of security precautions to take (at least steps 1 through 5 should be followed):

1.

Change the default SSID.

2.

Disable SSID Broadcast.

3.

Change the default password for the Administrator account.

4.

Enable MAC Address Filtering.

5.

Change the SSID periodically.

6.

Use the highest encryption algorithm possible. Use WPA if it is available. Please note that this may reduce

your network performance.

7.

Change the WEP encryption keys periodically.

For information on implementing these security features, refer to “Chapter 6: Configuring the Router.”

NOTE:

Some of these security

features are available only

through the network router or

access point. Refer to the

router or access point’s

documentation for more

information.