Chapter 6 Wireless Lan And Authentication Server; Wireless Lan Overview; Wireless Lan Basics - ZyXEL Communications ZyWALL 5 User Manual

Wireless LAN and Authentication Server
This chapter discusses how to configure Wireless LAN and Auth Server on the ZyWALL.
6.1

Wireless LAN Overview

This section introduces the wireless LAN (WLAN) and some basic scenarios.
6.1.1 Additional Installation Requirements for Using 802.1x
A computer with an IEEE 802.11b wireless LAN card.
A computer equipped with a web browser (with JavaScript enabled) and/or Telnet.
A wireless station must be running IEEE 802.1x-compliant software. Currently, this is offered
in Windows XP.
An optional network RADIUS server for remote user authentication and accounting.
6.2

Wireless LAN Basics

This section provides background information on WLAN.
6.2.1 Channel
A channel is the radio frequency(ies) used by IEEE 802.11b wireless devices. Channels available
depend on your geographical area. You may have a choice of channels (for your region) so you should
use a different channel than an adjacent AP (access point) to reduce interference. Interference occurs
when radio signals from different access points overlap causing interference and degrading
performance.
6.2.2 ESS ID
An Extended Service Set (ESS) is a group of access points or wireless gateways connected to a wired
LAN on the same subnet. An ESS ID uniquely identifies each set. All access points or wireless
gateways and their associated wireless stations in the same set must have the same ESSID.
6.2.3 RTS/CTS
A hidden node occurs when two stations are within range of the same access point, but are not within
range of each other. The following figure illustrates a hidden node. Both stations (STA) are within
range of the access point (AP) or wireless gateway, but out-of-range of each other, so they cannot
"hear" each other, that is they do not know if the channel is currently being used. Therefore, they are
considered hidden from each other.
Wireless LAN and Authentication Server
ZyWALL 5 Internet Security Appliance
Chapter 6
6-1