ZyXEL Communications ZyXEL ZyAIR 100 - Manual (Page 77)

ZyWALL 10~100 Series Internet Security Gateway
Wireless LAN Screens 6-1
Chapter 6
Wireless LAN Screens
This chapter discusses how to configure Wireless LAN on the ZyWALL 100, 30W and 10W.
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 client computer 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
IEEE 802.11b wireless devices use ranges of radio frequencies called channels. Choose the radio channel
depending on your geographical area. Adjacent Access Points (APs) should use different channels to reduce
crosstalk. Crosstalk occurs when radio signals from access points overlap and cause interference that
degrades performance.
6.2.2 ESS ID
Extended Service Set (ESS) is defined as one or more APs acting as a bridge between a wired LAN and the
associated wireless clients. The ESS ID is a unique ID given to the APs and the wireless clients that
participate in the same wireless network. You can think of the ESS ID as being similar to a workgroup name
in a Microsoft network.
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