ZyXEL N4100 Betriebsanweisung

Appendix D Wireless LANs

N4100 User’s Guide

authentication. These two features are optional and may not be supported in all 
wireless devices.

Key caching allows a wireless client to store the PMK it derived through a 
successful authentication with an AP. The wireless client uses the PMK when it tries 
to connect to the same AP and does not need to go with the authentication 
process again.

Pre-authentication enables fast roaming by allowing the wireless client (already 
connecting to an AP) to perform IEEE 802.1x authentication with another AP 
before connecting to it.

A wireless client supplicant is the software that runs on an operating system 
instructing the wireless client how to use WPA. At the time of writing, the most 
widely available supplicant is the WPA patch for Windows XP, Funk Software's 
Odyssey client. 

The Windows XP patch is a free download that adds WPA capability to Windows 
XP's built-in "Zero Configuration" wireless client. However, you must run Windows 
XP to use it. 

To set up WPA(2), you need the IP address of the RADIUS server, its port number 
(default is 1812), and the RADIUS shared secret. A WPA(2) application example 
with an external RADIUS server looks as follows. "A" is the RADIUS server. "DS" is 
the distribution system.

The AP passes the wireless client's authentication request to the RADIUS server.

The RADIUS server then checks the user's identification against its database and 
grants or denies network access accordingly.

A 256-bit Pairwise Master Key (PMK) is derived from the authentication process by 
the RADIUS server and the client.