ZyXEL Communications Corporation G270S Manuel D’Utilisation

ZyXEL G-270S User’s Guide

Chapter 2 Wireless LAN Network

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Figure 9   WPA(2) with RADIUS Application Example

The IEEE 802.11b/g standard describes a simple encryption method between the wireless 
stations and AP. Two encryption types are defined: an Open system mode and a Shared key 
mode.

•  Open system mode is implemented for ease-of-use and when security is not an issue. 

The wireless station and the AP do not share a secret key. Thus the wireless stations can 
associate with any AP and listen to any data transmitted plaintext.

•  Shared key mode involves a shared secret key to authenticate the wireless station to the 

AP. This requires you to enable the wireless LAN security and use same settings on both 
the wireless station and the AP. 

Preamble is used to signal that data is coming to the receiver.  

Short preamble increases performance as less time sending preamble means more time for 
sending data. All IEEE 802.11b/g compliant wireless adapters support long preamble, but not 
all support short preamble. 

Select Long preamble if you are unsure what preamble mode the wireless adapters support, 
and to provide more reliable communications in busy wireless networks. 

Select Long and Short to have the ZyXEL G-270S automatically use short preamble when  
access point/wireless stations support it, otherwise the ZyXEL G-270S uses long preamble. 

Note: The ZyXEL G-270S and the access point/wireless stations MUST use the same 

preamble mode in order to communicate.