ZyXEL Communications MWR222 - V1.0 Manual page 271

instead of user-specific credentials. The common-password approach makes
WPA-PSK susceptible to brute-force password-guessing attacks but it's still an
improvement over WEP as it employs an easier-to-use, consistent, single,
alphanumeric password.
User Authentication
WPA or WPA2 applies IEEE 802.1x and Extensible Authentication Protocol (EAP)
to authenticate wireless clients using an external RADIUS database.
If both an AP and the wireless clients support WPA2 and you have an external
RADIUS server, use WPA2 for stronger data encryption. If you don't have an
external RADIUS server, you should use WPA2 -PSK (WPA2 -Pre-Shared Key) that
only requires a single (identical) password entered into each access point,
wireless gateway and wireless client. As long as the passwords match, a wireless
client will be granted access to a WLAN.
If the AP or the wireless clients do not support WPA2, just use WPA or WPA-PSK
depending on whether you have an external RADIUS server or not.
Select WEP only when the AP and/or wireless clients do not support WPA or
WPA2. WEP is less secure than WPA or WPA2.
WPA(2)-PSK Application Example
A WPA(2)-PSK application looks as follows.
First enter identical passwords into the AP and all wireless clients. The
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Pre-Shared Key (PSK) must consist of between 8 and 63 ASCII
characters (including spaces and symbols).
The AP checks each wireless client's password and (only) allows it to
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join the network if the password matches.
The AP derives and distributes keys to the wireless clients.
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The AP and wireless clients use the TKIP or AES encryption process to
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encrypt data exchanged between them.
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