X-Micro Tech. XWL-11GRTX Manual Do Utilizador

 

 

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buffered frames at the access point). 

 

4.13  What is Preamble Type?   

There are two preamble types defined in IEEE 802.11 specification. A long 

preamble basically gives the decoder more time to process the preamble. All 

802.11 devices support a long preamble. The short preamble is designed to 

improve efficiency (for example, for VoIP systems). The difference between the 

two is in the Synchronization field. The long preamble is 128 bits, and the short is 

56 bits.   

 

4.14  What is SSID Broadcast?   

Broadcast of SSID is done in access points by the beacon. This announces your 

access point (including various bits of information about it) to the wireless world 

around it. By disabling that feature, the SSID configured in the client must match 

the SSID of the access point. 

 

Some wireless devices don't work properly if SSID isn't broadcast (for example 

the D-link DWL-120 USB 802.11b adapter). Generally if your client hardware 

supports operation with SSID disabled, it's not a bad idea to run that way to 

enhance network security. However it's no replacement for WEP, MAC filtering or 

other protections.   

 

4.15  What is Wi-Fi Protected Access (WPA)?   

Wi-Fi’s original security mechanism, Wired Equivalent Privacy (WEP), has been 

viewed as insufficient for securing confidential business communications. A 

longer-term solution, the IEEE 802.11i standard, is under development. However, 

since the IEEE 802.11i standard is not expected to be published until the end of 

2003, several members of the WI-Fi Alliance teamed up with members of the 

IEEE 802.11i task group to develop a significant near-term enhancement to 

Wi-Fi security. Together, this team developed Wi-Fi Protected Access. 

 

To upgrade a WLAN network to support WPA, Access Points will require a WPA 

software upgrade. Clients will require a software upgrade for the network 

interface card, and possibly a software update for the operating system. For 

enterprise networks, an authentication server, typically one that supports 

RADIUS and the selected EAP authentication protocol, will be added to the 

network.   

 

4.16 What 

is 

WPA2? 

It is the second generation of WPA. WPA2 is based on the final IEEE 802.11i