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Old 01-14-05, 08:34 AM   #5 (permalink)
Howard2k
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The very basic concenpt behind pre-amble is that when a frame is passing from one machine to another it can be hard for a particular machine to see where a frame starts. There would typically be a steady stream of data over the network so the idea was to use a pattern that would signify "start of frame coming up". The stations see the pattern and know when to expect the start of the frame.

It also plays a part of collision avoidance/detection.

Whether WEP was enabled or not, pre-amble would still be relevant. Ironically the pre-amble actually doesn't change regardless of of WEP/WPA or any other encryption.

The difference between long and short pre-amble is that as part of the original specifications for 802.11 (there was as standard called 802.11 which preceeded 802.11b/a/g/n etc) a long string (pre-amble) was used. To increase performance, in 802.11b they allowed the option of a short preamble. Less "bits" wasted travelling over the network.

There are probably some devices that cannot use short pre-amble, but there can't be many.

The best approach is to set them all to short or set them all to long.

The challenge is that you cannot always do that. My 4150 for example has a registry key to enable me to change it, but through the GUI I have no capability.


Menthol> You should check the documentation with the router and ensure that the wireless is actually turned on. If you're not seeing it but it DOES have an SSID then maybe it's not active.
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