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super_mario25 asked on

802.11 frame size

Hi all,

I am a bit confused about the 802.11 frame size and how it changes when applying WEP and WPA.

Unencrypted 802.11 frame:
header    |   data          | FCS
(30)           (0-2312)        (4)  bytes

WEP frame:
header    | IV   |  EIV    |  data          | FCS
(30)           (4)     (4)      (0-2312)        (4)  bytes

WPA (TKIP) frame:
header    | IV   |  EIV    |  data          | MIC     |   ICV    |   FCS
(30)           (4)     (4)      (0-2312)        (8)           (4)       (4)  bytes

My questions is: Is the data of each of the above frames correct or does it decrease? If it doesnt decrease, than the total frame sizes will be 2346, 2354 and 2364 respectively. Is this correct? I am really confused because all literature says that the packet size of body (data) is 0-2312 but the largest frame size is 2346 (RTS Threshold default).

Any help will be appreciated, Thank you in advance,
Wireless NetworkingEncryptionWireless Hardware

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8/22/2022 - Mon

2304 (2312 is actually the maximum WEP encrypted payload) is your maximum payload - note payload, not frame - size before encryption.  Max encrypted frame - note: not payload- sizes are 2346, 2354 and 2364 as you have listed above.

Check this link for more information you may find useful:  http://www.cwnp.com/phpBB2/viewtopic.php?t=836&


can you please clarify this:
2304 (2312 is actually the maximum WEP encrypted payload) is your maximum payload

thank you again

2304b is the actual maximum, unencrypted payload size.
2312 is the maximum payload after encryption.

These are both the maximum payload un/encrypted.  The maximum frame sizes are 2346, 2354, 2364 w/encryption.
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William Peck

Thank you again for the reply atlas,
Just to clarify everything, the payload you are refering to is the data part I have indicated on the diagram above, right?
So, agreeing with the maximum frame sizes, the payload of 2304 (unencrypted) and 2312 (encrypted) exists for No enryption, WEP and WPA frames or does it increase?

Thank you again.

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