Forum

Hi all.

I've a question about fragmentation of encrypted MPDU.

On the Wiley's book about CWAP I read:

"Notice that the unencrypted MPDU, which includes the MAC header, frame body, and CRC, must not exceed the fragmentation threshold. Fragmentation does not take into account frame body expansion due to encryption; thus encrypted fragments may exceed the fragmentation threshold size."

I've a doubt about it: The book said that encrytion overhead is not considered during the fragmentation process, right?

Therefore, for exemple, with a 300 bytes fragmentation limit, the end result of encrypted frame fragmentation will be more than this value?

Thanks a lot.

Americo

That could be interpreted as: "The fragmentation decision is done before encryption. ...thus the encrypted fragments may exceed the fragmentation threshold."

Disclaimer: No, I haven't checked the standard nor have I looked at actual packets to confirm. I trust/hope the author has done his homework. This is just how I would read such a paragraph.