host_decrypt

Jiří Farták jfartak at wms.cz
Sat May 3 13:02:50 EDT 2003


Hello friends,

there's on thing that rather confuses me - rate throughput according the
hostap_decrypt parameter setting. I'm using three Z-COM Xi-626 (Prism 2.5,
STA firmware 1.5.6) cards on my AP: two are runnning in ap mode, the third
is in managed mode with enabled WEP (on all cards). They are embedded in the
old Intel Pentium MMX 233MHz, 64MB RAM, Kernel 2.4.20, WExt 25, hostap
0-0-1.

When I turn host_decrypt on (prism2_param's host_decrypt value set to 1,
thus the decryption is done by the driver , i.e. host CPU), throughput
increases up to nearly 100% percent. That is confusing - this computer is
old, and even if I heard about some performance loss when using PRISM based
cards with WEP enabled, I wouldn't expect so dramatic increase. The same
thing happened (the increase was not so markable, however) on much powerful
Linux boxes. I thought that when decryption is done by the card itself then
it doesn't depend (roughly) on how the box (CPU) powerful is. It appears to
me as the meaning of the parameter would be reversed - 0 means host
decryption, 1 card based decryption.

Any comments, ideas?

Thank you

Jiri Fartak




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