Encryption affecting performance?

Hi,
I'm working on a project on large wireless network and I have one
question. What are transfer rates when using 802.11g with WPA or WPA2
encryption and EAP-TLS authentification? Is there any affect of using
encryption on wireless network's performance?

--
alex

On Fri, 12 Aug 2005 10:33:33 +0200, Alex81 <(E-Mail Removed)> wrote:

> I'm working on a project on large wireless network and I have one
>question. What are transfer rates when using 802.11g with WPA or WPA2
>encryption and EAP-TLS authentification? Is there any affect of using
>encryption on wireless network's performance?

That was two questions.

This is stolen from an Atheros PDF at:
http://www.atheros.com/pt/atheros_range_whitepaper.pdf
with some additions and corrections by me.

Non-overlapping Modulation Max Max Max
Channels ------- | Link TCP UDP
| | | | |
802.11b 3 CCK 11 5.9 7.1
802.11g (with
802.11b) 3 OFDM/CCK 54 14.4 19.5
802.11g only 3 OFDM 54 24.4 30.5
802.11g turbo 1 OFDM 108 42.9 54.8
802.11a 13 OFDM 54 24.4 30.5
802.11a turbo 6 OFDM 108 42.9 54.8

The paper claims that encryption is enabled for these calculations,
but my numbers seem to indicate that these number are for encryption
disabled. Dunno for sure. The Max TCP and Max UDP are the
theoretical maximum thruput rates.

It's difficult to estimate the effects of encryption on thruput. Rule
of thumb is about 15% loss as compared to un-encrypted. The payload
for WEP and WPA with RC4 encryption are identical. Only the key
exchange uses a different algorithm, but the same number of packets.

WPA2 comes in various flavours and implimentations. AES encryption is
usually done in hardware, but here are software implimentations. The
all software implimentations tend to be somewhat slower but not much.

The method of authentication has absolutly no effect on thruput as it
only happens perhaps once every hour or so.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831.336.2558 voice http://www.LearnByDestroying.com
# http://802.11junk.com
# (E-Mail Removed)
# (E-Mail Removed) AE6KS

Jeff Liebermann wrote...
[cut]

Thanks, that was very helpful :-)

--
alex