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Why large speed difference between TKIP and AES encryption?

Last response: in Wireless Networking
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March 19, 2011 7:01:34 PM

I was playing around with my wireless router settings and I noticed something strange.

When I set my computer to use AES encryption, my link connection speed became greater than 54 Mbps. Unfortunately, running some internet speed tests showed a consistent download speed of less than 400 kbps, although my upload stayed around normal at 4000 kbps.

When I switched to TKIP encryption, my link connection slowed down to 54 Mbps (which I'm assuming means it switched to G mode rather than N). However, my speed tests resumed their normal fast speed of downloading at 10,000 kbps or higher, and upload around the same 4000 kbps range.

I'm trying to figure out why the heck this would happen? Is this a problem with my wireless card? A problem with my wireless router? Has anybody seen anything like this before?

Thanks.
March 20, 2011 12:04:31 PM

i have never seen.. normally would recommend aes because it is a much more secure. Whenever you enable security on a wireless network you take some kind of performance hit (security requires extra bandwidth and processing time). Maybe your router did not ship with aes and it was part of a firmware upgrade and aes is to much math for the router??

when you did speed test was it to the same site? and you did it a few times?
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March 21, 2011 6:25:07 PM

Yep. Exact same test site and performed test twice for each encryption within a matter of minutes. Did 2 aes, switched encryption, then 2 tkip, then one final round of 2 aes.

I think I read somewhere that aes uses the router hardware for encryption/decryption... so I may try another router. I may also try two laptops at the same time and see what happens.
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March 28, 2011 12:08:27 AM

I've now tested it on 2 laptops to confirm it is not a problem with my wireless card. Whether it is a problem with my router or not I have no idea but I am suspecting the answer is yes.
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February 1, 2012 2:38:20 AM

I have experienced the exact same issue with a Zoom 5350 wireless-N cable modem/router using multiple wireless test systems. Using TKIP forces all wireless connections to 54Mbps or less on my router.
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July 13, 2012 10:48:49 AM

The group that sets the WIFI standards are phasing out TKIP and WEP. They have well known security problems. New routers with 'n' (2010 or later) will only work with TKIP or WEP encryption in 'g' mode.
They didn't kill TKIP and WEP for 'b' and 'g' mode in order to guarantee that older equipment would still be forward compatible.
If you are using mixed mode 'n' + 'g' for example, these routers drop you to 'g' if you use anything other than AES encryption. Some routers warn you, but sadly few.
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November 14, 2012 3:26:56 AM

I just want to add that sometimes you need to use TKIP specifically if you have a new router and a very old laptop/computer with wireless G. thats the only way i got mine working.
It was communicating with the WAP and getting a valid IP but no internet connectivity
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November 14, 2012 11:17:49 AM

The encriprion slows down the connection speed. The router simply needs more time to encrypt the data it is transmitting.
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November 15, 2012 4:09:54 AM

ngrego said:
The encriprion slows down the connection speed. The router simply needs more time to encrypt the data it is transmitting.




Agreed but why would it waste time encrypting incoming data without affecting upload speeds? Does that not imply it isn't bothering to encrypt the OP's outgoing data which, to my mind, is far more important.


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November 15, 2012 10:08:09 AM

This a very old thread but it isn't that tkip is any slower...actually aes is since it takes more processor to encode.

The reason it works this way is part of the n standard. If you tell it to run tkip it will not run faster than the g standard. If you run AES then you can go to whatever the max speed N allows.
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