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Date:      Wed, 2 Mar 2005 01:26:45 -0500
From:      Bob Johnson <bob89@bobj.org>
To:        freebsd-questions@freebsd.org
Cc:        Christopher Kelley <bsd@kelleycows.com>
Subject:   Re: Does 802.11b use a lot of resources?
Message-ID:  <200503020126.46489.bob89@bobj.org>
In-Reply-To: <421EB26B.5050608@kelleycows.com>
References:  <421EB26B.5050608@kelleycows.com>

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On Friday 25 February 2005 12:06 am, Christopher Kelley wrote:
> Have I tried too hard to squeeze usability out of an old computer?
>
> I have a Pentium-166 that has been a faithful router & firewall (FreeBSD
> 5.3 and pf) for a couple years now.  It has no trouble with the 3 to 4
> Mbps I get from my broadband connection, at least not with ethernet.
>
> I wanted wireless, so I could use my laptop around the house.  I
> dutifully read the section in the manual about setting up FreeBSD as an
> access point. I'm using a Netgear MA311 802.11b card (Prism 2.5
> chipset).  And it does work, except it's very slow.  Now I know that I
> can only expect about 50% of the rated speed with wireless, but I
> figured even if I got only 4Mbps, I'd be fine.  But I get less than
> 1Mbps.  I've updated the firmware, added a signal booster and hi-gain
> antenna, and I have "excellent" signal strength throughout my house.
>
> So my question is, is there more overhead with wireless than with
> ethernet?  TOP doesn't seem to show that I'm taxing it too hard, idle
> never goes below about 70% with polling enabled (Hz=1000), and never
> below about 80% with polling disabled.  Am I expecting too much out of
> an old Pentium-166?
>

My experience is that:

1) 50% throughput is probably the best you should expect.  I generally plan on 
3-4 Mbps for an 11 Mbps 802.11b card.

2) Using 128-bit encryption (WEP) will significantly slow down some (many?) 
cards. The WEP processing is done on the card (I think), and they simply 
don't have hefty processors. If you use 128-bit WEP, try 64-bit WEP and see 
if that speeds things up.  64 bit WEP is adequate to keep out casual 
snoopers, and 128 bit is not adequate to keep out a serious attacker, so the 
difference in security may not be as important as some believe.  64-bit WEP 
is also known as 40-bit, and similarly for 128-bit WEP.

3) Turning on power management seriously slows things down for me, to well 
below 1 Mbps. Do a "wicontrol" and make sure Power Mgmt is "0".

- Bob



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