Does 802.11b use a lot of resources?

[Loren M. Lang]

On Wed, Mar 02, 2005 at 01:26:45AM -0500, Bob Johnson wrote:
> 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.

Actually, what I recommend for home you, if you have the time, is IPSEC.
Much more secure than WEP and it's all done on the main cpu so it should
slow the wifi down as much.  There's a good article on freebsddiary.org
I believe.

> 
> 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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