Does 802.11b use a lot of resources?

[Christopher Kelley]

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.
>
>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
>
>
>  
>
Well, 3-4 Mbps would be fine, as that's about what my broadband runs at 
anyways.  At the risk of being pedantic, when you say 3-4 Mbps, do you 
mean including overhead or not?  In other words, if you use say the 
bandwidth tester extension for firefox, would you expect to see 3-4 
Mbps, or rather somewhat less than that due to overhead?  I realize it 
may seem a stupid question, I just want to make sure I'm comparing 
apples to apples.

Just for testing, I turned off WEP completely, and verified that power 
management was off.  No change.  Drat. 

Now I am wondering if it's very firmware sensitive.  I'm using Primary 
1.1.1 and Station 1.8.0 - I guess I could "downgrade" the firmware to 
either 1.3.4 or 1.4.9 - I had figured that more recent would be better, 
but now I'm wondering.  The man page is 2 years old, though, so I don't 
know what versions were actually available when it was written.

Thanks for your help, I really do appreciate it, even if it doesn't 
actually "solve" my problem.

Christopher.