Re: [Madwifi-devel] Max throughput? Bonding? WDS? Turbo?

[Darrell B. <bu...@on...>]

Humm, user list questions on the dev list (IMHO)... Well, I suppose I 
can save the devs some time:

On Mar 24, 2004, at 9:52 AM, Daniel Prather wrote:

> Just a few quick questions.  All more or less unrelated I guess.
>
> What's the max throughput anyone has gotten with madwifi?  So far my
> experience has been 21-22mbps on 802.11a using some card with the
> Atheros a/b/g chipsets.  Has anyone gotten faster?  These are only 
> about
> 10 feet apart too, with external antennas, and nothing but air between
> them.

You're doing well then. See http://www.atheros.com/pt/papers.htm for 
some theoretical numbers. You can push 40 if it's all UDP data, 24 or 
so with TCP.

> Has anyone been able to bond two or more cards together to achieve
> higher throughput?  I've tried it with ifenslave and bonding in the
> kernel, but it thinks they're ethernet cards (which I guess makes sense
> because bonding is usually for ethernet) and tries to set the cards to
> full duplex and 100mbps.  Needless to say, this doesn't work.

Havn't ever tried this, but if the kernel bonding always assumes it's 
an ethernet card, you might be stuck. You could try building a 
multi-link ppp tunnel over different cards, or just enabling mutli-path 
routing in the kernel and ensure you have a route over both cards. 
Another trick would be to use one link for inbound and one link for 
outbound, taking advantage of the half-duplex nature of the wireless 
link might net you higher overall throughput if your traffic is 
relatively balanced.

> Next, is WDS present in any of the madwifi builds currently?  I know
> that it was talked about before, someone had written stuff for it was
> not incorporated into the official repository.  Is there anything other
> than WDS that can be done to make two access points talk to one
> another?  Or does anyone know if WDS will happen very soon?

No WDS right now, apparently planned but low on the list.

> Lastly, is it possible to get Turbo mode in 802.11a to work on 
> user-defined
> channels?  It seems to only work on somewhere around 5.2 or 5.3GHz and 
> refuses
> to let you set the channel to anything else.  I'd like to see if I 
> could make
> it operate in the 5.725 to 5.825 GHz range.

Turbo mode restricts the available channels because of the way it way 
it works. I suppose some of the devs may contradict me, but unless 
someone goofed up in the channel selection code, it's a FCC/operating 
mode restriction.

   -Darrell