ath(4) and 802.11g speed

Sam Leffler sam at
Thu Mar 9 04:09:15 UTC 2006

Daniel O'Connor wrote:
> On Thursday 09 March 2006 10:41, JoaoBR wrote:
>>> It looks like "man ath" does not list all media and mediaopt values.
>> sure not because there are lots of different cards out with different
>> mediaopts so you need to read your hw-manual or your card can answer
>> ifconfig -m ath0
> In any case I imagine there is no point forcing it to use 54Mbit - it will 
> negotiate the highest speed it can manage based on signal strength and 
> hardware support (for the AP and the card) automatically.
> I suspect forcing 54Mbit will either not work at all (because the signal isn't 
> strong enough or your hardware doesn't support it), or it will negotiate a 
> speed up to 54Mbit (which would result in no functional change).

Locking the transmit rate (and that's what setting the media does) can 
be useful but rarely when operating in any configuration but a p2p setup 
where the endpoints are fixed.  The algorithm used to select a transmit 
rate for a frame is very important to getting good performance.  John 
Bickett's sample algorithm, typically used with ath, is pretty good but 
could still be improved.


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