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Date: Sat, 18 Mar 2006 08:06:39 -0800
From: Sam Leffler <sam@errno.com>
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To: Kan Cai <kcai@cs.ubc.ca>
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Cc: freebsd-net@freebsd.org
Subject: Re: Wireless sensing function is missing?
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Kan Cai wrote:
> 
> 
> On Sat, 18 Mar 2006, Bruce M Simpson wrote:
> 
>> On Fri, Mar 17, 2006 at 02:00:28PM -0800, Kan Cai wrote:
>>>   I wonder if this is true that sensing function is missing? If yes, 
>>> is it
>>> supposed to be implemented in the driver or net80211 layer? Thanks in
>>> advance!
>>
>> It's a function of the 802.11 hardware. I assume you're describing the
>> CSMA/CA technique. The Coordination Function (CF) in use will also have
>> an effect but you don't specify if you're in IBSS or EBSS mode.
> 
> Yes, I meant CSMA. But I was actually using ralink card, which has 
> 802.11 firmware implemented in open source. I am aware that freebsd has 
> a 80211 layer as well. So before I dig into the source, I would 
> appreciate it if anyone can let me know where CSMA is implemented, in 
> the driver or net80211 provided by freebsd.
> 
> I tried both ad hoc mode and hostap mode, btw.

DCF is implemented in hardware.  Carrier sense is part of that.

	Sam