[Xastir] UDP frames

[Alan Crosswell]

I'm sorry but I'm a committed Internet Protocol bigot.  I would never use a MAC 
layer feature that is unique to only a given Mac implementation.
/a

jeff at aerodata.net wrote:
> 802.11b mac layer is not ax.25. In fact, lots of nice little bells and
> whistles we should take advantage of.
> 
> Default mode of 802.11b clients is to do a active scan of the channels,
> seeking a specific SSID (or in the case of 'all', any ssid). So channel is
> almost irrevelent in the case of AP's (BSS).
> 
> Consider WRT54G's for your AP's. Not the best, but certainly one of the
> most flexiable (run open source linux) and very cheap (street price
> $55-65).
> 
> Since we are doing low bandwidth applications such as APRS, "store and
> forward" will not make large demands on the throughput. The WRT54's (and
> many other) AP's support WDS (Wireless Distribution System) mode, which is
> a crude form of mesh networking. So, you'd have one connected AP, and then
> sprinkle WDS enabled AP's along your proposed route. And remember, the WDS
> enabled AP only needs power.
> 
> 
> 
> 
>>Thing of coordinating frequency and SSID in adhoc mode just like
>>coordinating
>>frequency and PL...  Sure there's gotta be coordination.
>>/a
>>
>>J. Lance Cotton wrote:
>>
>>>Alan Crosswell wrote:
>>>
>>>
>>>>Bill Vodall wrote:
>>>>
>>>>
>>>>>Hmmm.   Taking this a bit further.  Won't an 802.11x device have to be
>>>>>in ESS (peer-to-peer mode) instead of IBSS (controlled by an Access
>>>>>Point)
>>>>>before it can pick up raw UDP packets?    This shouldn't be hard to
>>>>>test..
>>>>
>>>>
>>>>Nope.  UDP is just UDP.  What the infrastructure (or lack thereof)
>>>>does is irrelevant.  Think of it as working simplex (ESS) vs. working
>>>>via a repeater/digipeater (IBSS) is all.
>>>
>>>
>>>Except that if your 802.11b card is blasting away UDP packets in ad-hoc
>>>mode with the 'ssid' set to "abcd" and my 802.11b card is sitting next
>>>to it in ad-hoc mode with the 'ssid' set to "wxyz", my card doesn't hear
>>>anything from yours. So there has to be some amount of coordination.
>>>It's obviously not the same as AP association, but it's similar. Kismet,
>>>the 802.11 sniffer requires that your wireless card driver allows the
>>>card to be put in 'rfmon' mode, which is like promiscuous mode for wired
>>>ethernet. There has to be some kind of 'association' using the ssid or
>>>you have the equivalent of an ethernet card with no cable plugged in.
>>>
>>>Now, if we could get a wedge program that would turn on rfmon mode in
>>>the wireless driver, then we could have a 1-to-1 equivalent with
>>>AX.25/APRS...
>>>
>>>-Lance
>>>
>>>
>>>>You use UDP all the time when you watch streaming video or other
>>>>applications like that which can tolerate some packet loss and keep
>>>>working.  You drop some video packets, the picture just gets a little
>>>>jumpy but it keeps working.
>>>>
>>>>/a
>>>>
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>>>
>>>
>>>
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> 
> 
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