Re: use of radiotap bit 14?

Johannes Berg <[email protected]> Wed, 12 Dec 2007 18:27:56 +0100

Newsgroups	org.netbsd.radiotap
Message-ID	<[email protected]>

> Reset Namespace Field (30)
> 
>         presence bit IEEE80211_RADIOTAP_NSRESET = 30
>         1-byte alignment
>         0 bytes long
>         scope: this bit is reserved in all namespaces, and it is
>                interpreted identically in every namespace
> 
>         Upon interpreting this field, the interpreter shall reset its
>         presence-bitmap index to 0, and change to the default radiotap
>         namespace, before it interprets subsequent presence-bitmap words.

Maybe we can find somebody whose OUI we can borrow, then we could define
that the namespace selector 0 within that OUI selects the radiotap
namespace rather than having an extra bit for it. I think that would be
simpler to parse and understand.

That way, we could do everything with a single bit. Since that takes
quite a bit of space (5 bytes plus padding for each switch) the reset
bit would be useful independently to reset within a namespace. It might
make sense to define it to have a field too, namely a u8 that indicates
which offset to reset to: field value * 32 (or 24 if you accept my other
proposal)

If there is somebody willing to donate part of their radiotap namespace,
having an "experimental" selector and a selectors for each OS would
probably be useful as well.

johannes

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