Re: Offtopic? Windows 7 Virtual Wifi adapter.

[Stuart Ward <stuart ward bcs org>]

Isn't this just mesh networking without the auto configuration bits.

-- Stuart Ward M +44 7782325143



2009/5/18 Dan Williams <dcbw redhat com>:
> On Mon, 2009-05-18 at 11:44 -0400, Darren Albers wrote:
>> On Mon, May 18, 2009 at 11:00 AM, John W. Linville
>> <linville tuxdriver com> wrote:
>> > On Mon, May 18, 2009 at 10:57:05AM -0400, Tom Sutherland wrote:
>> >> Ran across this article today:
>> >>
>> >> http://www.engadget.com/2009/05/18/microsofts-virtual-wifi-will-make-windows-7-wireless-adapters-d/
>> >>
>> >>
>> >> >From the article...
>> >> "The tech lets one piece of WiFi hardware be represented in Windows as
>> >> two separate adapters, meaning you can connect to two hotspots
>> >> simultaneously if you like, or turn your virtual device into an access
>> >> point that others can connect to."
>> >>
>> >> In the long term, would something like that be relevant to
>> >> networkmanager?
>> >
>> > You have to make it work in the kernel first...
>> >
>> > John
>> > --
>> > John W. Linville                Someday the world will need a hero, and you
>> > linville tuxdriver com                  might be all we have.  Be ready.
>>
>> Don't some wireless drivers support this already with multiple
>> subinterfaces that correspond to a VLAN?
>
> They dont' really correspond to a VLAN, they appear as separate
> "wiphy" (aka wireless phy) devices which can be configured separately.
>
> Note that by doing this "splitting", you're effectively time-sharing the
> adapter, and your transfer rate will go down by more than half, since
> the adapter has to be on one channel for 1/2 the time, and the other
> channel for the other 1/2 the time.  It's actually more than 50% because
> there's channel switch time involved, and probably null-packet exchanges
> when jumping to a channel to notify the AP that you're coming back from
> sleep.
>
> Yes, it can work, and yes, some mac80211 drivers support this type of
> functionality, but something that *also* should be done is figuring out
> how to tell users that little Elves didn't magically replace the single
> radio in their wifi card with two separate radios, and about the
> inherent limitations thereof.
>
> You could of course do a STA + AP with the same card on the same
> channel, where for instance the STA was connected to an existing AP, and
> you were connection-sharing the traffic out over the your own
> just-created AP to friends or something.  But of course there you'll
> also be increasing contention of the medium (since you're effectively
> broadcasting the same traffic on the same channel twice, once from
> friend -> you, then you -> real AP).  There is no silver bullet here of
> course, unless you really do have two wifi cards in your machine.
>
> Dan
>
>
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