The a/g card will have a radio that can switch between 2.4 and 5.2 GHz. Unless I am mistaken, the way the card comes up is that it scans 2.4+ and then 5.2+ ranges to find APs to authenticate with. When authentication is done, then the card is set to that frequency. This is most likely done in hardware and is not accessable from firmware.
Therefore, you would need 2 radios in your station card and I am unaware of any station card that has 2 radios. So, you are stuck using 1 channel. If you were to do this on 1 channel then you will be creating interference for the AP and its clients. Your collision rate would skyrocket and your system would fail. Besides the fact that this is technically not allowable under the standard 802.11. If you had a directional antenna and rewrote the firmware to avoid all the collisions you would be generating, then perhaps. You would also need to use multiple MAC addrs. The hardware again will probably get in your way. It is designed to work within 802.11 and packets that are not 'proper' are generally dropped. To receive packets from both 'networks' you would need to respond very quickly ~30ns. Though atheros does have a concept of a MAC mask that would allow you to receive on 2 MAC addrs, the code I believe is in the AP side and not the station side and would not work on 2 channels anyway.
So, you would need to talk on 2 separate channels and in order to do this, you will need 2 radios with custom drivers to do the routing. Given the slim margins on these things, I doubt any station card has 2 radios. There is no need for this as the station generally only talks to a single AP at a time.
I hope this is accurate and helps,.
Barry
To: Gilles Boccon-Gibod <[EMAIL PROTECTED]>
Cc: [EMAIL PROTECTED]
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
It is not possible to setup your configuration with one card. Once it is associated to an AP, the client is already in an infra structure mode and can not do adhoc.
Technically, it is possible to do this with one card which is a 'a'/'g'
combo card but I doubt if any driver supports this mode.
-Dominic
Gilles Boccon-Gibod wrote:
> Is there any wya to run an 802.11 card in two modes at the same time
> in order to create a single radio repeater/router? More precisely, I'd
> like to configure a card+driver so that it acts as a STA (client
> connected to an access point), and also send/receive packets on an
> ad-hoc network. Then, I want to route packets to/from the ad-hoc
> network and the access point network.
>
> What I'm trying to do is the following:
> a laptop L1, with an 802.11 PC card, connects to an Access point AP1,
> which is connected to the internet. L1 also joins an ad-hoc network,
> on the same channel as AP1, also joined by a second laptop L2. L2 can
> talk to L1 over the ad-hoc network, but cannot talk to AP1. When the
> second laptop wants to send packets out to the internet, it would
> route through the laptop L1 by sending packets on the ad-hoc network,
> which L1 would then send out through AP1:
>
> L2 <--- ah-hoc ---> L1 <---- managed/AP mode ----> AP1 <--- internet
>
> Now, this is very simple to do if L1 has TWO PC cards. One joins the
> ad-hoc network, and the other one connects to the AP. But I want to do
> it with a single PC card. Of course, this will most likely force me to
> have the ad-hoc network be on the same channel as the AP, but that's Ok.
>
> Essentially, this is a one-radio repeater.
>
> Any idea how to do this (on Linux, BSD, or any other system) ?
>
> -- Gilles
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