Virtual WiFi on Linux?

Dan Searle dan at
Thu Oct 20 08:20:50 EDT 2005


Sorry if I'm using the wrong terms here, please correct me....

Thursday, October 20, 2005, 1:06:16 PM, you wrote:

>> Then, run 16 separate MAC layers with some kind of modification to the
>> HAL to share (schedule) the PHY layer between the 16 MAC layers.

> No, you 'multiplex' 16 instances of the "upper MAC" over a single  
> instance of the "lower MAC".

But if you just use simple multiplexing, would you not end up with
contention between the different upper MAC instances? I'm thinking a
more intelligent scheduling scheme would be needed to ensure the 16
upper MAC stacks share the lower MAC in a "fair" manner?

I.e. if we are the lower MAC and have basically 16 incoming queues of
transmit traffic from the 16 upper MACs, how do we decide which frames
to transmit first? Do we simply round robin the 16 queue's or would
some kind of intelligent scheduling achieve better throughput/sharing
of the lower MAC and ultimately the PHY??

>> Received frames are not under our control, so all the scheduler would
>> have to do is share out the PHY transmit buffer (e.g. SFQ?).

> Huh?

Sorry, was just trying to point out that we would only have to
multiplex/schedule the transmit buffers as the radio can't control
what frames arrive on the PHY, and hence in what order/priority the
upper MAC layers get on the receive side of things.

>> I think this would require either modifying any existing lower MAC
>> (HAL), or perhaps writing a completely new lower MAC (HAL).

> The HAL (in madwifi anyway) is not the "lower MAC".

Sorry, I'm getting my HAL and lower MAC boundries confused here.

Regards, Dan...

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