Re: [Madwifi-devel] mw as access point

[Benoit P. <ben...@fr...>]

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hom...@ib... a écrit :
| Hello,
|
| I have installed a MadWifi based AP, to perform some contention
| measurements. I have connected 6 clients, all madwifi based, and splitted
| the 6 in 3 pairs of two. Each of the two sends 192 packets of UDP
| generated traffic of 1376 bytes each(approx 2 Mbits per second). This
| means the channel should be used at about 25 Mbits. Taking into
| consideration the channels capacity is 27 Mbits for 802.11g for raw data,
| at 54 Mbits transfer rate, I wanted to achieve a stressed channel. Instead
| I observed that the pairs register lost packets. I investigated the queues
| of the MadWifi Access Point. Both the transmission queue and the receiving
| queue are not stressed, but remain under 10 packets. Also the queues at
| the clients are not stressed.

How do you check the queues? There are lots of queues. Some queues are
software queues where the hardware will pick up packets.

|
| There is loss and rate adaptation also takes place. I have to mention the
| environment is interference free (controlled environment) with very good
| signal quality. RTS CTS is disabled and the stations are positioned in a
| circle at a radius of approx. 4 meters of the AP.
|
| I suspect I can't see anything in the queue because, the MW doesn't
| enqueue the packets to be forwarded for example from sta1 to sta2 and vice
| versa. Maybe it is even done at hardware level.

Forwarding is done at software level, in the madwifi driver.

|
| Can anybody from MadWifi confirm this? Is my bottleneck and source of
| losses the AP and if so, is there a hw forwarding the reason I see no
| stress in the queues?

Maybe the AP is the contention point? What rate control are you using?
Could you have another node in monitor mode to see what's going on in
the air?

|
| Regards,
| Silviu Homoceanu.

Regards,
Benoit

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