Even if you don't want to change the channel per packet basis, it makes sence to use annotation instead of using syscalls. I implement a access point using click include parts of DFS (802.11h). There, the access point (ap) uses the beacon to announce a channel switch. The ap has to switch the channel after the beacon is send, where the time to switch is zero (channelswicthannouncement). So you need exact channelswitch. For the client, i use the same mechanism. Since the client has to send all packet on the new channel after receiving the beacon from the ap (time to switch=0), i use the annotation. A click-element analyse the received beacon and annotates the channel to the outgoing packets. If there is no outgoing packet in the queue, the element generates a dummy-packet with the new channel, which will be discard by the driver after setting the annotated packet, to set the channel, which is also necessary to receive packets. I think using annotations is a more accurate approach, then using syscalls.
Best regards, Robert On Montag, 27. Juli 2009, you wrote: > Javier Sánchez wrote: > > ok change the channel at ieee80211_hardstart() when the TX queues > > initialize no problem. > > > > But u can change the channel per packet basis? i think this is not > > possible, to change the channel the drivers needs to reset the chip > > and restart the tx queues. It is not like change the rate , or the > > retries.. which can be made per packet basis. > > > > But certainly i not tried or worked at it, may be i am wrong. > > This is the least of your problems, since tuning the analogue frontend > of a wireless card can take looooong time, I would expect it somewhere > in the order of of several milliseconds > > certainly something you don't want to do on a per-packet-basis.... > > but since the original question was: how to do that on reception of a > dedicated control-packet: that can make perfect sense (given that these > control packets don't happen too often...) _______________________________________________ click mailing list [email protected] https://amsterdam.lcs.mit.edu/mailman/listinfo/click
