On Thu, Dec 18, 2008 at 07:02:55AM +0530, Sujith wrote: > But after receiving a CSA on the current frequency, and having moved to the new > advertised frequency, can the STA send out probe requests in the earlier frequency ? > (In case of a scan run or something) As far as IEEE 802.11 standard is concerned, yes, that would be allowed. There are not even explicit limits on doing that (if it is a broadcast probe request, not unicast to the current BSS) before the channel move. The only thing that the STA has to do immediately (if mode=1) is to cease to send anything to the current BSS before the channel switch. When receiving the CSA, the STA needs to decide whether it wants to follow the AP or not. If not, it could start scanning immediately for another AP.. The standard even has a following statement about channel switch: "It should also be stressed that the channel switch process is distinct from the regulatory requirement to cease transmission on a particular channel in the presence of radar." However, the STA must discontinue operation on the channel if it detects a radar operating in the channel or learns this from another STA. The regulatory rules on how quickly this must be done (and how much airtime may be used after the radar has been detected) may be quire strict, so doing an active scan on the previous channel immediately after having received a CSA may not be that good of an idea. Then again, channels that require radar detection should not really allow active scanning on them in the first place. In that way it would be enough for the non-AP STA to just stop using the current BSS because any other AP on the same channel should stop Beaconing, too, when a radar is detected and as such, the non-AP STA should not end up using the channel anymore. -- Jouni Malinen PGP id EFC895FA -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
