On Fri, Nov 09, 2007 at 11:52:30AM +0100, Johannes Berg wrote: > Something I'm not clear on right now is the timing of it all. If there > are say two BSSes, the driver can simply program the hardware to half > the beacon period and then the beacons will alternate. But if there are > seven BSSes, the beacon period might not be divisible by seven so timing > errors will happen and, worse yet, accumulate. Does hostapd somehow > account for this? Or should the beaconing work completely differently, > for example with all N beacons sent in a burst? You could always modify the beacon period to a suitable number that would be divisible by whatever number of BSSes there are and/or add empty slot to move from, say, 7 to 8, and just not send a beacon at some of the slots. Sending a burst of all beacons at the same time is also a valid option up to a certain limit on how long a time would be allocated for this. However, this may have some timing issues when there are multiple power save buffered broadcast/multicast frames waiting to be sent out. In general, it would be good to try to send the beacon frames as close to their correct time as possible to allow power saving stations to remain asleep most of the time. Some low-level operation would also need to make sure the beacon timestamp is correct if the frame gets delayed due to other frames. I think it would be perfectly fine to try to simply the configuration and implementation by requiring all BSSes to use the same beacon interval and allow small changes in the interval, if needed. hostapd does not have code for this type of modifications. I've done some experiments with configuring the hardware to use beacon interval divided by number of BSSes, but ended up using burst of beacon frames instead (and all BSSes were forced to use the same beacon interval). -- 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
