Hello Stefan, On Sun, Oct 31, 2021 at 9:25 PM Stefan Sperling <s...@stsp.name> wrote: > Some access points advertise BSS load information in beacons in > order to help clients make informed roaming decisions. > > BSS load information includes the number of associated stations, > the channel utilization (this takes other networks on the same > channel into account), and current admission capacity (interesting > for clients which use QoS, which we do not). > > We currently ignore BSS load information and only use RSSI to tell APs > apart. With this patch we store bss load information for APs during > scans if available, and take it into account when chosing an access point. > > Unfortunately, I do not have a suitable AP available to test with. > tcpdump can be used to check whether an access point supports this > feature. Run this command while associated to the access point: > tcpdump -n -i iwm0 -y IEEE802_11_RADIO -s 4096 -v > > If the AP reports BSS load information you should see something like > this among the information printed by tcpdump: > 64 stations, 100% utilization, admission capacity 0us/s > > It would help to get this patch tested in an environment where access > points advertise BSS load information, with a roaming test between > different access points. > I wrote down information about how roaming can be tested here: > https://marc.info/?l=openbsd-tech&m=163329420019842&w=2
This topic was discussed a couple of weeks ago on the hostapd mailing list (http://lists.infradead.org/pipermail/hostap/2021-October/039961.html). And Jouni Malinen provide a few concerns about switching to the QBSS load IE usage. I would like to quote him: > I would also point out that at least the last time I did some testing > between vendor implementations, the reported values were completely > different between two APs on the same channel in more or less the same > location in the test setup.. In other words, I would not place much, if > any, trust in this value being something that could be compared between > two different APs. The only thing that seemed to be more or less > comparable was the values from the same AP device in a sense that the > channel load value increased when there was more traffic on the > channel.. So I do not think that the complete switching to the BSS load metric is a good idea. But utilizing the AP assistance in the BSS selection procedure sounds nice. -- Sergey
