Sat Mar 26, 2022 1:01 am
2 years later ... some more experience
- AFAIK WMM is disabled in the default config. It can be enabled in the wireless config for each WLAN interface. Some client device (iphone) seem to want to see WMM enabled. CAPsMAN always turns on WMM (CAPsMAN limitation) for WLAN managed by CAPsMAN.
- WMM does not do anything by default. It is about using different timings to get an opportunity to transmit. (Airtime contention process). Video and voice use smaller numbers for the contention window waits, and as such get priority for transmission. The various WMM timings are distributed in every AP beacon, and they are the 802.11 standard values.
- But to be effective the packets must be marked as video or voice in their priority, and MT does not do this without specific priority IP firewall mangle rules or bridge filters.
- MT is very conservative in using AMPDU aggregation for all prioriities except for priority zero (the default priority). So when setting WMM and setiing priority in mangle rules or bridge filters, don't forget to consider using AMPDU in the HT tab for other priorities. Again CAPsMAN may not allow to set this.
Identifying traffic and giving it video or voice priority is the implementors responsibility. Mikrotik does not make that decision, and does not even use the DSCP-high-bits for that priority by default.
(Priority setting does not leave a router or AP, DSCP travels with the data packet)
(non-WMM traffic and the default "Best effort" WMM traffic (priority=0) use the same timing values.)