Rate Limit WLAN on Catalyst 9800

[thewifidude]

Is there a way to bi-directional rate limit in the QoS policy on the 9800 controller for all traffic without using Cisco ISE?

[Leo Laohoo]

There are two ways to do this:  

QoS on per-SSID (This means EVERYONE connected to this SSID will share one upload/download rate.)

QoS on per-user (Each user will have a rate limit.)

[balaji.bandi]

is this per user or per WLAN ?

check some reference :

https://mrncciew.com/2021/09/30/9800-qos-overview/

https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9800-series-wireless-controllers/215441-configure-qos-rate-limiting-on-catalyst.html

[JPavonM]

I won't recommend you using QoS per SSID/device as it is more fair to keep them transmitting and finish the communication, than disrupting it and having to restart it again. Using QoS over the wireless link breaks packet aggregation thus increasing the overhead due to the need from the same devices to send more fragmented packets.

What you get by doing this is reducing packet aggregation capabilities on the devices which is one of the features that are added in latest standrads (ac/ax/be) to inscrease the speed of the transmission.

If you finally do it, take a look on the side effects that you may introduce in the whole network, remember that wireless is a shared medium and your corporate devices also use the same for the transmission (unless you keep BYOD/Guest devices on 2.4 GHz band only), so you are potentially reducing the performance on them as well. (AP utilization, channel utilization, retransmissions, ...)