ExtremeCloud IQ Radio Profiles

 Within ExtremeCloud IQ (XIQ), you can edit tons of advanced radio features. In this post, I'll go over some of the main "nerd knobs" that you can edit.

Let's start with the some of the most important tuning, transmit powers and channel selection:

By default, your 5GHz radio will have a generic configuration, this included a txPower range of 5-20dBm. I have seen APs from many vendors prefer to stay towards the upper end of their power range. Due to this, it is best not to leave this at default, especially if you're in a dense deployment. I've seen many schools have one AP per classroom, in this situation, it can be detrimental to keep the max at 20dBm. Tune this down to your needs and if at all possible, conduct a site survey to validate what txPower you should be using.

Next, your transmission power floor set to 5dBm by default, again, the AP may prefer to stay on the upper end of the max, but still tune this to where you see fit.

Max power drop will determine how far you would like the radio to adjust at any one time. You may decide 9dB is too aggressive and turn this down, but that will depend on your environment and how drastic you want your power changes to be.

Max clients indicates the max allowed associations for this radio, 100 is set by default, but you can get aggressive and tune this down lower as a form of forcing a set number of clients per radio per AP.

Next is denying 802.11b clients, you can do this at the radio level through this setting or enforce the same by making 12mbps a mandatory rate in your SSID configuration. I'll go over advanced SSID configuration in another post. You do NOT want 802.11b clients on your network for a number of reasons, those clients should be less of a problem today, but take precautions.

Channels:

By default, most vendors I've seen do this, 20MHz and no DFS channels. This is what would be considered a 'safe in all environments' kind of selection because there's no telling where an AP will just be thrown up and configured with an SSID without the administrator tuning the radio profile. So by default you get a not great configuration. It is by no means optimized.

So what should you configure this to be? It depends.

If you do not have a problem with frequent DFS events, absolutely use DFS channels. If you are not terribly dense and/or have high attenuation value materials separating where your APs are deployed (thinking K-12s with concrete walls) you may get away with 40, or even in some rare cases 80MHz channel widths. This all depends on your deployment, the biggest thing to keep in mind is your density. If this is a huge lecture hall with 500 seats (at 100% expected wireless adoption rate) and 10 APs, 80MHz is not for you as there are too few channels, causing too much interference. 

Other advanced settings:

Some clients do not respond well to band steering. Basically, the AP will ignore probe requests from clients for the 2.4GHz band to encourage the client to connect to the 5GHz radio. The problem being the client driver (what a bad client driver? NEVER) preferring 2.4GHz and roaming/connecting very slowly because of this. With a good design, you can implicitly encourage 5GHz connectivity anyway by limiting the number of 2.4GHz cells and managing their transmit power and data rates. By default this is switched to off but is on in this image to show the configuration.

Here are the default settings for this portion. Notice that many of the WiFi 6 features are off by default. The most important feature I see here is OFDMA as that is the 'secret sauce' of WiFi 6. Many clients do not support MU-MIMO and due to a few key factors MU-MIMO does not get a lot of use and is considered by many to be a feature that is marketed a lot but not used.

From here you can also enable Transmit Beamforming, a technology meant to improve SNR but has overhead due to the sounding process required, read more on this here https://extreme-networks.my.site.com/ExtrArticleDetail?an=000099149

Guard interval is the spacing between symbols, I would not touch this setting in most environments.

Aggregate MAC Protocol Data Units allows for multiple frames to be combined on transmission. Every 802.11ac frame is an A-MPDU and many chipsets in .11n also support A-MPDU. Basically with this enabled you do not have to send one frame at a time, drastically increasing speeds. I do not see any reason to turn this off unless you want to cripple your wireless.

There are more settings in here that are vendor specific, but I wanted to cover the agnostic settings here to help guide your optimization. Many items you can change in these advanced settings can drastically change the operation of the radio and in turn the client experience. Please be cautions of just enabling/disabling settings without researching the full impact it can have on your clients.

References:

CWNA-108 Study Guide by David Coleman and David Westcott