Supporting data rates below mandatory

[eglinsky2012]

I was recently advised to set 24Mbps as the minimum mandatory data rate and 18Mbps as supported. I'm wondering if having one supported data rate below the minimum mandatory data rate is considered best practice. I had been under the impression that this was bad, but they stated that this can help with roaming. The 24Mbps mandatory was selected in the context of a sports arena (very high-density). I did a search on this forum and saw something similar suggested a few years ago.

Is this still considered a best practice? Also, what about mandatory rates in a less-dense AP scenario, where 5 GHz may be around -65 for RSSI? Would a 24Mbps mandatory be acceptable in that instance, or would a 12Mbps mandatory be more stable? I'm referring to a variety of devices, such as laptops (PC and Mac), phones, etc.

[Haydn Andrews]

Few things to consider

Client support at the minimum mandatory data rate

generally I dont change data rate from minimum of 12MBPS unless very high density and the RF has been designed and tested to meet higher minimum rates

I wouldnt do it as a whole either, as i would seperate the RF profiles based on the areas being served as well, ie high density areas get higher and lower density have 12MBPS.

Remember if the client can not meet the 24MBPS it will drop

[eglinsky2012]

@Haydn AndrewsThanks for the info. I guess I'm not sure where the line lies between "high density areas" and "lower density areas". Would you consider a classroom that seats 30 with a single AP a "high density area" with 24Mbps minimum or "lower density" with 12Mbps minimum? Or is there an RSSI range in which 24Mbps is usable, and as long as coverage is within that range, 24Mbps would be acceptable? Etc.

[JPavonM]

I'm not a friend of using non-standard basic data rates, I mean, other than 6-, 12- or 24-Mbps. These rates are the only ones mentioned in the IEEE 802.11 standard as basic, and it could happen that a vendor implement them as starndard in the driver/firmware, so using a different one will prevent connecting those devices.

I suffered this with some IoT stuff (smart power switches), so try to follow the standard.

[eglinsky2012]

@JPavonM- I'm confused about the practical implications of your statement. Do you mean you disable anything above, below, and in between 6, 12, and 24Mbps? Or do you mean you wouldn't use anything besides those for the lowest mandatory rate? Either way, I'm curious what your thoughts are on having a supported rate below the minimum mandatory rate (whichever that is).

[JPavonM]

I mean to only select 6-, 12- and 24-Mbps as basic rates if IoT stuff or non-enterprise assets connect to the WLAN infrastructure, or if you do select another one as 18-Mbps, test all current and future assets.

Mandatory rates allow devices to connect, and they cannot connect if the rate that they can connect is not a basic one (becuase of the distance). By supporting rates below the mandatory ones you are allowing devices to connect at a given rate, and then move away from the AP with lower rates.