Last Post: July 11:
I assume you mean 24 Mbps is the lowest Supported AND Mandatory rate.
If the AP is working properly then yes, the client will be disassociated (and removed from the client list in the AP).
Realize of course, in this simplified hypothetical environment, that the client won't actually "hear" the Disassociation directive ! It will continue attempting to communicate , until at some point, it too gives up trying to use that AP. It's exact behavior will depend on the clients "secret sauce".
Personally, I do not like to remove lower supported rates. I do set the lowest Mandatory rate to 18 or 24 Mbps though, when I know that there are no 802.11b devices in use. My situation was a little more complicated in the product validation lab where I was also testing /b rates.
If AP's are not placed optimally, then dropped clients and other maladies, can be expected.
One difficulty experienced in warehouses, is caused by client devices attached to fast moving forklifts. If you design for foot traffic moving at walking speeds, then you will have a problem caused by roaming delays.
Sometimes there are "tuning parameters" that can be adjusted to speed up roaming without making it more aggressive. The technique I prefer is to limit what channels the client scans on. Limiting the device to only channels one, six, and eleven reduces roaming time by over 70 %. This assumes of course that you have correctly designed your network to only use these three non-overlapping channels.
Unfortunately, not all client devices are readily configured for this. All commercial handheld printers (e.g. those from Zebra) have this ability, but a particular installer may not be in-the-know.
When you say that the client won't be able to "hear" disassociation directive you actually imply that:
- AP can actually "hear" the data from the client but will ignore it because it's received at data rate lower than 24 Mbps
- Disassociation directive is sent from AP at a data rate the client cannot properly "hear" it
- The client disassociates itself from the AP since there has been some time it didn't receive any "acknowledgement"
Is my understanding correct?
You are correct.
Remember, that in this particular case, the reason that the client cannot hear the Disassociate command is a combination of the rate and the out-of-range condition - Not just the rate.
When it comes to diagnosing problems don't forget that each manufacturer has their own "special sauce" and that, mixed with different generations of products, can cause different network behavior even with two devices that look like exact twins on the outside.
We all need to be very careful using the word "hears" when talking about Wi-Fi. If there is any ambiguity, we should always use the more precise, and probably lengthier, explanation.