When do to more Control Slots than suggested?

I know the manual says that you set it to 2 when you have 51 to 150 on that AP.
Is there any reason you should ever go to 3 when you still fall in the 51 to 150 range?

I just don’t understand how you can actually look at the stats to determine where you should be, or do you just strictly go by what the manual says?

Look at the RF CB Stat. A high discards to octets count indicates too few control slots.

In or out on those values Jerry?

either.

Take the total out and div/ discards. I would say anything over 5% indicates a potential problem.

Just the answer I’m looking for, thanks again Jerry.

BTW That may not be the only indicator. YMMV

We have found in high noise environs, more control slots can help.

And in those situations the test you gave above came back normal?

What are your values on your worst performing AP?

I just did a check on mine, they are less than 1% so 5% might be high.

Mine was about 2% so it wasn’t bad, I have 82 SMs though on that 900 Mhz AP, i’m guess it’s just too much bandwidth being pushed through.

Is it going to hurt things if you set the slots higher than it needs to be?

Let’s say it was set to 5 for some reason…

Adding control slots is a trade in overall throughput as less time is available for transmitting actual data. We run as few as necessary without sacrificing performance.

I was told my our moto guy we cant have more than about 45 max subs on an AP and maintain throughput. So is there a performance degredation even with increased slots with alot of SMs/AP?

thatoneguysteve wrote:
I was told my our moto guy we cant have more than about 45 max subs on an AP and maintain throughput. So is there a performance degredation even with increased slots with alot of SMs/AP?

We have well over 50 subs on a couple of AP's with plenty of headroom left, so it really boils down the bandwidth pkgs. you offer, QOS config, and the amount of bandwidth avail. to the AP/SM.

I believe the idea behind control slots is to accommodate SMs during high load periods. Control slots increase the available air time so that more SMs can transmit/receive. The trade off is you lose overall aggregate throughput because there is less time in each slot to transmit/receive, therefore less possible throughput in each slot.

Depending on how you have your bandwidth profiles set up and your oversubscription rate, you can get more than 50 subs on an AP. When we first started with Canopy, we didn’t see performance issues on our 900MHz APs until around 60 users. Most of our users were subscribed to a 512k package.

We use 3 control slots and 15 miles range for 5400 APs, with about 30-60 customers each.
When they are under maximum load, they reach the full troughput (about 5200kbs DL).
I noticed that with few control slots it’s more difficult for an SM to register in case of heavy traffic on the AP, is it possible?

Ciao
Massimo

Network registration will use air time so I certainly would see a case for it being true.

Yes, Control slots are specifically allocated time slots for registration, timing and downlink information, when an SM can transmit, etc.

If an AP is very busy, all of the registered SMs are using the control slots and there is no room for a new SM. Adding another control slot provides that bit of extra time for an SM to communicate with the AP.