RF Out Discard/Overload issues 900AP

Gurus,

In three separate WHISP projects in 3 different geographic areas (2 rural with farmland and forests, 1 urban) I have multiple 900APs with Omnis working together, usually as remote APs pulling sync from the CMM via the BH Slave.

My Problem:
In H. township (Rural) I have fiber to a tower that has two 5700BHMs that host two remote APs. I do not have a CMM here, but provide timing at the APs via 3rd party timing modules. The two BHMs share timing (the first generates it, the second syncs via the timing port from the first). My BH links are solid, both with low jitter and predicted signal path loss. I do not think my issue is with timing or the BHM/BHS links.
I have @20 SMs registered to each AP.
I have SM users that complain of intermittent slowness in their connection, with dropped packets or very high ping times. These users span the range of link strength between the SM and the AP (-65 to -80dBm— the is a very low noise floor here) so I don’t think it is the RF link.
Both of the H. Twnshp APs have considerably higher RF Out Discards (Overloads) than either of my other WHISP’s APs.
Both APs are running 9.0 AP-DES.
To no avail I recently increased the Control Slots from 1 to 2. The remainder of the configs look like this (but are identical to my other WHISP APs except for the control slots):

Radio Configuration
Radio Frequency Carrier : 906/924
Color Code : 22/23
Sector ID : 2/3
Max Range : 10
Downlink Data : 75
Schedule Whitening : Disable
Control Slots : 2
External Filters Delay : 0 Nanoseconds
Broadcast Repeat Count : 0 (Range : 0 — 2)
Transmitter Output Power : 26 dBm ( Range: 5 — 26 dBm )

AP Bandwidth Settings
Sustained Uplink Data Rate : 20000 (kbps) (Range: 0— 40000 kbps)
Uplink Burst Allocation : 500000 (kbits) (Range: 0— 500000 kbits)
Sustained Downlink Data Rate : 20000 (kbps) (Range: 0— 40000 kbps)
Downlink Burst Allocation : 500000 (kbits) (Range: 0— 500000 kbits)
Broadcast Downlink CIR : 200 (kbps) (Range: 0— 7000 kbps)

In just one hour since I changed the control slots and rebooted the APs, They have both racked up high numbers of overloads to a relatively small amount of octets out:
RF Control Block Statistics
inoctets Count : 14318268
inucastpkts Count : 74054
Innucastpkts Count : 779
indiscards Count : 0
inerrors Count : 0
inunknownprotos Count : 0
outoctets Count : 90362462
outucastpktsCount : 94948
outnucastpkts Count : 29783
outdiscards Count : 1180
outerrors Count : 0

HELP??? Any thoughts? Why am I overloading so often? Should I cut my Sustained Data Rate? Burst allocation?

You are still well within range on outdiscards. If it is 1% or less of your total outoctets count. Most likely you are maxing out the bandwidth on the ap which in turn increases the latency due to the ap not being able keep up with bandwidth demand.

We also have some very busy AP’s. Some with 80 customers each. One site we have has 325 SM’s registered to it. After much consultation, we have found that increasing the control slots to 4 or 6 (in even number incriments, do not use odd slot numbers) Helped out. It is recomended that Broadcast repeat count should be set to 1, evidently 0 can cause packet loss, which would increase the loss you are seeing.

So here is our settings:
MAX RANGE: 20miles
DOWNLINK% 75
Control Slots 4
Broadcast Repeat 1
Schedule whitening: ON

All towers sites that are in range of each other need to be set accordingly. Hope this helps!

Good Morning, 

I am new to the world of Cambium and came across this forum response you submitted. We are experiencing users that are complaining about issues with their speed download/upload and performance in general. 

Attached you will see to photos of the AP'S in question. It seems that all contention slots are set to 5 and repeat is set to 0. 


@art72 wrote:

Good Morning, 

I am new to the world of Cambium and came across this forum response you submitted. We are experiencing users that are complaining about issues with their speed download/upload and performance in general. 


Please do not resurrect super old dead posts. Please start a new post. Also include the platform you're using (It's not clear if you're asking about PMP100 or PMP450) and the firmware revision you're using on the radios.

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