We have a 5ghz cluster containing 2 PMP450i APs and 2 PMP450m APs. We have set contention slots too 1 on all APs and enabled auto contention on the 450i APs. Ever since mixing the 450m APs the frame utilization has gone up dramatically on PMP450i APs. I noticed if I disable auto contention on the PMP450i APs the frame utilization graphing clearly improves.
The PMP450i APs are due to be replaced shortly but I am sure I will encounter this at other sites.
Ideas?
hci,
If you're on 16.1.1, 16.1.1.1 or 16.2, there is a bug in the reporting of the Uplink Frame Utilization, where it reports higher than actuality. We have this fix targeted to 16.2.1.
Note that enabling Auto Contention does not change your Frame Configuration alignment. So if you adjust the number of Contention Slots on one AP, you will need to run Frame Calculator again to make sure you match with the other APs at that tower. (Or change those APs to the same Frame Configuration items: Channel Bandwidth, Downlink Data Percentage, Max Range, Contention Slots.)
Also how is your uplink throughput and latency look with Auto Contention enabled? Actually Auto Contention could even improve downlink throughput as TCP ACKs could be getting through faster. So using more of the uplink, isn't necessarily a bad thing, either. One example is the AP scheduling the SM for data when just has one small packet to send so takes up one slot. But if it takes longer for AP to schedule that SM by the time he schedules him he might have more packets to send, filling the symbol out at 8X. But the former has decreased latency but increased Frame Utilization. Just some thoughts.
Charlie
We graph frame utilization with MRTG. All I can say is when I enable auto contention on a 450i AP right next to 450m both with 1 control slot within 15 minutes I can see the upload frame utilization jump. Turn it back off on 450i and frame utilization drops back down to normal. No other changes made.
Its nice you can change this setting without rebooting. Still don't understand why simple changes like name change cause reboot and this does not.
@hci wrote:We graph frame utilization with MRTG. All I can say is when I enable auto contention on a 450i AP right next to 450m both with 1 control slot within 15 minutes I can see the upload frame utilization jump. Turn it back off on 450i and frame utilization drops back down to normal. No other changes made.
Its nice you can change this setting without rebooting. Still don't understand why simple changes like name change cause reboot and this does not.
Interesting. What version are you running?
And regarding not requiring reboot, I agree and good news is we already fixed Site Name and Location, AP Transmit Power and Sector ID, not to require reboot. Those changes are included in the next major release, targetted to be out in a few months.
16.2 but I beleive it did it on 16.1 also.