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Member
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8.3.0 PtMP AC very low capacities

[ Edited ]

I installed 8.3.0 on an existing Rocket 5AC Prism AP with 7 AC clients.  Without doing anything else, download speeds went up from about 45 to about 60 megabit.  However, switching to pure AC mode dropped capacities to about 20% of what they were in mixed mode.  Speed tests from the AP to the client radios supported this precipitous drop in capacity.

 

I didn't fiddle with it much, since the AP is in use, but I tried 5ms and 8ms fixed frame with 50/50 and 67/33 duty cycles, all with the same results.

 

Is there some good documentation I can read up on to figure out what I'm doing wrong?  Thanks.  (-:

 

P.S.: So far I'm very happy with the new firmware!

 

Edit: I didn't accurately describe what was happening.  AC PtMP Mixed mode and AC PtMP mode with flexible frame length were both performing about the same, and both were much higher than with version 8.0.2.  Setting a fixed frame length with or without asymmetrical duty resulted in dramatic (about 80%) reduction in capacity.

USA, the Land of the FCC
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Re: 8.3.0 PtMP AC very low capacities

The GPS Sync Design Guide has some good basic information, but I'm not sure we understand all the variables you are working with based on your description above.

 

We have been told that Mixed Mode currently uses the latest and best flexible frame code, whlie Pure AC mode currently lags a bit.

 

Fixed frame mode will deliver less download compared with a lightly loaded flexible frame AP, but latency will be much more predictable, especially as the load increases.

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Re: 8.3.0 PtMP AC very low capacities


 

We have been told that Mixed Mode currently uses the latest and best flexible frame code, whlie Pure AC mode currently lags a bit.

 


 

Is this still valid with 8.3.0 ?

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Re: 8.3.0 PtMP AC very low capacities

Is it really mixed mode that does it? Isn't it PtP vs PtMP, AC PtP is better then AC PtMP?

At least in my own basic test I get this result if I remembered right and AC PtMP vs mixed mode PtMP is not so much difference.

 

I also read somewhere that it might be a interference problem and that PtMP is better at handling it then PtP. Don't know if that is true and that PtP might still be better is a really quiet environment?

 

@UBNT-James This kind of stuff seems so "well known" on this forum (for a small group of people) but for new ubnt users it is very hard to find information. It would be nice to have a sticky thread for new users with all known quirks, stuff comfirmed/under fixing process (no need to report) and other gotchas/good to know.

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Re: 8.3.0 PtMP AC very low capacities

@UBNT-James Some YouTube videos might be nice too, even just some public help sessions that others may benefit from.

USA, the Land of the FCC
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Re: 8.3.0 PtMP AC very low capacities

@benvanderjagt

 

When you say " switching to pure AC mode" you mean you first tried Flexible option, and then went on to try the 50/50 and 67/33 option and saw the same results ?

 

 

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Re: 8.3.0 PtMP AC very low capacities

Oops, I didn't properly describe what I was seeing.

 

AC PtMP mode with Flexible frame duration appears to work pretty much exactly as well as AC PtMP Mixed mode.  Setting either a 5ms or 8ms frame length dramatically reduces capacity, even when I try different DL/UL ratios.

USA, the Land of the FCC
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Re: 8.3.0 PtMP AC very low capacities

We're noticing a few similar things too. We've been running the RC client for a while and had fixed frame w/ sync turned on for on AP and rolled it out to two more, with about 40 clients between the two AP's last night. This screenshot from aircontrol sums it up. Left of the capacity charter is flexible frame, rightof the chart is after turning on 5ms fixed frame at 67/33. I was pretty disappointed to see the capacity get cut by 2 to 3 times, but since this is realtively new, I don't think anyone knows the real ins and outs yet.

 

ubnt, any insight on what we should expect in this type of situation?

 

Capture.PNG

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Senior Member
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Re: 8.3.0 PtMP AC very low capacities

 

Could just be the change in capacity reporting:

  • Stated capacity in fixed frame mode is the sum of RX and TX, so the max is really the channel capacity.
  • Stated capacity in flexible frame mode is the average of RX and TX.  Since each direction can use all available bandwidth momentarily, it looks higher.
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Re: 8.3.0 PtMP AC very low capacities

I think a lot of what you are seeing is as @MimCom describes. We can make that clearer in the GUI in the next release.
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Re: 8.3.0 PtMP AC very low capacities

That seems entirely possible. We just pushed the updates last night so we haven't seen any of the real results yet, just what we tested out last night.
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Re: 8.3.0 PtMP AC very low capacities

@wispr 

 

Is it possible to provide a screen shot of the AP with this specific STA selected in the station list ?

 

Secondly, is it possible to conduct a GUI speedtest to the device ?

 

 

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Re: 8.3.0 PtMP AC very low capacities

@UBNT-SNK I didn't do any TCP tests as a client on the tower, but the built-in speed tests showed speeds in the single digits on links that were previously testing 40+.

 

I don't think I can afford to try messing with it right now, but I've got another AP that I'll be able to try it out on later.

USA, the Land of the FCC
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Re: 8.3.0 PtMP AC very low capacities

@benvanderjagt The network you tried Fixed frame was the same one as you use here ?

 

https://community.ubnt.com/t5/airMAX-AC/Tips-on-single-sector-relay/m-p/1966315#M22443

 

 

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Re: 8.3.0 PtMP AC very low capacities

No, that's just a small neighborhood Litebeam 5AC 16 that I wanted to try and tweak a little.  (-:

USA, the Land of the FCC
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Re: 8.3.0 PtMP AC very low capacities

@benvanderjagt Thanx. We will wait for your comment on the other AP when you try it. In the meantime if you want us to take a look at this AP where you reported the problem, I will be happy to. Just email me

[sriram at ubnt dot com] with the information.

 

 

 

 

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Re: 8.3.0 PtMP AC very low capacities

The other link is a Litebeam, so as far as I know I can't use fixed frame unless I replace the AP.

USA, the Land of the FCC
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Re: 8.3.0 PtMP AC very low capacities

If that is a LiteBeam AC, you can use Fixed frame. Any AC product can use Fixed frame, just that only the ones with a GPS chip can use GPS sync.

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Re: 8.3.0 PtMP AC very low capacities

If that is a LiteBeam AC, you can use Fixed frame. Any AC product can use Fixed frame, just that only the ones with a GPS chip can use GPS sync.

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Re: 8.3.0 PtMP AC very low capacities

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