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New Member
Posts: 8
Registered: ‎05-22-2017

Bandwidth cap on PtP link

Hi,

I would like some input on how to troubleshoot a PTP link (RM3) that seems to max out bandwidth at ~49Mbps no matter how good the signal strength is or how big of a channel i use (20, 25 or 40Mhz).

There is no ratelimit configured on the radios, i have double checked it with cat /tmp/system.cfg and the internal speedtest on the units max out at ~49Mbps.

Signal strength is atm -51/-52 dBm on both radios, Noise floor: -91dBm, Transmit CCQ: 96%, airmax quality: 90% and airmax capacity: 80%.

 

Kind Regards

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Re: Bandwidth cap on PtP link

Are your LAN interfaces also connected at 100M Full Duplex?

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New Member
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Re: Bandwidth cap on PtP link

Hi,

Yes they are. There are no duplex mismatches on the LAN ports.

Also, i'd like to point out that i'm measuring transmit and recieve individually when i speedtest.

 

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Re: Bandwidth cap on PtP link

Can you provide screenshots of the main dashboards and airview reports?

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Re: Bandwidth cap on PtP link

[ Edited ]

Heres the AirView from The AP:

 

image.png

 

Here's the Main page from the AP:

 

image.png

 

Here's the one from the Station:

 

image.png

 

I have tried updating to the newest firmware, that doesn't help.

I have tried different channels, that doesn't help either.

Can't send more then 50Mbps over the radios no matter what i try. I do see CPU usage at 100% when speedtesting, not sure if that's normal or not.

 

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Re: Bandwidth cap on PtP link

I would use PCs on both ends of the link to run iperf3 tests. The speedtest on the devices swallows a lot of resources trying to generate traffic.

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New Member
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Re: Bandwidth cap on PtP link

[ Edited ]

Hi,

We have tried that aswell, that only give us ~40Mbps. Both UDP and TCP.

 

From PC north of AP sending to PS South of Station:

 

[ ID] Interval           Transfer     Bandwidth       Retr  Cwnd
[  4]   0.00-1.00   sec  4.81 MBytes  40.4 Mbits/sec    8   70.7 KBytes
[  4]   1.00-2.00   sec  4.72 MBytes  39.6 Mbits/sec   20   50.9 KBytes
[  4]   2.00-3.00   sec  4.68 MBytes  39.2 Mbits/sec    0   79.2 KBytes
[  4]   3.00-4.00   sec  4.45 MBytes  37.4 Mbits/sec    8   58.0 KBytes
[  4]   4.00-5.00   sec  4.94 MBytes  41.4 Mbits/sec    0   84.8 KBytes
[  4]   5.00-6.00   sec  4.41 MBytes  37.0 Mbits/sec   22   67.9 KBytes
[  4]   6.00-7.00   sec  4.36 MBytes  36.6 Mbits/sec    4   70.7 KBytes
[  4]   7.00-8.00   sec  4.59 MBytes  38.5 Mbits/sec   16   74.9 KBytes
[  4]   8.00-9.00   sec  4.88 MBytes  40.9 Mbits/sec    1   96.2 KBytes
[  4]   9.00-10.00  sec  4.49 MBytes  37.6 Mbits/sec   13   66.5 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth       Retr
[  4]   0.00-10.00  sec  46.3 MBytes  38.9 Mbits/sec   92             sender
[  4]   0.00-10.00  sec  46.1 MBytes  38.7 Mbits/sec                  receiver

iperf Done.
New Member
Posts: 8
Registered: ‎05-22-2017

Re: Bandwidth cap on PtP link

Surely this should not be normal, something needs to be wrong with either radio.

Is it possible to send any files to UBNT for review?

 

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Re: Bandwidth cap on PtP link

I would double check both devices for Traffic Shaping in the Network tab Advanced Config mode.

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Re: Bandwidth cap on PtP link

@UBNT-JoshMcGee both unit operates in Basic mode (that way there is no way trafficshaping is active right?)

 

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Re: Bandwidth cap on PtP link

Some settings in advanced mode are retained when switching back to simple mode.

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Re: Bandwidth cap on PtP link

[ Edited ]

@UBNT-JoshMcGee

 

I switched over to Advanced mode and Trafficshaping is disabled on both radios.

Still can't push more then 50Mbps either way.

 

advnetw.jpg

 

What more can i try before RMA?

 

Kind Regards

 

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Re: Bandwidth cap on PtP link

I would try using parallel connections in the iperf3 test. It's clear that we're seeing a bottleneck, but it is not yet clear where that's at.

Try adding something like `-P 5 -t 100` to the iperf commandline, and running a couple tests in reverse as well with the `-R` flag to verify that neither PC is struggling to generate the necessary amount of traffic.

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Re: Bandwidth cap on PtP link

Hi,

I decided to put a AF3X up above the troubled link to see an airview when the link was operational.

This is what i see from the AF3X (no active link, just powered to see Airview:

av-r3.jpg

 

I have configured the R3 link on 20Mhz and 3600 centered. as per this picture:

 

r3.jpg

 

I'm no expert in reading airviews but why is it so wide? And why is it red (more intense) on the left side and yellow/green on the right side? Chain issues?

I would expect a red waterfall between 3590 and 3610 with some yeallow/green 5Mhz on either sides, or is that just imagination?

 

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Re: Bandwidth cap on PtP link

I wouldn't put too much stock into the airView graph. It looks a little unusual but it's also essentially an accurate result according to your description of the link/spectrum.

Still hoping you could refer to my previous post and verify the iperf tests. Once we have that ruled out, I'll have to look at the support files from the units.

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