PTP Link Disassociating: ePMP 2.4 GHz TDD NLOS

I have an ePMP PTP link that is disassociating quite often. 

Details:

  • 2.5 Firmware
  • 2.4 GHz
  • 5  MHz channel
  • TDD PTP
  • -72 dBm signal 
  • NLOS

I set the syslog to collect everything. This is the most common combination of events on the SM for disassociating:

Sep  5 06:10:54 ePMPsm kernel: mlme_sta_swgpfmiss_high_caa_timer_handler: GPFs miss, probably, because of high CCA threshold level. Restore default CCA level.
Sep  5 06:19:11 ePMPsm kernel: SM disassociated from AP[00:04:56:c9:6c:1c] F=2432 11nght05. Reason: 48 (COMMUNICATION LOST)
Sep  5 06:19:11 ePMPsm kernel: br-lan: port 2(ath0) entering disabled state

When running, it runs very well, then it disassociates for several seconds. It appears to always "Restore default CCA level" and then lose communication.

Any thoughts? I'm going to test another channel, and possibly try downgrading to 2.4.3.

Thanks, Chris

Hello,

The error is a generic link disconnect that could be cause by interference in the channel. Trying a cleaner channel, if available, or configuring the system to use MCS0 for Management messages (see the Configuration->Radio page, under Scheduler) might help in this situation.

Regards

We had a PTP link do this in 5Ghz. also.  The question I would ask would be, is the SM side of the PTP link set to 'Auto' power?  If so, you may want to set the power to manual and turn the power up.  The signal being -72, you may have done this already, or it may be attempting it's highest power now, if it's a distance shot, but if not, it might be worth trying.  Our theory was the radio was acheiving just enough power to stay linked up, but the slighest noise or signal flucation was dropping the link off.  After we switched to manual power and turned the power up, we have not lost the link since.

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@Luis wrote:

The error is a generic link disconnect that could be cause by interference in the channel. Trying a cleaner channel, if available, or configuring the system to use MCS0 for Management messages (see the Configuration->Radio page, under Scheduler) might help in this situation.


The channel did have sporadic noise on it. I switched to another channel and the issue has only happened in several days. I will monitor it closely and consider MCS0 for management messages. 

Thank you for the explanation.


@Ben Royer wrote:

We had a PTP link do this in 5Ghz. also.  The question I would ask would be, is the SM side of the PTP link set to 'Auto' power?  ... Our theory was the radio was acheiving just enough power to stay linked up, but the slighest noise or signal flucation was dropping the link off.  After we switched to manual power and turned the power up, we have not lost the link since.


I do have the power manually set as high as the FCC allows; this link is only a couple miles, but with some heavy foliage. My confusion came from modulations that would normally be MCS14 and then just drop off completely and re-connect. As stated above, it turned out the sporadic noise was strong enough to kill the link. A clean channel cleared up the issue almost completely. 

Did you try setting the auto power threshold to a higher value, or did that not help maintain the links?

[A note: The ePMP radios have been doing a good job of handling the foliage and foliage movement with wind.]

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