Thread MAC errors

[krbvroc1]

I have setup a small thread network (1 FTD Router, 1 Border Router, 2 MTD Dongles) using the Nordic provided RaspPi border router image.

I have been attempting to get Thread based OTA DFU updates. I am finding a 450KB image is taking from 12 - 35 minutes.

Running wireshark on the RaspPi, I notice a fairly frequent retranmission even though wireshark sees the response. Each time this happens the IoT CoAP stack pauses 5 seconds.

As you can see from the snippet below - the RaspPi did reply with the ACK. Yet it would appear the DFU target did not process that ACK.

While trying to troubleshoot this, I have noticed on the nrf52 devices, using the 'counters mac' CLI command that RxTotal -> RxErrFcs increases quite a bit.

Example: During the DFU - RxUnicast: 6864 / RxErrFcs: 283 which is about 4% FCS rate.

I also notice on the RaspPi border router the command 'wpanctl get Thread:NeighborTable:ErrorRates' shows a high FrameErrRate - many times between 10-30%.

I am not sure what to look at next to determine what is going on.

[krbvroc1]

Just to add some more info... I used the Thread packet sniffer and when I see these 5 second delays, this is what it look likes at the 802.15.4 level.