Ping Instability on Serial LTE Modem

RE: Ping Instability on Serial LTE Modem

Øyvind — Fri, 08 Nov 2024 14:36:03 GMT

Hello, our developers inform me that you should not select prj.conf as this is picked up by the build system automatically, and by selecting this through -DCONF_FILE="prj.conf" it messes with the build configuration.

More information can be found here: https://docs.nordicsemi.com/bundle/ncs-latest/page/zephyr/build/kconfig/setting.html#the_initial_configuration

RE: Ping Instability on Serial LTE Modem

Oguzhan Turk — Fri, 08 Nov 2024 10:56:04 GMT

I detected the problem. Sorry, It was not related with 2.6 or 2.7 SDK.

Here was the working solution's build command on the output tab of VS code:

west build --build-dir build . --pristine --board nrf9160dk/nrf9160/ns -- -DNCS_TOOLCHAIN_VERSION=NONE -DEXTRA_CONF_FILE=overlay-ppp.conf -DEXTRA_DTC_OVERLAY_FILE=overlay-ppp-without-cmux.overlay -DBOARD_ROOT=.

And here was the not working solutions's:

west build --build-dir build . --pristine --board nrf9160dk/nrf9160/ns -- -DNCS_TOOLCHAIN_VERSION=NONE -DCONF_FILE=prj.conf -DEXTRA_CONF_FILE=overlay-ppp.conf -DEXTRA_DTC_OVERLAY_FILE=overlay-ppp-without-cmux.overlay -DBOARD_ROOT=.

AS you can see the difference is:

-DCONF_FILE="prj.conf"

Btw: I modified the paths on commands ("build", ".", "prj.conf" etc.) above with relative path. Normally, VS Code was generating them with exact path with my folder names.

If I select "prj.conf" for "Base configuration files (Kconfig fragments)" it was not working (unstable ping), otherwise works fine. On the other firmware application "modem shell" it was not a problem with selecting but it is for slm. So, question is why?

RE: Ping Instability on Serial LTE Modem

Oguzhan Turk — Fri, 08 Nov 2024 08:31:54 GMT

I'm in Germany and using O2 sim card. It was LTE-M connection. I didn't change anything but modified the overlay file for ppp connection.

I also tried Serial LTE Modem of 2.6 SDK with 1.3.6 firmware and same modified ppp overlay file and then it worked perfectly:

ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8): 56 data bytes
64 bytes from 8.8.8.8: seq=0 ttl=113 time=165.667 ms
64 bytes from 8.8.8.8: seq=1 ttl=113 time=191.232 ms
64 bytes from 8.8.8.8: seq=2 ttl=113 time=165.185 ms
64 bytes from 8.8.8.8: seq=3 ttl=113 time=128.151 ms
64 bytes from 8.8.8.8: seq=4 ttl=113 time=159.620 ms
64 bytes from 8.8.8.8: seq=5 ttl=113 time=119.200 ms
64 bytes from 8.8.8.8: seq=6 ttl=113 time=163.098 ms
64 bytes from 8.8.8.8: seq=7 ttl=113 time=204.357 ms
64 bytes from 8.8.8.8: seq=8 ttl=113 time=181.489 ms
64 bytes from 8.8.8.8: seq=9 ttl=113 time=197.444 ms
64 bytes from 8.8.8.8: seq=10 ttl=113 time=178.525 ms
64 bytes from 8.8.8.8: seq=11 ttl=113 time=190.697 ms
64 bytes from 8.8.8.8: seq=12 ttl=113 time=150.017 ms
64 bytes from 8.8.8.8: seq=13 ttl=113 time=189.505 ms
64 bytes from 8.8.8.8: seq=14 ttl=113 time=163.905 ms
64 bytes from 8.8.8.8: seq=15 ttl=113 time=188.434 ms
64 bytes from 8.8.8.8: seq=16 ttl=113 time=148.029 ms
64 bytes from 8.8.8.8: seq=17 ttl=113 time=184.078 ms
64 bytes from 8.8.8.8: seq=18 ttl=113 time=143.896 ms
64 bytes from 8.8.8.8: seq=19 ttl=113 time=184.349 ms
64 bytes from 8.8.8.8: seq=20 ttl=113 time=152.094 ms
64 bytes from 8.8.8.8: seq=21 ttl=113 time=195.506 ms
64 bytes from 8.8.8.8: seq=22 ttl=113 time=154.951 ms
64 bytes from 8.8.8.8: seq=23 ttl=113 time=194.785 ms
64 bytes from 8.8.8.8: seq=24 ttl=113 time=149.357 ms
64 bytes from 8.8.8.8: seq=25 ttl=113 time=192.802 ms
64 bytes from 8.8.8.8: seq=26 ttl=113 time=152.842 ms
64 bytes from 8.8.8.8: seq=27 ttl=113 time=192.650 ms
64 bytes from 8.8.8.8: seq=28 ttl=113 time=152.106 ms
64 bytes from 8.8.8.8: seq=29 ttl=113 time=190.597 ms
64 bytes from 8.8.8.8: seq=30 ttl=113 time=134.619 ms
64 bytes from 8.8.8.8: seq=31 ttl=113 time=175.662 ms
64 bytes from 8.8.8.8: seq=32 ttl=113 time=135.141 ms
64 bytes from 8.8.8.8: seq=33 ttl=113 time=171.926 ms
64 bytes from 8.8.8.8: seq=34 ttl=113 time=132.017 ms
64 bytes from 8.8.8.8: seq=35 ttl=113 time=222.372 ms
^C
--- 8.8.8.8 ping statistics ---
36 packets transmitted, 36 packets received, 0% packet loss
round-trip min/avg/max = 119.200/169.341/222.372 ms

So, I think, something was broken for Serial LTE Modem on transition from 2.6 SDK to 2.7 SDK.

RE: Ping Instability on Serial LTE Modem

Øyvind — Thu, 07 Nov 2024 08:29:16 GMT

Hello again,

The developers agree that this is suspicious, but with limited information on how they can reproduce it is difficult to tell exactly what causes thiis.

Are you able to provide more information on the setup of each application. E.g. are both using LTE-M? How do you configure each sample before starting this test? Do you have more logs to share from each from startup? Are you able to collect modem traces as well during each test? What SIM card are you using?

Thanks!

Kind regards,
Øyvind

RE: Ping Instability on Serial LTE Modem

Øyvind — Thu, 07 Nov 2024 07:51:21 GMT

Hello,

I've forwarded your question internally to those who develop the SLM.

Will get back to you by end of the day.

Kind regards,
Øyvind