lte_connectivity: Unexpected PDN event: 6

RE: lte_connectivity: Unexpected PDN event: 6

helsing — Thu, 21 Dec 2023 15:12:42 GMT

Hi Jordan, sorry for the delay. You could check out nrf\samples\cellular\at_monitor.

RE: lte_connectivity: Unexpected PDN event: 6

Kyle — Fri, 15 Dec 2023 18:13:09 GMT

Thanks Helsing. In the link you provided though, it doesn't mention URC or "unsolicited". Would you be able to provide a code example of how to register a handler to catch this error?

RE: lte_connectivity: Unexpected PDN event: 6

helsing — Fri, 15 Dec 2023 15:04:08 GMT

Hi Jordan,

There is a missing case in lte_net_if that causes this.

You may in any case register your own URC(Unsolicited Result Code) so that you get a notification from the modem.

https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/libraries/modem/at_monitor.html

Thank you, Achim, for your contribution.

RE: lte_connectivity: Unexpected PDN event: 6

Achim Kraus — Fri, 15 Dec 2023 07:47:07 GMT

just a community answer

RE: lte_connectivity: Unexpected PDN event: 6

Kyle — Thu, 14 Dec 2023 19:21:25 GMT

Thank you. For clarity (since I'm not clear on your role), are you providing an official answer on behalf of Nordic, or just a community answer?

RE: lte_connectivity: Unexpected PDN event: 6

Achim Kraus — Thu, 14 Dec 2023 07:22:08 GMT

> Any idea

Some information has been given later in the referenced ticket,

"the APN rate control feature is controlled by the network and not the device itself.
It is the network that toggles this feature to control how much data the device is allowed to send."

And there is some GSMA spec 4.7.7 Support of rate control of user data using CIoT EPS Optimisation

In my case it is only triggered during FOTA, not for normal operation. FOTA is only required pretty rare, so It should not harm to restart the modem once during such a download. If in your case normal-operation already triggers the rate-limit, I guess you need to contact the SIM card provider.

> Any thoughts

My app doesn't use the events directly, it rather checks the rate limit with at cmds and tries to restart the modem restart the modem by switching lte_lc_power_off() and lte_lc_normal() .

I used that at-cmds, because the event wasn't fired with the NCS version I was using when I stumbled over it.

How to do that best in your/Nordic's app is unfortunately out of my scope.

RE: lte_connectivity: Unexpected PDN event: 6

Kyle — Wed, 13 Dec 2023 20:38:50 GMT

> I guess, there is a switch, which doesn't handle these two new pdn_events.

Any thoughts on where I could find some sample code that shows how to handle these pdn events? I need to be able to detect it to restart the modem.

Also, are there API functions that correspond to restarting the modem (would that be conn_mgr_all_if_down followed by conn_mgr_all_if_up)?

Regarding PDN rate control, looking at the nRF PDN page, it shows the config options but I can't find any details that explain what PDN rate control is actually doing, why it's necessary (or when to use it), or what the rate limit actually is. Any idea where I could find more info on this?

And finally, to disable this rate control, I would have thought it would just be a `CONFIG_PDN_EVENT_APN_RATE_CONTROL_OFF=y` in the prj.conf file, but it's throwing an error saying "unknown symbol". How do I actually disable rate control?

RE: lte_connectivity: Unexpected PDN event: 6

Achim Kraus — Wed, 13 Dec 2023 08:44:02 GMT

You're using NCS 2.5.0?

"PDN event: 6"

That is one of the new pdn_event types for rate-limit-management, PDN_EVENT_APN_RATE_CONTROL_ON and PDN_EVENT_APN_RATE_CONTROL_OFF.

See +CGEV: APNRATECTRL STAT - Not reported with pdn_event_handler_t

I guess, there is a switch, which doesn't handle these two new pdn_events.

> so the sample doesn't detect the error to reset the connection. ... so it requires a hard reset to fix the issue.

"reset the connection" will not be enough, but restarting the modem (off/on) with NCS 2.5.0 will do the job without "hard reset".

See AT%APNRATECTRL for more details.

In my case the limit was 256 messages in 24h. Well enough for usual traffic using CoAP/DTLS 1.2 CID, but blocking FOTA.