[BC660K-GL] How does a NB IoT device know the state of PDP context on the network side?

[brixton]

Hello friends,

I have been trying to simulate a real-world situation by running the following test:

I have a BC660K-GL NB IoT device. It has an active PDP context/“bearer” and is connected to a PDN. It’s able to send data via QISEND and that data is received on a server.

At some point, I delete the PDP context/“bearer” through a button on the dashboard of the network provider.

How can the NB IoT device determine that the PDP context/“bearer” on the network side is now deactivated/deleted? What AT commands would be able to give information about this? The commands CGACT, CGDCONT, CGATT, QISTATE, CGPADDR are of no use. They only say something about the PDP context/“bearer” on the side of the device, not the network.

AT+QIACT is also of no use, since it is not available for BC660K-GL.

Firmware BC660KGLAAR01A05_01.001.01.001

See logs and network provider dashboard overview below.

[2023-07-20_14:13:34:202]ATi
[2023-07-20_14:13:34:202]Quectel_Ltd
[2023-07-20_14:13:34:202]Quectel_BC660K-GL
[2023-07-20_14:13:34:202]Revision: BC660KGLAAR01A05

[2023-07-20_14:13:34:202]OK
[2023-07-20_14:13:38:803]AT+CGPADDR?
[2023-07-20_14:13:38:803]+CGPADDR: 0,"XX.XXX.XXX.XXX"

[2023-07-20_14:13:38:803]OK
[2023-07-20_14:13:44:237]AT+CGDCONT?
[2023-07-20_14:13:44:237]+CGDCONT: 0,"IP","IOT.1NCE.NET","XX.XXX.XXX.XXX"

[2023-07-20_14:13:44:237]OK
[2023-07-20_14:13:45:243]AT+CGACT?
[2023-07-20_14:13:45:243]+CGACT: 0,1

[2023-07-20_14:13:45:243]OK
[2023-07-20_14:13:55:235]AT+QIOPEN=0,0,"UDP","XX.XXX.XXX.XXX",YYYY,YYYY
[2023-07-20_14:13:55:235]OK

[2023-07-20_14:13:55:235]+QIOPEN: 0,0
[2023-07-20_14:15:35:721]AT+QISEND=0,5,"5bf03b1d55"
[2023-07-20_14:15:35:721]OK

[2023-07-20_14:15:35:721]SEND OK    <------ after the  SEND OK,  the PDP context is deleted from the network side (by the user). 
[2023-07-20_14:16:39:467]AT+QISTATE?
[2023-07-20_14:16:39:467]+QISTATE: 0,"UDP","XX.XXX.XXX.XXX",YYYY,YYYY,2,0,1

[2023-07-20_14:16:39:467]OK
[2023-07-20_14:16:44:540]AT+CGACT?
[2023-07-20_14:16:44:540]+CGACT: 0,1

[2023-07-20_14:16:44:540]OK
[2023-07-20_14:16:46:772]AT+CGDCONT?
[2023-07-20_14:16:46:772]+CGDCONT: 0,"IP","IOT.1NCE.NET","XX.XXX.XXX.XXX"

[2023-07-20_14:16:46:772]OK
[2023-07-20_14:16:49:374]AT+CGPADDR?
[2023-07-20_14:16:49:374]+CGPADDR: 0,"XX.XXX.XXX.XXX"

[2023-07-20_14:16:49:374]OK

[2023-07-20_14:19:43:887]AT+QISTATE?
[2023-07-20_14:19:43:887]+QISTATE: 0,"UDP","XX.XXX.XXX.XXX",YYYY,YYYY,2,0,1

[2023-07-20_14:19:43:887]OK
[2023-07-20_14:56:06:351]AT+QISEND=0,5,"5bf03b1d55"
[2023-07-20_14:56:06:351]OK

[2023-07-20_14:56:06:351]SEND OK
[2023-07-20_14:56:15:725]
[2023-07-20_14:56:15:725]+IP: XX.XXX.XXX.XXX   <--- New IP address is shown, which indicates that there has been a change in PDP contexts. 

[brixton]

Any ideas on this, @herbert.pan-Q ? Many thanks

[herbert.pan-Q]

Quectel_EPAT操作指导与参考(CN&EN)_BC260Y&BC660K&BC28F&BC95GF&BC300Y.pdf (2.1 MB)
Can you provide the corresponding debug log?

[brixton]

yes, is there an email adres I can send it to? I don’t want to send logs with IP logs etc on a public forum.

[herbert.pan-Q]

herbert.pan@quectel.com

[brixton]

Great, I’ve sent the logs.

[herbert.pan-Q]

I don’t think your operation is working

[brixton]

Which operation isn’t working? The PDP context deletion? Or the executing of PDP related AT commands?
And what does that then mean?

And on my PC I don’t see what you’re seeing in the log files. Index 5266 doesn’t show up in SigLogger for some strange reason, and nothing shows up in ASN1/NAS box either… do you know why that is? I have everything checked on the message filter…
Many thanks

[herbert.pan-Q]

You need to import the comdb file in the firmware file for parsing

[brixton]

okay thanks I found the file you meant. I also downloaded wireShark now to be able to view the ASN pane.

So back to what you pointed out about the SERVICE_REJECT, what does “implicitly detached” mean? Is that an opposite to an “explicit” detach? If so, what is the difference?

[herbert.pan-Q]

[brixton]

okay thanks for that. Which document is this that you’re referencing? Something publicly accessibel?

[herbert.pan-Q]

3gpp24301-h20.pdf (8.6 MB)