UE cannot finish PDU establishment request (COTS UE + SRSRAN)

[gckopper]

The issue

"Select SMF failed: DNN[internet] is not supported or not subscribed in the slice"
I'm using srsran configured with a plmn id 00101 while UE uses 90170 (with roaming enabled).
I'm using a Samsung A33 5G as the UE.
The srsran and UE work with other cores (open5Gs and OAI-CN) so I don't think that's the issue.

Versions

srsRAN Project 23.10.1
free5gc-compose v3.3.0

UE status when issue occurs

[
  {
    "AccessType": "3GPP_ACCESS",
    "CmState": "CONNECTED",
    "Guti": "00101cafe0000000009",
    "Mcc": "001",
    "Mnc": "01",
    "PduSessions": null,
    "Supi": "imsi-901700000028080",
    "Tac": "000001"
  }
]

Logs

dnn-issue.tar.gz

[abousselmi]

Hi @gckopper

I can see this in the AMF logs:

2024-02-05T18:27:12.881400195Z�[36m [INFO][AMF][Gmm][amf_ue_ngap_id:RU:1,AU:2(3GPP)][supi:SUPI:imsi-901700000028080] �[0mSelect SMF [snssai: {Sst:1 Sd:010203}, dnn: internet]
2024-02-05T18:27:12.892019380Z�[31m [ERRO][AMF][Gmm][amf_ue_ngap_id:RU:1,AU:2(3GPP)][supi:SUPI:imsi-901700000028080] �[0mSelect SMF failed: DNN[internet] is not supported or not subscribed in the slice[Snssai: {Sst:1 Sd:010203}]

but nothing in the SMF logs. Do you have other logs from the SMF ?

[gckopper]

First of all, thank you for the response!

Yes, those are all the logs the SMF is producing.

I was also able to figure out this issue, I had to add the phone's plmn to the plmnList of the SMF (in the config/smfcfg.yaml file)!

@@ -28,6 +28,8 @@ configuration:
   plmnList: # the list of PLMN IDs that this SMF belongs to (optional, remove this key when unnecessary)
     - mcc: 001 # Mobile Country Code (3 digits string, digit: 0~9)
       mnc: 01 # Mobile Network Code (2 or 3 digits string, digit: 0~9)
+    - mcc: 901
+      mnc: 70
   locality: area1 # Name of the location where a set of AMF, SMF, PCF and UPFs are located
   pfcp: # the IP address of N4 interface on this SMF (PFCP)
     # addr config is deprecated in smf config v1.0.3, please use the following config

However, there is a new issue.

[ERRO][AMF][Ngap][amf_ue_ngap_id:RU:3,AU:4(3GPP)][ran_addr:191.4.204.112:42476] Build InitialContextSetupRequest failed : SEQUENCE OF Size is lower than lowerbound

I've attached the pcaps generated by srsRAN once again and now all the core functions have their log level set to trace.
Looking at the wireshark dissection, the 5GSM cause for the rejection was a Network Failure (38).

lowerbound.tar.gz

[gckopper]

TL;DR

There is a workaround to this issues I was having and I was able to connect the COTS UE to the internet using srsRAN with a USRP. The configuration used is in the attached file.

What's the issue?

The issue seems to be the usage of roaming. The sim card I was using had a PLMN of 90170 and the cellphone (Samsung Galaxy A33 5G) used seems to block connections to this PLMN. Due to my inability to change the PLMN of sim card I was using roaming with a network configured for the test PLMN (00101). However, after changing the phone used to a Oneplus Nord 5G and changing the network to use the same PLMN as the sim card, it worked!

Takeaways

• Samsung seems to block some PLMNs like the 90170 even though it has an international MMC
  • Our Samsung Galaxy A33 5G and my Samsung Galaxy A53 5G demonstrated this behavior.
• Oneplus doesn't seem to block the 901 MMC, at least in the Nord 5G model we tested.

Files

These files contain the logs for all core functions, pcaps and configuration files used. The logs for srsRAN were not included because of their size of over 16MB compressed.
free5gc-srsran.tar.gz