Can't establish PDU session with srsran (ERROR: [1:0] No SmContextCreateError)

[PsArzzz]

Issue Description

Hi everyone,
I am using Open5GS as the core network and srsRAN to set up the gNodeB and UE, with ZeroMQ for communication between the gNodeB and UE. However, after the UE establishes an RRC connection, it disconnects approximately ten seconds later. Upon reviewing the gNB logs, I discovered that the PDU session establishment is timing out. I seek guidance on resolving this issue to enable the UE to successfully establish and maintain a continuous PDU session with the AMF.

At first, the error in my amf.log file was:

03/05 10:44:33.963: [amf] DEBUG: amf_state_operational(): OGS_EVENT_NAME_SBI_CLIENT (../src/amf/amf-sm.c:81)
{"type":"/nnssf-nsselection/v2","title":"Cannot find NSI by S-NSSAI[SST:1 SD:0x1]","status":403,"instance":"/network-slice-information"}03/05 10:44:33.963: [amf] ERROR: [imsi-001010000000001] HTTP response error [403] (../src/amf/nnssf-handler.c:63)

Then, based on Open5GS Issue #859, I modified my nssf.yaml file and added the SD information. However, after this modification, I encountered a new error in amf.log:

03/05 11:14:45.102: [amf] DEBUG: amf_state_operational(): OGS_EVENT_NAME_SBI_CLIENT (../src/amf/amf-sm.c:81)
{"title":"(NF discover) No NF-Instance [nsmf-pdusession:AMF]","status":400}03/05 11:14:45.102: [amf] ERROR: [1:0] No SmContextCreateError (../src/amf/nsmf-handler.c:192)

I suspected an issue with the SMF, so I checked its status and found that it was not running:

open5gs-smfd.service - Open5GS SMF Daemon
     Loaded: loaded (/lib/systemd/system/open5gs-smfd.service; enabled; vendor preset: enabled)
     Active: activating (auto-restart) (Result: exit-code) since Tue 2025-03-04 16:46:05 CST; 1s ago
    Process: 7259 ExecStart=/usr/bin/open5gs-smfd -c /etc/open5gs/smf.yaml (code=exited, status=255/EXCEPTION)
   Main PID: 7259 (code=exited, status=255/EXCEPTION)
        CPU: 23ms

Mar 04 16:42:34 a systemd[1]: open5gs-smfd.service: Main process exited, code=exited, status=255/EXCEPTION
Mar 04 16:42:34 a systemd[1]: open5gs-smfd.service: Failed with result 'exit-code'.

So, is this issue caused by the SMF? How can I properly establish the PDU session?

Setup Details

The setup consists of four virtual machines, each running Ubuntu 22.04. The details are as follows:

1、Open5GS Control Plane (5GC C-Plane): IP Address: 192.168.83.131
2、Open5GS User Plane (5GC U-Plane): IP Address: 192.168.83.130
3、srsRAN Project ZMQ RAN (gNodeB): IP Address: 192.168.83.136
4、srsRAN 4G ZMQ UE (NR-UE): IP Address: 192.168.83.137

Actual Behaviour

1、The following output appears on the srsUE terminal:

a@a:~/srsRAN_4G/build/srsue$ sudo ./src/srsue ue_zmq.conf
[sudo] password for a: 
Reading configuration file ue_zmq.conf...

Built in Release mode using commit ec29b0c1f on branch master.

Opening 1 channels in RF device=zmq with args=tx_port=tcp://192.168.83.137:2001,rx_port=tcp://192.168.83.136:2000,base_srate=23.04e6
Supported RF device list: zmq file
CHx base_srate=23.04e6
Current sample rate is 1.92 MHz with a base rate of 23.04 MHz (x12 decimation)
CH0 rx_port=tcp://192.168.83.136:2000
CH0 tx_port=tcp://192.168.83.137:2001
Current sample rate is 23.04 MHz with a base rate of 23.04 MHz (x1 decimation)
Current sample rate is 23.04 MHz with a base rate of 23.04 MHz (x1 decimation)
Waiting PHY to initialize ... done!
Attaching UE...
Random Access Transmission: prach_occasion=0, preamble_index=0, ra-rnti=0x39, tti=174
Random Access Complete.     c-rnti=0x4601, ta=0
RRC Connected
Received RRC Release

2、Logs from UE:
ue.log

3、Logs from gNB:
gnb.log

4、Logs from AMF:
amf.log

Configuration Files:
open5gs.zip
5、amf.yaml(On Open5GS 5GC C-Plane)

logger:
  file:
    path: /var/log/open5gs/amf.log
  level: trace   # fatal|error|warn|info(default)|debug|trace

global:
  max:
    ue: 1024  # The number of UE can be increased depending on memory size.
#    peer: 64

amf:
  sbi:
    server:
      - address: 127.0.0.5
        port: 7777
    client:
#      nrf:
#        - uri: http://127.0.0.10:7777
      scp:
        - uri: http://127.0.0.200:7777
  ngap:
    server:
      - address: 192.168.83.131
  metrics:
    server:
      - address: 127.0.0.5
        port: 9090
  guami:
    - plmn_id:
        mcc: 001
        mnc: 01
      amf_id:
        region: 2
        set: 1
  tai:
    - plmn_id:
        mcc: 001
        mnc: 01
      tac: 1
  plmn_support:
    - plmn_id:
        mcc: 001
        mnc: 01
      s_nssai:
        - sst: 1
          sd: 000001
  security:
    integrity_order : [ NIA2, NIA1 ]
    ciphering_order : [ NEA0, NEA1, NEA3 ]
    #integrity_order : [ NIA2, NIA1, NIA0 ]
    #ciphering_order : [ NEA0, NEA1, NEA2 ]
  network_name:
    full: Open5GS
    short: Next
  amf_name: open5gs-amf0
  time:
#    t3502:
#      value: 720   # 12 minutes * 60 = 720 seconds
    t3512:
      value: 540    # 9 minutes * 60 = 540 seconds

6、nrf.yaml(On Open5GS 5GC C-Plane)

logger:
  file:
    path: /var/log/open5gs/nrf.log
  level: debug   # fatal|error|warn|info(default)|debug|trace

global:
  max:
    ue: 1024  # The number of UE can be increased depending on memory size.
#    peer: 64

nrf:
  serving:  # 5G roaming requires PLMN in NRF
    - plmn_id:
        mcc: 001
        mnc: 01
  sbi:
    server:
      - address: 127.0.0.10
        port: 7777

7、smf.yaml(On Open5GS 5GC C-Plane)

logger:
  file:
    path: /var/log/open5gs/smf.log
  level: debug   # fatal|error|warn|info(default)|debug|trace

global:
  max:
    ue: 1024  # The number of UE can be increased depending on memory size.
#    peer: 64

smf:
  sbi:
    server:
      - address: 127.0.0.4
        port: 7777
    client:
#      nrf:
#        - uri: http://127.0.0.10:7777
      scp:
        - uri: http://127.0.0.200:7777
  pfcp:
    server:
      - address: 192.168.83.131
    client:
      upf:
	- address: 192.168.83.130
	  dnn: internet
  gtpu:
    server:
      - address: 192.168.83.131
  metrics:
    server:
      - address: 127.0.0.4
        port: 9090
  session:
    - subnet: 10.45.0.0/16
      gateway: 10.45.0.1
      dnn: internet
#      gateway: 2001:db8:cafe::1
  dns:
    - 8.8.8.8
    - 8.8.4.4
  mtu: 1400
  info:
    - s_nssai:
        - sst: 1
          sd: 000001
          dnn:
            - internet

8、nssf.yaml(On Open5GS 5GC C-Plane)

logger:
  file:
    path: /var/log/open5gs/nssf.log
#  level: info   # fatal|error|warn|info(default)|debug|trace

global:
  max:
    ue: 1024  # The number of UE can be increased depending on memory size.
#    peer: 64

nssf:
  sbi:
    server:
      - address: 127.0.0.14
        port: 7777
    client:
#      nrf:
#        - uri: http://127.0.0.10:7777
      scp:
        - uri: http://127.0.0.200:7777
      nsi:
        - uri: http://127.0.0.10:7777
          s_nssai:
            sst: 1
            sd: 000001

9、upf.yaml(On Open5GS 5GC U-Plane)

logger:
  file:
    path: /var/log/open5gs/upf.log
  level: debug   # fatal|error|warn|info(default)|debug|trace

global:
  max:
    ue: 1024  # The number of UE can be increased depending on memory size.
#    peer: 64

upf:
  pfcp:
    server:
      - address: 192.168.83.130
    client:
#      smf:     #  UPF PFCP Client try to associate SMF PFCP Server
#        - address: 127.0.0.4
  gtpu:
    server:
      - address: 192.168.83.130
  session:
    - subnet: 10.45.0.0/16
      gateway: 10.45.0.1
      dnn: internet
      dev: ogstun
      gateway: 2001:db8:cafe::1
  metrics:
    server:
      - address: 127.0.0.7
        port: 9090

10、gnb_zmq.yaml
gnb_zmq_yaml.txt

11、ue_zmq.conf
ue_zmq_conf.txt

12、pcap
pcap.zip

13、webui

[acetcom]

@PsArzzz

Your smf.conf contains a TAB on lines 26 and 27, which causes the YAML configuration to be incorrect.

 21   pfcp:
 22     server:
 23       - address: 192.168.83.131
 24     client:
 25       upf:
 26     - address: 192.168.83.130
 27       dnn: internet

For reference, if this issue is not suspected to be an Open5GS problem, please post your question in the Discussion section.

Thanks a lot!
Sukchan

[PsArzzz]

Thank you very much for your help. Sorry for taking up your time with such a small issue.