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Enb key codes7/15/2023 ![]() ![]() UE Fails to Register/Attach to the NetworkĪssuming while scanning for networks the UE can see the network, but not connect, the most common issues stem from Authentication. Check PLMN is not forbidden on USIM (F-PLMN List).Check the UE you are scanning with is capable of working on the frequencies / bands and duplex mode (TDD or FDD) used by the UE.Check your gNB/eNB is connected to the AMF/MME.If while scanning for the networks on your UE / Phone you’re not seeing your network, there’s a few things to check: If your network is setup there are a variety of reasons your network may not perform correctly / at all when connecting a UE. INFO: eNB-S1 accepted in master_sm module (mme-sm.c:126) INFO: eNB-S1 accepted:3223 in s1_path module (s1ap-lkpath.c:70) If you’re seeing NGAP/S1AP Connection attempts but seeing them rejected by Open5GS, the NGAP/S1AP message show in a packet capture will indicate the rejection reason, as well as in the mme log. Check that the AMF/MME service is started and listening on the interface / IP you’re sending traffic to. If you are seeing the SCTP INIT messages and seeing an ABORT after each one, that suggests the SCTP connection is trying to be established. If you’re not seeing these packets go back and check your network. If you’re confident the service is running and connectivity is able to be established across your transmission network, you should see the SCTP INIT packets in Wireshark. Not all devices / routers support NGAP/S1AP, particularly over the Internet. Note: 3GPP defines SCTP as the transport protocol for NGAP/S1AP traffic (not TCP/UDP). ![]() If you’re not seeing any NGAP/S1AP connection attempts check the gNB/eNB can contact the IP the AMF/MME is on (No firewall / ACLs etc blocking) and that SCTP Traffic is able to be carried across your transmission network. When a UE connects to Open5GS AMF/MME the log shows the presence of a new NGAP/S1AP connection the log at /var/log/open5gs/mme.log: No NGAP/S1AP Connection The log should tell you which section of the yaml file is missing or invalid. The errors you experience may be different, but if a service is failing to start it’s most often due to a misconfiguration issue in one or more of the Open5GS. In the example above we can see the error - no SGW-C GTP-C address is configured in the mme.yaml file, meaning Open5GS MME is failing to start. If your instance doesn’t show this make sure you’re started each service: You should see each of the above services, MME, SGW-C, SMF, AMF, SGW-U, UPF, HSS, PCRF, NRF, SCP, AUSF, UDM, PCF, NSSF, BSF & UDR are all running.
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