ULCL multi-UPF: "Mod CreateURR error: file exists" on I-UPF when attaching UE

Q/A
,
#1

Hi, I am testing ULCL with a multi-UPF setup in free5GC v4.0.1 + UERANSIM v3.2.7, and I found a persistent problem related to Mod CreateURR error: file exists on I-UPF.

Environment

  • free5GC: v4.0.1
  • UERANSIM: v3.2.7
  • OS: Ubuntu 20.04.6 LTS
  • gtp5g: 0.9.14

Topology:

  • Path 1: gNB1 → I-UPF1 → PSA-UPF1
  • Path 2: gNB2 → I-UPF2 → PSA-UPF2
  • MEC1 and MEC2 for local breakout through I-UPF1 and I-UPF2(ULCL)
  • Each path uses a different S-NSSAI

Problem
When attaching UE (either in Path 1 or Path 2), sometimes I-UPF shows:
[ERRO][UPF][PFCP][LAddr:<IUPF_IP>][CPNodeID:<SMF_IP>] Mod CreateURR error: file exists
When this happens, the PSA-UPF for that path has no New session [INFO] instead.

#2

Hi, can you give us more detail pcap/log, and all of your configuration upfcfg.yaml, smfcfg.yaml and uerouting.yaml, thanks!

#3

Hey williamlin0518,

Thanks for your reply.
I Deploy gNB1, gNB2, 5GC, I-UPF1, I-UPF2, PSA-UPF1, PSA-UPF2, MEC1, MEC2 on separate VMs and I have uploaded the requested files and logs to gist for better readability:

Thanks a lot for your assistance.