Non-3GPP access to N3IWF fails: Dial to UPF failed

Q/A
,
#1

It seems the N3IWF can’t connect to UPF, here are some relevant logs:

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I am using NWu-Non3GPP-5GC to attempt to connect to the N3IWF. The current network setup is:

192.168.33.6: NWu emulator / UERANSIM UE
192.168.33.5: free5GC (N3IWF enabled) / UERANSIM gNB

I have tested and successfully established a connection from UERANSIM UE (192.168.33.6) to UERANSIM gNB (192.168.33.5) to free5GC (192.168.33.5). However, when attempting to connect to the N3IWF (192.168.33.5) using the NWu emulator (192.168.33.6), N3IWF throws an error trying to connect to the UPF.

Since the error does not occur when the gNB connects to the UPF, I assume the UPF is configured properly. Additionally, since the NWu emulator reaches state 7/7, I assume it is also not configured incorrectly. Therefore, I suspect a mistake in config/n3iwfcfg.yaml. However, I am not sure where.

config/n3iwfcfg.yaml:

info:
  version: 1.0.5
  description: N3IWF initial local configuration

configuration:
  N3IWFInformation:
    ...

  # --- N2 Interfaces ---
  AMFSCTPAddresses: # the IP list of N2 interfaces (SCTP) on AMF when using NGAP
    - IP:
        - 192.168.33.5
      Port: 38412
  NASTCPPort: 20000 # TCP port which the NAS listens on

  # --- Nwu Interfaces ---
  IKEBindAddress: 192.168.33.5 # Nwu interface  IP address (IKE) on this N3IWF
  IPSecTunnelAddress: 11.0.0.1 # Tunnel IP address of XFRM interface on this N3IWF
  UEIPAddressRange: 11.0.0.0/24 # IP address pool allocated to UE in IPSec tunnel
  XFRMInterfaceName: xfrmi # Prefix of XFRM interface name created by N3IWF
  XFRMInterfaceID: 1 # XFRM interface if_id for IPSec routing (Any value except to 0, default value is 7 if not defined)

  # --- N3 Interfaces ---
  GTPBindAddress: 192.168.33.5 # IP address of N3 interface (GTP) on this N3IWF

  FQDN: n3iwf.free5gc.org # FQDN of this N3IWF

  # --- Security ---
  ...

logger: # log output setting
  enable: true # true or false
  level: debug # how detailed to output, value: trace, debug, info, warn, error, fatal, panic
  reportCaller: false # enable the caller report or not, value: true or false

I assumed the error is because of GTPBindAddress; however, I don’t understand what to change it to - the N3 interface connects to the UPF which should be accessible at 192.168.33.5 (I’ve also tried leaving it as 127.0.0.1 which should also work, but I get the same error).

Additionally, I have confirmed that the UPF is in fact accessible at the port mentioned, through sudo netstat -nlp | grep 2152:

udp        0      0 192.168.33.5:2152       0.0.0.0:*                           76032/./bin/upf

If it helps, here is the command I used to run the NWu emulator: (I have confirmed that the arguments match the working free5gc-ue.yaml file)

sudo python3 nwu_emulator.py -s 192.168.33.6 -d 192.168.33.5 -a internet -I 208930000000003 -M 208 -N 93 -K 8baf473f2f8fd09487cccbd7097c6862 -P 8e27b6af0e692e750f32667a3b14605d -T NWU -F

Please let me know of any other information that may help fix this issue, and thank you so much for the help!

#2

Hi,
We are working on it, thanks for questioning.

#3

Update: I was able to resolve this issue by changing AMFSCTPAddresses and ngapIpList back to the default (127.0.0.18), so it seems the main issue is that N3IWF and AMF conflict when running on the same machine. Not sure if this is an issue or if it’s expected behavior.

#4

Hi,
According to your update information, this is our answer:

N3IWF and AMF can run on the same machine indeed

And followings are some replies:

  1. Since you are using ni3wf, gNB is unnecessary.
  2. n3iwfcfg.yaml should look like:
info:
  version: 1.0.5
  description: N3IWF initial local configuration

configuration:
  N3IWFInformation:
    ...

  # --- N2 Interfaces ---
  AMFSCTPAddresses: # the IP list of N2 interfaces (SCTP) on AMF when using NGAP
    - IP:
        - 127.0.0.18
      Port: 38412
  NASTCPPort: 20000 # TCP port which the NAS listens on

  # --- Nwu Interfaces ---
  IKEBindAddress: 192.168.33.5 # Nwu interface  IP address (IKE) on this N3IWF
  IPSecTunnelAddress: 10.0.0.1 # Tunnel IP address of XFRM interface on this N3IWF
  UEIPAddressRange: 10.0.0.0/24 # IP address pool allocated to UE in IPSec tunnel
  XFRMInterfaceName: xfrmi # Prefix of XFRM interface name created by N3IWF
  XFRMInterfaceID: 1 # XFRM interface if_id for IPSec routing (Any value except to 0, default value is 7 if not defined)

  # --- N3 Interfaces ---
  GTPBindAddress: 127.0.0.33 # IP address of N3 interface (GTP) on this N3IWF
  ...

Other free5GC settings you can check free5GC user guide.
Please modify your config and run it again, if the program still has errors, we are willing to answer.

#5
#6

Hi ,
since there haven’t been any replies from you, this topic is closed by admin.
If you have further questions about this topic, please create another topic or message the admin.
Thanks.

Admin