N2 and N3 interface configuration for an external RAN

Q/A
#1

Dear Community,

I have correctly installed free5GC following this guide: Installation · free5gc/free5gc Wiki · GitHub .Running CN (./run.sh) on a Virtual Machine, it seems that there is only the N6 interface. I mean, running ifconfig on the console I see only the upfgtp interface (by the way without ipv4 address).

It seems that the N2 (gNB - AMF) and N3 (gNB UPF) interfaces are missing. I’m trying to connect an external RAN (OAI on the server where I have the VM with free5GC).

The questions are:

  1. without the N2 and N3 interfaces, how can I get the gNB of OAI to communicate with free5GC?
  2. Is it normal that with ifconfig I see only upfgtp ? And without ipv4 address?

I have tried several times in modifying ipv4 addresses in the configuration files, but cannot find a solution. I’ m reporting one as an example, I try to change the address of what I think is the N2 interface in the amfcfg.yaml file:

ngapIpList: # the IP list of N2 interfaces on this AMF.
- 10.7.0.50

when I run the CN, I get the following error:
[ERRO][MFA][NGAP] Failed to listen: cannot assign requested address

What am I doing wrong? Why don’t I see the interfaces on ifconfig? How do I communicate an external RAN to free5GC (for example OAI requires the ipv4 address of the AMF in the configuration file)?

Thanks in advance,
Giuseppe

#3

Sorry, there is an error in the “error message”. The correct:
[ERRO][AMF][NGAP] Failed to listen: cannot assign requested address

also, I find, in the master branch the folder:“sample/ran_attach_config”. But the config file are different. Maybe is better for me to use this branch? I need to install again in a different folder?

Thanks in advance,
Giuseppe

#4

Hello @Giuseppe,
I want to know if you have set the free5GC and UERANSIM parameters correctly?
Refer to the free5GC installation tutorial here, I hope it will help you!