Upfgtp interface IPv4 address Allocation

Q/A
1

Hello all,

I installed free5gc in Ubuntu 20.04 and Ubuntu 18.04+kernel 5.0.0-23-generic, but I noticed that the upfgtp interface only got allocated an IPv6 address without an IPv4 address in both environments.

upfgtp
upfgtp721×188 25.7 KB

Therefore, my UE of UERANSIM could not ping the external Internet via UPF using GTP/ICMP.
The PDU session was successfully established, and the the UE had an IP(60.60.0.1) in the GTP tunnel.

ueransim
ueransim723×297 45.4 KB

I also tried to install the latest version of gtp5g from GitHub - PrinzOwO/gtp5g: Linux kernel module 5G GTP-U, but it didn’t work, too.

Does anyone have ideas about this issue?

2

Hi @Jason

The upfgtp on my U-Plane VM is also as follows.

# ip addr show
...
4: upfgtp: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000
    link/none 
    inet6 fe80::9b7:6619:eb23:23f5/64 scope link stable-privacy 
       valid_lft forever preferred_lft forever

Tcpdumping upfgtp on the U-Plane confirms that ICMP packets are passing through this interface.

I think that the network needs to be set according to each environment.
Is NAT / NAPT of your U-Plane set properly?

1 Like
4

What was the configuration you used to support IPv4?

Was the update in the upfcfg.yaml? Did you make changes to the upf_config.c or upf_context.c?

3

Hello @s5uishida,

Thank you for the IP address info of upfgtp.
I thought my gtp5g module had a problem, but it was about network address configurations in free5gc and UERANSIM.

5

What network configuration did you do to fix your problem?

I am having the same issue with only having a IPv6 address, but for what I am doing I need an IPv4 address because of the ue or radio only supporting IPv4 (we can’t confirm this yet, but it is the theory).

6

Hi, Jason what changes you make in the upf config file to resolve the issue. Can you please let me know?