Static NR-DC

Caution

Do not start the Master-gNB and Secondary-gNB on the same machine, as this will cause a GTP port conflict.
Do not start the UE on the same machine as free5GC, as this will cause data plane forwarding failures.

There are two options for deployment:

Use separate machines.
Use namespace separation. For details, please refer to Quick Start.

A. Prerequisites

Golang:

free-ran-ue is built, tested and run with go1.24.5 linux/amd64

If Golang is not installed on your system, please execute the following commands:

Install Golang:

wget https://dl.google.com/go/go1.24.5.linux-amd64.tar.gz
sudo tar -C /usr/local -zxvf go1.24.5.linux-amd64.tar.gz
mkdir -p ~/go/{bin,pkg,src}
# The following assume that your shell is bash:
echo 'export GOPATH=$HOME/go' >> ~/.bashrc
echo 'export GOROOT=/usr/local/go' >> ~/.bashrc
echo 'export PATH=$PATH:$GOPATH/bin:$GOROOT/bin' >> ~/.bashrc
echo 'export GO111MODULE=auto' >> ~/.bashrc
source ~/.bashrc

Check Installation. You should see the version information:
```
go version
```

If another version of Golang is installed, please execute the following commands to replace it:

sudo rm -rf /usr/local/go
wget https://dl.google.com/go/go1.24.5.linux-amd64.tar.gz
sudo tar -C /usr/local -zxvf go1.24.5.linux-amd64.tar.gz
source $HOME/.bashrc
go version

B. Clone and Build free-ran-ue

Clone

git clone https://github.com/Alonza0314/free-ran-ue.git

Build
```
cd free-ran-ue
make
```
After building, a binary executable file will be generated in the build folder.

C. Start gNBs

Modify the configuration file for gNBs:

The configuration YAML file template is located at:
- free-ran-ue/config/gnb-dc-static-master.yaml
- free-ran-ue/config/gnb-dc-static-secondary.yaml
Ensure that the information matches your core network settings. For core network settings, please refer to: Start free5GC

Please also pay attention to the xnIp and xnPort field, as these will be used for the Xn-interface between the gNBs.

Also noticed the fields staticNrdc that should be set as true for enabling static NR-DC.
Start gNB:

After configuring the YAML file, execute the binary in the build folder to start gNBs with the specified configuration file:
- Master-gNB:
```
./build/free-ran-ue gnb -c config/gnb-dc-static-master.yaml
```
- Secondary-gNB:
```
./build/free-ran-ue gnb -c config/gnb-dc-static-secondary.yaml
```

D. Start UE

Modify the configuration file for UE:

The configuration YAML file template is located at free-ran-ue/config/ue-dc-static.yaml.

Ensure that the information matches your web console settings, especially the authenticationSubscription section. For web console settings, please refer to: Create Subscriber via Webconsole

To test the dual connectivity feature, there should be at least one flow rule (e.g. 1.1.1.1/32) configured under the subscriber.

Pay attention to the ueTunnelDevice field, as this will be the name of the network interface created later. Also make sure the nrdc section is configure correctly.
Start UE:

After configuring the YAML file,execute the binary in the build folder to start UE with the specified configuration file:
```
./build/free-ran-ue ue -c config/ue-dc-static.yaml
```

E. ICMP Test

After UE has started, a network interface will be available. Use ifconfig to check it:

ifconfig

Expected output included:

ueTun0: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST>  mtu 1500
        inet 10.60.0.1  netmask 255.255.255.255  destination 10.60.0.1
        inet6 fe80::b1e9:2933:3c64:b981  prefixlen 64  scopeid 0x20<link>
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 500  (UNSPEC)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 3  bytes 144 (144.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

ICMP test with ueTun0 via Master-gNB:

ping -I ueTun0 8.8.8.8 -c 5

Expected successful output:

PING 8.8.8.8 (8.8.8.8) from 10.60.0.2 ueTun0: 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=116 time=3.71 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=116 time=4.08 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=116 time=3.82 ms
64 bytes from 8.8.8.8: icmp_seq=4 ttl=116 time=4.25 ms
64 bytes from 8.8.8.8: icmp_seq=5 ttl=116 time=3.77 ms

--- 8.8.8.8 ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4006ms
rtt min/avg/max/mdev = 3.706/3.926/4.252/0.206 ms

ICMP test with ueTun0 via Secondary-gNB:

ping -I ueTun0 1.1.1.1 -c 5

Expected successful output:

PING 1.1.1.1 (1.1.1.1) from 10.60.0.2 ueTun0: 56(84) bytes of data.
64 bytes from 1.1.1.1: icmp_seq=1 ttl=49 time=4.51 ms
64 bytes from 1.1.1.1: icmp_seq=2 ttl=49 time=4.46 ms
64 bytes from 1.1.1.1: icmp_seq=3 ttl=49 time=4.27 ms
64 bytes from 1.1.1.1: icmp_seq=4 ttl=49 time=3.97 ms
64 bytes from 1.1.1.1: icmp_seq=5 ttl=49 time=4.64 ms

--- 1.1.1.1 ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4007ms
rtt min/avg/max/mdev = 3.972/4.371/4.644/0.232 ms