Static NR-DC with Namespace

Note

Namespace provides an alternative to using a physical machine.

With namespaces, you can simulate isolated network environments on a single machine, making it possible to run both free5GC and free-ran-ue without the need for multiple physical devices.

For detailed namespace implementation, please refer to this implementation article: Namespace-Based GTP5G Conflict Resolution for free5GC and PacketRusher.

Architecture Overview

Since the GTP port and the routing table will get in conflict, we can set up four namespaces for free5GC/Master RAN/Secondary RAN/UE, which means you don't need to bring up real machines.

Here is the deployment of these three namespaces:

free-ran-ue-dc-namespace

A. Prerequisites

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

gtp5g

sudo apt -y update
sudo apt -y install git gcc g++ cmake autoconf libtool pkg-config libmnl-dev libyaml-dev
git clone https://github.com/free5gc/gtp5g
cd gtp5g
make
sudo make install

MongoDB

sudo apt install -y gnupg curl
curl -fsSL https://www.mongodb.org/static/pgp/server-7.0.asc | \
sudo gpg -o /usr/share/keyrings/mongodb-server-7.0.gpg --dearmor
echo "deb [ arch=amd64,arm64 signed-by=/usr/share/keyrings/mongodb-server-7.0.gpg ] https://repo.mongodb.org/apt/ubuntu jammy/mongodb-org/7.0 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-7.0.list
sudo apt update
sudo apt install -y mongodb-org
sudo systemctl enable mongod --now

B. Namespace Setup

Clone and build free-ran-ue

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

Bring up namespaces (under free-ran-ue)
```
make dc-ns-u
```
After using, there is down command to clean up the namespaces:
```
make dc-ns-down
```

C. Configure free5GC

Clone free5GC and build

git clone -j `nproc` --recursive https://github.com/free5gc/free5gc
cd free5gc
make

Modify NF configuration:
- ~/free5gc/config/amfcfg.yaml
  
  Replace ngapIpList IP from 127.0.0.18 to 10.0.1.1:
```
ngapIpList:
  - 10.0.1.1
```
- ~/free5gc/config/smfcfg.yaml
  
  Replace N3 interface's endpoints IP from 127.0.0.8 to your 10.0.1.1:
```
interfaces:
  - interfaceType: N3
    endpoints:
      - 10.0.1.1
```
- ~/free5gc/config/upfcfg.yaml
  
  Replace N6 interface address IP from 127.0.0.8 to 10.0.1.1:
```
gtpu:
  forwarder: gtp5g
  iifList:
    - addr: 10.0.1.1
```

Check IP Forward is enabled

If you have rebooted your machine, remember to run these command with setting your export network interface:

sudo sysctl -w net.ipv4.ip_forward=1
sudo iptables -t nat -A POSTROUTING -o <export network interface> -j MASQUERADE
sudo systemctl stop ufw
sudo iptables -I FORWARD 1 -j ACCEPT

Run free5GC (under free5gc)
```
./run.sh
```
Run webconsole and create a subscriber by default (under free5gc)
```
cd webconsole
./run.sh
```
For creating a subscriber, please refer to: Create Subscriber via Webconsole

Make sure there is a flow rule (e.g. 1.1.1.1/32) under the network slice.

D. Start gNBs

The configuration file config/gnb.yaml has already been set up with the environment values. No need to modify the configuration.

Master-gNB

Enter the Master-RAN namespace (under free-ran-ue)
```
make dc-ns-mran
```

Start Master-gNB

./build/free-ran-ue gnb -c config/gnb-dc-static-master.yaml

Secondary-gNB

Enter the Master-RAN namespace (under free-ran-ue)
```
make dc-ns-sran
```

Start Master-gNB

./build/free-ran-ue gnb -c config/gnb-dc-static-secondary.yaml

E. Start UE

The configuration file config/ue-dc-static.yaml has already been set up with the environment values. No need to modify the configuration.

Enter the UE-namespace (under free-ran-ue)
```
make dc-ns-ue
```

Start UE

./build/free-ran-ue ue -c config/ue-dc-static.yaml

F. ICMP Test

Enter the UE-namespace (under free-ran-ue)
```
make dc-ns-ue
```

Check the ueTun0 interface

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

ping test via Master-gMB

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

ping test 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

Now, both the Master-gNB and Secondary-gNB are running successfully in their respective namespaces. The UE also works well with dual path connections.