Rina-deployment/docs/vlan40-bridge-systemd-networkd.md

Bridge for VLAN 40 with systemd-networkd

Steps to create a persistent bridge br1.40 for VLAN 40 on eth1 using systemd-networkd (systemd 232).

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Your current layout (satbox)

Existing files in /etc/systemd/network/:

• 10- — eth0 (link + network)
• 11-, 12-, 13- — eth0.50, eth0.60, eth0.201 (netdev + network each)
• 20-, 30-, 40- — eth1, eth2, eth3 (link + network)
• 50- — br1 (netdev + network)

New files below use 21- for VLAN 40 on eth1 (eth1.40) and 51- for bridge br1.40 (after 50-br1).

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1. Prerequisites

• Kernel module: VLAN support must be loaded. Ensure 8021q is loaded (often already is if you use VLANs):

  sudo modprobe 8021q
  

  To load at boot (if not already):

  echo 8021q | sudo tee -a /etc/modules-load.d/8021q.conf
  

• Config directory: All configs go under /etc/systemd/network/. Create it if missing:

  sudo mkdir -p /etc/systemd/network
  

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2. Define the VLAN interface (.netdev)

Create a netdev file so systemd-networkd creates the VLAN interface on eth1 at boot.

File: /etc/systemd/network/21-eth1.40.netdev

[NetDev]
Name=eth1.40
Kind=vlan

[Vlan]
Id=40

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3. Define the bridge (.netdev)

Create the bridge device. Same pattern as your existing 50-br1.netdev.

File: /etc/systemd/network/51-br1.40.netdev

[NetDev]
Name=br1.40
Kind=bridge

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4. Attach the VLAN to the bridge (.network)

Use a .network file that matches the VLAN interface and adds it to the bridge.

File: /etc/systemd/network/21-eth1.40.network

[Match]
Name=eth1.40

[Network]
Bridge=br1.40

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5. Configure the bridge (.network)

Optional: assign an IP to the bridge if the host must be on VLAN 40 (e.g. for management or routing). If the bridge is only for VMs, you can omit the address or use a small subnet. Same pattern as your existing 50-br1.network.

File: /etc/systemd/network/51-br1.40.network

[Match]
Name=br1.40

[Network]
Address=192.168.40.254/24

Adjust the address to match your VLAN 40 subnet. Remove the Address= line if you do not want an IP on the host.

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6. Add VLAN to the parent interface (.network)

Edit 20-eth1.network so that eth1 explicitly carries VLAN 40. Your file currently looks like:

[Match]
Name=eth1

[Network]
Bridge=br1

Add VLAN=eth1.40 under [Network] (same pattern as 10-eth0.network, which has VLAN=eth0.50, VLAN=eth0.60, VLAN=eth0.201). After editing:

[Match]
Name=eth1

[Network]
Bridge=br1
VLAN=eth1.40

This ties the VLAN to eth1 so it is created when eth1 is configured. eth1 stays in br1; eth1.40 will be created and then attached to br1.40 by the 21-eth1.40.network file.

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7. Apply and check

1. Restart systemd-networkd:

   sudo systemctl restart systemd-networkd
   

2. Check that the VLAN and bridge exist and the VLAN is in the bridge:

   ip -br link show eth1.40
   ip -br link show br1.40
   ip link show master br1.40
   

3. Optional: check status:

   networkctl status br1.40
   networkctl status eth1.40
   

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8. Deploy the VM on br1.40

After br1.40 is up and has eth1.40 as a port, deploy the VM onto it:

BRIDGE=br1.40 ./deploy-rina-vm.sh

By default the VM is named CUBE. It will get the IP configured in cloud-init/user-data (e.g. 192.168.0.225/24); adjust that file if your subnet or gateway differ. Console: virsh console CUBE.

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File summary

File	Purpose
Edit 20-eth1.network	Add VLAN=eth1.40 under [Network] so eth1 carries VLAN 40
21-eth1.40.netdev	Creates VLAN interface eth1.40 on eth1
21-eth1.40.network	Puts eth1.40 into bridge br1.40
51-br1.40.netdev	Creates bridge br1.40 (after 50-br1)
51-br1.40.network	Optional: IP on br1.40 (e.g. 192.168.40.254/24)

Files are processed in alphanumeric order. Netdevs (21-, 51-) are applied first, then network files; br1.40 exists before 21-eth1.40.network adds the VLAN to it.

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Troubleshooting

• VLAN interface not created: Ensure 8021q is loaded and eth1 is up. Check logs: journalctl -u systemd-networkd -n 50.
• VLAN not in bridge: Ensure the [Match] Name= in 21-eth1.40.network matches the VLAN interface name exactly (eth1.40).
• Changes not applied: Run sudo systemctl restart systemd-networkd and re-check ip link and networkctl.