Is this really necessary?

In my homelab, I prefer to turn everything up to 11. That means I'm using bonds, bridges, jumbo frames, software-defined networking, etc. Maybe I'm reliving my glory days of working for a large public cloud.

I learned Linux in the Red Hat world, so Debian/Ubuntu networking has always struck me as a bit fiddly compared to Red Hat. In Debian or Ubuntu, IP address changes always seemed to require a reboot, and mistakes frequently led to fixing things from the out-of-band serial console.

But that has less to do with Debian and more to do with the venerable /etc/network/interfaces (ifupdown) method of configuring interfaces. There are other options available in Debian now, and at the moment it seems netplan is the best choice.

And why is that?

• It doesn't block the serial console. No longer will I have to reboot into rescue mode because I screwed up an interfaces file.
• It has a safe way of previewing changes (netplan generate).
• It integrates with systemd.

Working Netplan config file from my lab

cat /etc/netplan/01-ovs.yaml
network:
  version: 2
  renderer: networkd
  ethernets: # bonded interfaces
    eth0:
      mtu: 9000 # jumbo frame
    eth1:
      mtu: 9000
  bonds:
    bond0:
      mtu: 9000
      interfaces: [eth0,eth1]
      openvswitch:
        lacp: active # LACP bonding
        other-config:
          lacp-time: fast
          bond-rebalance-interval: 0
      parameters:
        mode: balance-tcp

  bridges:
    ovsbr0:
      interfaces: [bond0]
      mtu: 9000
      openvswitch:
        external-ids:
            iface-id: my_hostname

  vlans:
    stor16:
      id: 16
      link: ovsbr0
      mtu: 9000
      openvswitch: {}
      addresses:
        - 192.168.64.24/28

    pxe32:
      id: 32
      link: ovsbr0
      mtu: 1500
      openvswitch: {}

    mgmt64:
      id: 64
      link: ovsbr0
      mtu: 9000
      openvswitch: {}
      addresses:
        - 192.168.64.6/28
      routes:
        - to: default
          via: 192.168.64.1

    lab98:
      id: 98
      link: ovsbr0
      mtu: 9000
      openvswitch: {}

    lb224:
      id: 224
      link: ovsbr0
      mtu: 1500
      openvswitch: {}

Goodbye, /etc/network/interfaces! I won't miss you.

References

• Netplan integration tests for OVS config - Gives you an idea of how the netplan files are translated into OVS commands.
• Github issue for OVS netplan docs - Not a perfect rendering of config, but it should help get you on the right track.