netplan not bringing up vlans in ubuntu 20

[Rory Toma]

Here is a shortened version of my netplan file which works in 18.04(I actually have 42 bridges/vlans) On ubuntu 18.04, when I reboot, brctl shows that all my bridges have been assigned a bridge id and have a vlan interface associated with it.

On 20.04, a random 22 (always 22) would have a valid bridge id and an inteface with vlan associated with it.

# This file describes the network interfaces available on your system
# For more information, see netplan(5).
network:
  version: 2
  renderer: networkd
  ethernets:
    eno2:
      optional: true

  bridges:
# 10.66.12.0/22 - dev
    br212:
      interfaces: [vlan212]
      macaddress: "00:20:3e:42:0f:19"
      dhcp4: true

# 10.5.0.0/16 - cert
    br105:
      interfaces: [vlan105]
      dhcp4: no

  vlans:
    vlan105:
      accept-ra: no
      id: 105
      link: eno2

    vlan16:
      accept-ra: no
      id: 16
      link: eno2

# 172.16.0.0/16 - sandbox
    br16:
      interfaces: [vlan16]
      dhcp4: no

    vlan212:
      accept-ra: no
      id: 212
      link: eno2

[Rory Toma (pfworks)]

Adding ipv6.disable=1

to my grub makes this work. Is there some kind of ipv6 setting I'm missing in this file?

[Oliver (ciwi)]

I'm experiencing a similar problem after upgrading from Ubuntu 18.04 to 20.04. On Ubuntu 18.04 the config is working just fine.
On Ubuntu 20.04 running brctl shows that the bridges don't have any interfaces. After using 'brctl addif' to add the interface (as specified with netplan) manually, the bridges work. Simply disabling ipv6 via grub didn't solve the problem.

Here's my config:

network:
  version: 2
  ethernets:
    eth0:
      addresses:
      - 192.168.100.215/24
      gateway4: 192.168.100.1
      match:
        macaddress: 9c:b6:54:85:XX:XX
      mtu: 1500
      nameservers:
        addresses:
        - 192.168.100.6
        search:
        - maas
      set-name: eno1
    eth1:
      match:
        macaddress: 9c:b6:54:85:XX:XX
      mtu: 1500
      set-name: eno2
    eth2:
      match:
        macaddress: 2c:44:fd:8f:XX:XX
      mtu: 1500
      set-name: ens1f0
    eth3:
      match:
        macaddress: 2c:44:fd:8f:XX:XX
      mtu: 1500
      set-name: ens1f1
    eth4:
      match:
        macaddress: d8:9d:67:22:XX:XX
      mtu: 1500
      set-name: ens2f0
    eth5:
      match:
        macaddress: d8:9d:67:22:XX:XX
      mtu: 1500
      set-name: ens2f1
  vlans:
    vlan.110:
        id: 110
        link: eth0
    vlan.32:
        id: 32
        link: eth0
    vlan.1:
        id: 1
        link: eth0
    vlan.112:
        id: 112
        link: eth1
  bridges:
    br-mgmt:
        interfaces: [vlan.110]
        parameters:
          stp: false
          forward-delay: 0
        addresses: [ 192.168.110.205/24 ]
    br-vxlan:
        interfaces: [vlan.32]
        parameters:
          stp: false
          forward-delay: 0
        addresses: [ 192.168.32.205/24 ]
    br-vlan:
        interfaces: [vlan.112]
        parameters:
          stp: false
          forward-delay: 0
        addresses: []
    br-storage:
        interfaces: [vlan.1]
        parameters:
          stp: false
          forward-delay: 0
        addresses: [ 10.0.3.205/24 ]

[Patrik Arlos (pal-arlos)]

The problem is also present in Ubuntu 22.04LTS. Disable ipv6, and you can get >24 VLANs.

[Lukas Märdian (slyon)]

Can you please provide debug logs of systemd-networkd [1], so we can see what exactly is going on here?

Enable systemd-networkd debugging

mkdir -p /etc/systemd/system/systemd-networkd.service.d/
Create Drop-In /etc/systemd/system/systemd-networkd.service.d/10-debug.conf with following content:

[Service]
Environment=SYSTEMD_LOG_LEVEL=debug
And restart systemd-networkd service:

systemctl daemon-reload
systemctl restart systemd-networkd
journalctl -b -u systemd-networkd

[1] https://gist.github.com/rkalkani/817edb3d335d7bc17857be81c746e9c9

[Launchpad Janitor (janitor)]

[Expired for netplan because there has been no activity for 60 days.]