Setting up a bond and a bridge in Netplan on Ubuntu Server 20.04

I’m in the process of updating my KVM servers from Ubuntu 18.04 to Ubuntu 20.04. Along with the new version of Ubuntu there’s been some changes in netplan.

What I’ve done is edit the default file created after the Ubuntu Server installation /etc/netplan/00-installer-config.yaml and setup the following:

network:
  bonds:
    bond0:
      interfaces:
      - eno1
      - eno2
      parameters:
        mode: active-backup
  ethernets:
    eno1: {}
    eno2: {}
  version: 2
  bridges:
    br0:
      dhcp4: true
      interfaces:
        - bond0
      mtu: 1500
      parameters:
        stp: false
        forward-delay: 4

This has my two interfaces eno1 and eno2 and created bond0 as an active backup. There’s a few different networking modes you can chose from:

Bond Mode	Description
balance-rr	Round robin network configuration. Packets are send in sequential order from the first connection listed, going down the chain
active-backup	Only the first connection is used, unless it fails, in which case another connection is used
balance-xor	This uses a transmission policy to route between interfaces and provides both load balancing and fault tolerance
broadcast	Not sure why you’d use this – sends data on all interfaces
802.3ad	This is an IEEE standard. It does require switches to support the same protocol. This mode aggregates the connection to provide the benefit of bandwidth from all configured interfaces.
balance-tlb	Manages load between the the network adapters based on demand and availability
balance-alb	Includes both transmission load balancing (balance-tlb) and receive load balancing.

Then, the bridge br0 connects to bond0. This is where you configure the network type – DHCP or static IP. In this case I’m using DHCP as the firewall I have in place manages IP address assignments and it has the server set to a static address. If you want to specify a static IP address in this configuration file, you can do it like below:

network:
  bonds:
    bond0:
      interfaces:
      - eno1
      - eno2
      parameters:
        mode: active-backup
  ethernets:
    eno1: {}
    eno2: {}
  version: 2
  bridges:
    br0:
      addresses:
        - 192.168.10.30/24
      dhcp4: false
      gateway4: 192.168.10.1
      nameservers:
        addresses:
          - 192.168.10.1
          - 192.168.10.2
        search: []
      interfaces:
        - bond0

You can find out more information here:
https://netplan.io/examples

There’s a version of this post for 18.04 here (see the comments with suggested fixes):
https://www.aptgetlife.co.uk/setting-up-a-bond-and-bridge-in-netplan-on-ubuntu-18-04/