bonding-config-in-ubuntu

This project is inteded as an experiment to learn about network interface Bonding in Ubuntu.

The aim of the experiment is to combine 4 network interfaces into a sigle link with a single IP address, using the examples found in the Ubuntu Documentation, and Netplan Documentation and to develop a set of Ansible playbooks that automate this process as much as possible.

Testbed

Vagrant and VirtualBox are used to setup a VM called testbed running Ubuntu 22.04 that is configured with 5 network interfaces with static IP adresses. One of these is the service interface with IP 192.168.30.10 by which the VM can be acessed.

The commands below can be used to manage the testbed:

# start
vagrant up

# connect with SSH
vagrant ssh

# suspend
vagrant suspend

# resume
vagrant resume

# stop and delete
vagrant destroy

Playbooks to setup a bond

To configure bonding with Ansible, a file called inventory should contain the IP address of the server, a username with sudo permission and the path to the ssh private key. After that, the set of ansible playbooks can be executed with the ansible-playbook command.

show_interfaces playbook

This playbook is used check how the network is configured on the server and serves as a reference for the setup_bonding playbook. It executes the ip command with the appropiate arguments to print out network interfaces and IP information.

To execute playbook, run:

ansible-playbook playbooks/show_interfaces.yml -i inventory 

setup_bonding playbook

This playbook needs to be provided with the folowing variables:

• interfaces: a comma separated list of interfaces
• bond_ip: a static IP in the CIDR notation
• bond_gateway: default gateway IP

It performs the following tasks:

• Ensures kernel support for bonding in the OS

• Binds the provided interfaces in a new interface called bond0

  Uses the template file templates/netplan-config.j2 to create the /etc/netplan/01-bond-cfg.yaml Netplan configuration file in the server.

  The template defines bond0 with the folowing parameters

  mode: 802.3ad
  bond_lacp_rate: fast
  mii-monitor-interval: 1
  transmit-hash-policy: layer2+3

  and assigns it a static IP address with the provided bond_ip and bond_gateway.

  This configuration uses a combination of Layer 2 (MAC address) and Layer 3 (IP address) information to determine which interface to send traffic over. This allows for a more even distribution of network traffic across all the interfaces in the bond, maximizing bandwidth.

  It also provides fault tolerance by allowing the bond to continue functioning even if some of the interfaces fail or are disconnected. The remaining interfaces in the bond will continue to handle traffic, ensuring uninterrupted connectivity.

• Applies the configuration by executing the netplan apply command

To execute playbook, run:

# replace the placholders with the intended values and run below to setup the bond
ansible-playbook playbooks/setup_bonding.yml \
   -i inventory 
   -e interfaces="if_name_1,if_name_2,if_name_n" \
   -e bond_ip="*.*.*.*/*" \
   -e bond_gateway="*.*.*.*" 

Run on the testbed

Example workflow to configure a 4 interface bond on the testbed:

1. Create a file called inventory and add the testbed access information to it

   touch inventory
   echo "[testbed_server]" > inventory
   echo "192.168.30.10 ansible_user=vagrant ansible_ssh_private_key_file=.vagrant/machines/testbed/virtualbox/private_key" >> inventory

2. Print out the network interfaces and ip information

   ansible-playbook playbooks/show_interfaces.yml \
      --ssh-extra-args="-o StrictHostKeyChecking=no" \
      -i inventory 

3. Configure a bond with the provided interfaces

   ansible-playbook playbooks/setup_bonding.yml \
      --ssh-extra-args="-o StrictHostKeyChecking=no" \
      -i inventory \
      -e interfaces="enp0s9,enp0s10,enp0s16,enp0s17" \
      -e bond_ip="192.168.30.11/24" \
      -e bond_gateway="192.168.30.1" 

4. Print out the network interfaces and ip information again to verify the bond is correctly configured

   ansible-playbook playbooks/show_interfaces.yml \
      --ssh-extra-args="-o StrictHostKeyChecking=no" \
      -i inventory