Host-side Link Bonding

Linux networking has long supported bonding, the ability to use multiple links simultaneously. Netlab supports bonding with LACP through the lag module, this plugin adds support for the other bonding modes (that don’t require any special configuration on peers)

Using the Plugin

Add plugin: [ bonding ] to the lab topology.
Include the bonding.ifindex attribute in any links that need to be bonded

Supported attributes

The plugin adds the following attributes defined at global, node or interface level:

bonding.mode (string, one of active-backup, balance-tlb, or balance-alb) – the bonding mode to use, default active-backup

Additional interface level attributes:

bonding.ifindex (int,mandatory) – the interface index for the bonding device; links with matching ifindex are bonded together
bonding.primary (bool) – optional flag to mark this interface as primary, default False. If none of the interfaces are marked as primary, the selection is left to the Linux default behavior

Caveats

The plugin uses the ip command to create bond devices and add member links; in case of Linux VMs that are not Ubuntu, the plugin attempts to install this command when not available. This installation uses apt-get which may not work on some Linux VMs

Examples

Connect a host to a pair of switches using active-backup bonding

plugin: [ bonding ]

bonding.mode: active-backup  # Default

vlans:
  v1:

groups:
  _auto_create: True
  hosts:
    members: [ h1 ]
    device: linux
  switches:
    members: [ s1, s2 ]
    module: [ vlan ]

links:
- s1:
  s2:
  vlan.trunk: [ v1 ]

# Bonded interfaces eth1/eth2
- s1:
  h1:
    bonding.ifindex: 1
- s2:
  h1:
    bonding:
      ifindex: 1
      primary: True  # Use this interface as primary

Note how there are no bonding specific modules enabled on the switches