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).

Warning

You cannot combine this plugin with access- or trunk VLANs on the Linux side. More details…

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