For testing some stuff related to MySQL Cluster, port binding and having two network interfaces on the same subnet i needed a bit more than my usual "all nodes on localhost" setup. Looking for a reusable solution i this time did not just simply plug several of my old laptops into the same hup but tried to create a Vagrant setup for this.
This quickly lead to the question how to define multiple network adapters per Vagrant VM. The manual is not too clear about this yet, and the key piece of information is not yet to be seen in the network section but is hiding in the section on port forwarding: the :adapter option.
So to define multiple adapters you need to add :adapter => $value options on each of the vm.network lines, with $value counting up from one, e.g.:
In my case i need both adapters to be on the same IP subnet. Vagrant (or VirtualBox?) is not clever enough for this yet and will create two distinct host-only networks for this, routing and binding works as expected though as the kernels inside the VMs do not care about (and are not even aware of) this.