Comment 1 for bug 1392104

It explains how to use the vbox VMs to deploy Openstack in the Operator Training Guide, chapters 5. Controller Node Lab, 8. Network Node Lab and 11. Compute Node Lab.

The bug report is valid, since the Operator Training Guide is clearly not the "next" section - moreover the whole training guide could benefit from an update.

Anyway if your target is to deploy an Openstack installation on VMs testbed, I suggest you to follow the updated installation guide for Ubuntu (juno-based) and not the Operator Training Guide "Lab" (icehouse-based), just giving a look to how to use the host only connections in vbox (described in the Training guide) to emulate the different networks described in the installation guide.
If you need working floating IP, when you install neutron on network node you should also modify the /etc/network/interfaces with br-ex info as described in 8. Network Node Lab. This is the only difference with the steps described in the installation guide to have Openstack running on 3 VMs