At Prophecy, we make extensive use of KVM Virtualization on CentOS6. A VM host can have multiple bridge interfaces (each on a separate VLAN) on which we can run virtual machines.
This is a companion discussion topic for the original entry at https://www.funkypenguin.co.nz/note/2015/04/17/automatically-create-vlan-bridge-interfaces-for-kvm-on-rhelcentos-6.html