Network Virtualization

This chapter describes the importance of device virtualization technologies. It also explains how to configure and verify data path virtualization technologies. Virtual machine is a term you're probably quite familiar with. A virtual machine (VM) is an emulated computer running inside a real computer. To be more precise, a real computer running an operating system (OS) runs a VM that runs its own OS. Confusing, right? Simply put, machine virtualization is the act of running one OS inside of another. The outer or parent OS is the host OS, and the virtual OS is called the guest OS. This setup is often called server virtualization, but that term is a bit misleading because server virtualization isn't unique to servers. The term came about because servers were the earliest machines to be virtualized. But any personal computer made within the past 15 years can run a VM. The host OS runs natively on x86 hardware, or “bare metal.” The host OS contains a software program called a virtual machine monitor (VMM) or hypervisor that creates VMs, which are essentially software-emulated computers consisting of CPU, memory, storage, and networking. The guest OS runs inside the VM. Hypervisors are classified into two types: type-1 and type-2. NFV takes the features and functionality of proprietary network equipment and implements them in VMs. These VMs-or virtual appliances-are called virtual network functions (VNFs).