What is a virtual machine, and why are they so useful?

In network virtualization, companies have explored network-as-a-service options and network functions virtualization (NFV), which uses commodity servers to replace specialized network appliances to enable more flexible and scalable services. This differs a bit from software-defined networking, which separates the network control plane from the forwarding plane to enable more automated provisioning and policy-based management of network resources. A third technology, virtual network functions, are software-based services that can run in an NFV environment, including processes such as routing, firewalling, load balancing, WAN acceleration, and encryption.

Verizon, for example, uses NFV to power its Virtual Network Services that enables customers to spin up new services and capabilities on demand. Services include virtual applications, routing, software-defined WANs, WAN optimization and even Session Border Controller as a Service (SBCaaS) to centrally manage and securely deploy IP-based real-time services, such as VoIP and unified communications.

VMs and containers

The growth of VMs has led to further development of technologies such as containers, which take the concept another step and is gaining appeal among web application developers. In a container setting, a single application along with its dependencies, can be virtualized. With much less overhead than a VM, a container only includes binaries, libraries, and applications.

While some think the development of containers may kill the virtual machine, there are enough capabilities and benefits of VMs that keep the technology moving forward. For example, VMs remain useful when running multiple applications together, or when running legacy applications on older operating systems.