Chapter 4. A Virtualization Technologies Primer: Theory

This chapter covers the technology used to build virtualized networks (VNs). As discussed previously, virtualization is not just about IPsec tunnels in the WANit covers a wide range of technology options on routers and switches. There are virtual partitions on routers and switches and protocol extensions that combine to maintain the end-to-end coherency of VNs across a shared infrastructure. We consider virtualization in three main sections:

• Devices How is traffic separation maintained internally to a device? What are the primitives used for Layer 2, Layer 3, or Layer 4 traffic?

• Data path How is traffic separation enforced across a network path? What tools are available to maintain the separation across a network?

• Control plane Because data-path virtualization essentially builds an overlay topology, what changes are needed for routing protocols to function correctly?

This chapter does not cover architectures, topologies, or designs. The purpose of this chapter is to make sure you understand the technology before using it. (The world would be a better place if this principle were universally applied).

The general format for each section of this chapter is to start with a discussion of the protocol technology, highlighting any important details, with some limited configuration examples.