Summary

Enterprise network design has evolved throughout the years. A hierarchical approach to network design has proven to deliver the best results in terms of optimizing scalability, improving manageability, and maximizing network availability. When virtualizing the enterprise network, you must maintain all these characteristics. Therefore, the model you use to virtualize the network should follow the basic principles of hierarchy and modularity, described in this chapter, in order to achieve the desired level of resiliency and scalability. Even though the management model for the network will need some adjustments to accommodate for a now-virtualized infrastructure, overall network manageability is expected to improve in a virtualized network.

Before we delve into the technical detail about how a network can best be virtualized, let's understand why enterprises are virtualizing their networks. Chapter 3, "A Basic Virtualized Enterprise" explores some of the business drivers behind the virtualization of enterprise networks and discusses many of the benefits that enterprises perceive from virtualizing their networks. The challenge when virtualizing the campus is much different than that posed by the different variations of logical overlays used in the WAN. The added complexity in the WAN is largely due to the necessary interaction with Service Providers and the additional security requirements imposed by the use of shared networks.

In the same way that we propose basic principles of scalability and resiliency, that can be applied throughout the networks (LAN or WAN), we can also propose basic principles for the virtualization of networks. The architecture describing these principles is covered in our next chatper "A Basic Virtualized Enterprise."