There is no perfect design, but every design must serve a purpose..

That purpose is shaped by multiple constraints: budget, SLAs, high availability, security and regulatory requirements, as well as the technical teams responsible for operating the network.

The design may also need to serve a transitional purpose — for example, supporting a merger or acquisition while different environments are progressively integrated.

The information gathered during the Understand phase provides the foundation for the design.

From there, we define the appropriate network scale, select the right technologies and determine the architecture: routing protocols, resiliency, segmentation, Classes of Service and the operational model.

The goal is not to design the most complex network. It is to design the right network for its purpose, constraints and future evolution.

Once the design is ready, it is time to validate it — and determine how it can be executed safely.