Evolutionary changes are occurring within the campus network. One example is the migration from a traditional/Layer 2 access-switch design (with its requirement to span VLANs and subnets across multiple access switches) to a virtual switch-based design. Another is the movement from a design with subnets contained within a single access switch to the routed-access design. This evolvement requires careful planning and deployments. Hierarchical design requirements along with other best practices are detailed throughout the remainder of this book to ensure a successful network.
As the network evolves, new capabilities are added, such as virtualization of services or mobility. The motivations for introducing these capabilities to the campus design are many. The increase in security risks, the need for a more flexible infrastructure, and the change in application data flows have all driven the need for a more capable architecture. However, implementing the increasingly complex set of business-driven capabilities and services in the campus architecture can be challenging if done in a piece meal fashion. Any successful architecture must be based on a foundation of solid design theory and principles. For any enterprise business involved in the design and operation of a campus network, the adoption of an integrated approach based on solid systems design principles, is a key to success.