Top-down Design Networks should be designed top-down but implemented bottom-up. A good architect starts with the client's goals and waits until the structure is defined before pouring the foundation. A good network architect remains focused on your particular goals, from design through configuration, to ensure that each layer will support those above. Ideally, each layer is independent of the rest and can be upgraded in place. Although existing standards do provide for such modular designs, changes and upgrades are more difficult and expensive toward the bottom of the stack. It is essential, therefore, that your design considers existing and emerging standards at every level.