Routing and Switching Essentials v6 Companion Guide is the official supplemental textbook for the Routing and Switching Essentials course in the Cisco Networking Academy CCNA Routing and Switching curriculum. This course describes the architecture, components, and operations of routers and switches in a small network. The Companion Guide is designed as a portable desk reference to use anytime, anywhere to reinforce the material from the course and organize your time.