© 2005 Cisco Systems, Inc. All rights reserved. CIT v Module Summary Network functionality is divided into modular layers. These layers help isolate problems and create divisions of labor. A specific troubleshooting process enables you to resolve problems quickly and cost-effectively. Gathering symptoms from network devices, end users, and end systems enables you to create a complete description of a problem. Select the troubleshooting approach based on your skill level and temperament.