Book excerpt: Network design engineers are the backbone of the internetworking world. They are the people responsible for turning concepts into designs. They must take the customer's requirements, budget, and plans for growth and apply design principles to turn ideas into reality. They quietly do this while claiming none of the credit. Designing networks is one of the most challenging and rewarding careers a network engineer can choose. You will have to forge close links with vendors and your customers and deal with installation engineers on a daily basis as they turn your designs into live networks through installation, testing, and handover phases. The Cisco Certified Design Engineer (CCDP) qualification demonstrates your mastery of the latest developments in network design and technologies, including network infrastructure, intelligent network services, and converged network solutions. If you choose to add hands-on qualifications such as CCNA and CCNP to your portfolio of skills, you will be in a unique position to see the network take shape, from planning and design to the final build. You will also be in very high demand by employers or as a consultant.This manual has been written by an expert Cisco engineer who has several years of experience as an employee and as a consultant designing and troubleshooting large corporate networks at an enterprise level. To qualify as a CCDP engineer, you need to pass the foundation CCDA exam, as well as the SWITCH, ROUTE, and ARCH exams. This guide will teach you everything you need to master in order to pass your 642-874 Designing Cisco Network Service Architectures (ARCH) exam, including: - The Cisco Enterprise Architecture Model - The Advanced Enterprise Architecture Model - Campus Infrastructure Best Practices - Virtualization Design Considerations - Designing Advanced IP Addressing - Designing Advanced IP Multicast - ISP Multi-Homing Design - Designing Advanced Routing Solutions - Designing Advanced WAN Services - And much more