Cisco CID Exam Certification Guide

Cisco CID Exam Certification Guide

by Mike Crane, Reggie Terrell

The only Cisco-approved study guide for the CCDP CID Exam.

  • The only Cisco-endorsed study guide for the Cisco Internetwork Design Exam.
  • Includes review of all concepts covered on the exam for designing complex routed and switched networks
  • Accompanying CD-ROM containing unique questions and sample tests to help readers identify and master areas


The only Cisco-approved study guide for the CCDP CID Exam.

  • The only Cisco-endorsed study guide for the Cisco Internetwork Design Exam.
  • Includes review of all concepts covered on the exam for designing complex routed and switched networks
  • Accompanying CD-ROM containing unique questions and sample tests to help readers identify and master areas of weakness
  • Extensive use of chapter quizzes and end-of-chapter questions

The only Cisco-endorsed study guide for the Cisco Internetwork Design Exam #640-025, Cisco CID Exam Certification Guide covers all of the major topic areas and objectives for the exam. Organized to help you make the most of your study time, this book focuses on review of the concepts involved in advanced network design, principles of network-layer including addressing, traffic management, and performance considerations.

Foundation Summary sections concisely outline major concepts for quick reference while chapter-opening quizzes enable you to evaluate your knowledge of chapter topics. Scenario-based exercises and chapter-ending review questions reinforce retention and recall of exam topics. Finally, practice questions on the companion CD-ROM enable you to build and take random sample tests.

Product Details

Cisco Press
Publication date:
CCNP/Ccdp Certification and Training Series
Product dimensions:
7.74(w) x 9.46(h) x 1.90(d)

Read an Excerpt

Chapter 1: Design Overview

Foundation Topics

Designing an internetwork requires a certain mix of art and science. Design purists can spend hours debating the merits of one design versus another, but in the real world, issues of selfinterest, background, pride, politics, and personal ego sometimes play a role in the acceptance of the design process.

For test purposes, the CCDP candidate need only be concerned with matching the business and technical requirements to the engineering, availability, time, and cost constraints. The successful network design marries the best technical solution with the needs of the business.

With the advent of e-commerce and e-business, companies face increasingly complex challenges to deliver profit to the, shareholders and value, to the customers. Their requirements for network performance are becoming more and more demanding. Add those requirements to the changing technical issues of the day, and it is easy to see why the task of CCDP is a very demanding professional assignment. In addition to having a strong technical foundation, the CCDP must articulate technical ideas to a primarily nontechnical audience. The CCDP must display a great deal of versatility. Indeed, through the life cycle of a network design, the CCDP can expect to serve in the role of project manager, consultant, integrator, technical liaison, troubleshooter, and problem solver.

Defining the Problem

A design cannot provide an effective solution to a problem that has not been defined. The CCDP who attempts to design a network before the problem is understood will be as successful as a painter who attempts to paint a moving bus. The design will never satisfy the customer, because there is no general agreement on what was needed in the first place.

No problem-no solution!

Know problem-know solution!

The CCDP's first mission is to define the problem. All design requests start with a problem as perceived by someone.

After the problem has been defined, the business requirements must be stated and needs must be prioritized. Then a technical solution can be implemented. A good network design is optimized to meet the requirements of the business at hand. Therefore, a design that is ideal for one business might be woefully lacking for another. One business might have higher security concerns, and another business might be more concerned about disaster recovery. Still another business might share these concerns but might not have the available funds to implement those features. For each client, there is an optimum design that provides a best-fit solution for his or her situation and circumstances.

Internetwork Design Goals

Designing an internetwork can be a challenging task. Despite improvements in equipment performance and media capabilities, internetwork design is becoming more difficult. The trend is toward increasingly complex environments involving multimedia, multiple protocols, and interconnections to networks beyond an organization's domain of control. To render a successful design, the CCDP must realize stated objectives while designing the internetwork.

Here are the goals of internetwork design:

  • Functionality
  • Scalability
  • Adaptability
  • Manageability
  • Cost-effectiveness
The CCDP should realize that these goals are interrelated and must strike a balance to ensure an optimum design. As an example of the balance that is needed, let's look at the relationship between the goals of network design. Of course, it would be desirable to have adaptability and scalability incorporated into the network design. However, if an abundance of adaptability and scalability exists, the design might be very expensive and might compromise the goal of rendering a cost-effective solution.

The foremost goal of an internetwork design is a working system that meets a client's business and technical objectives. Of all the goals listed, there can be no flexibility on this one. The design's success will ultimately be measured by whether the network works. The design should ensure adaptability and compatibility between old and new technologies. The design should allow scalability and flexibility as the client's business and technical requirements change. Although the design should be efficient, it should also be predictable enough to allow others to manage and troubleshoot. Even though the CCDP will understandably want to display brilliance when designing the network, it is important to keep in mind that the network design must be straightforward enough for other network personnel to grasp its concepts.

Of all the goals listed, the one the other goals must be compared is cost. The CCDP must always strike a balance with the other goals in regard to cost. In a perfect world, network design would allow each user to have voice, video, and data on the desktop. Companies, which have profit as one of their business requirements, would not want to use the fastest technology available if the price was unreasonable. The CCDP must be careful to consider cost as the most important metric. An extravagant design might look good on the dream board but, when implemented, would be wasteful and could represent a stranded investment.

If the design meets the criteria for functionality, scalability, and technological advancement while satisfying the all-important metric of cost, the design should be considered a success.

Seven Steps for Designing Internetworks

Figure 1-2 shows a recommended methodology for designing a network. The first three steps should remain static, but the remaining steps will require revisions as dictated by the business's changing needs and requirements.

The following steps are recommended for designing internetworks:

  1. Gather information
  2. Analyze requirements
  3. Develop the internetwork structure
  4. Estimate network performance
  5. Assess costs and risks
  6. Implement and monitor the network

Gather Information

The first step in network design should involve data gathering. Learn about the corporate structure. Find out what applications are being used and what plans exist in the future for change. Obtain a baseline of current network performance. Determine who will play a key role in the decision-making process. Find out how the customer assigns authority with regard to information resources. Do your best to understand the customer and their needs.

The best source of information about performance requirements is the people who use the system. Be sure to include user groups to ensure that no one is left out of the design process.

Analyze Requirements

Determine the customer's business requirements. As soon as you understand the business goals, you can determine the type of technology that is needed. Determine the network availability requirements and the acceptable mean time between failures. Each customer will have a different definition of availability. Adding more resources can increase availability. However, resources increase cost. At some point, greater availability yields a lower output because of the increased cost of providing it. Internetwork design provides the greatest availability for the least cost....

Meet the Author

Mike Crane, CCIE #5531, CCNP/DP, is currently employed with Timebridge Technologies as a Network Architect. Prior to Timebridge, Mike was a Senior Telecommunications Engineer where he designed a multiservice technologies network, which included IP/TV and Voice/IP/Frame using Cisco IP Phones. Mike has a vast amount of experience in the installation and design of local and wide area networks, installation and support of firewalls, routers, switches, CSU/DSUs, multiplexors, and various other equipment.

Reggie Terrell, CCNP/DP, is currently employed with Science Applications International Corp. as a Senior Telecommunications Engineer, and is also the Enterprise Systems Engineer for System Source, a Cisco Premier Partner. Reggie has an A.A. in Engineering, a B.S. in Computer Science, and an M.S. in Telecommunications from the University of Maryland.

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