30 Chapter 1: Design Overview
Foundation Summary
This section is a collection of tables and figures that provide a convenient review of many key
concepts in this chapter. If you are already comfortable with the topics in this chapter, this
summary might help you recall a few details. If you have just read this chapter, this review
should help solidify some key facts. If you are doing your final preparation before the exam,
these tables and figures are a convenient way to review the day before the exam.
Every network design should anticipate growth and change. The best-managed scalable
internetworks are typically designed following the recommended design steps and using one of
the models recommended by Cisco (see Table 1-2). The hierarchical model (see Tables 1-3 and
1-4) has been successful because it can be applied to any network. For small networks, a tier or
two can be omitted without compromising the model's design goals.
Here are the steps for designing internetworking solutions:
1
Gather information.
2
Analyze requirements.
3
Develop the internetwork structure.
4
Estimate network performance.
5
Assess costs and risks.
6
Implement the network.
7
Monitor the network.
Table 1-2
Design Models
Design Models
Advantages
Disadvantages
Flat earth
Inexpensive and easy to set up
Network does not regulate or
control broadcasts.
Network performance is impacted.
Scalability is limited by the number
of broadcasts. Is not scalable for
medium to large networks.
Star
Easy setup and administration
Allows for a single point of failure.
Does not scale for medium to large
networks.
Ring
Network does not have a single point of failure.
Allows for limited scalability (more than star).
Higher cost
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