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9
WAN Design Considerations
This chapter lightly brushes over the business and technical reasons for designing an
internetwork for a customer. This chapter also focuses on some of the issues facing
designers today, including availability, performance, and redundancy. Technology topics
mentioned in this chapter are more thoroughly discussed in other chapters.
Cisco expects design professionals to be able to provide a cost-sensitive solution that meets
customers' requirements for redundancy and performance.
This requires the design
professional to analyze the business and technical requirements for wide-area network
(WAN) designs and to provide the proper solution.
When you're designing most WAN implementations, reliability is the most important goal
because the WAN is often a part of the internetwork.
The question to ask of the company is how important is it that the network be available
7/24/365?
Only from talking with your customers will you be able to make recommendations for
equipment and design. WAN equipment and resources are expensive. The links that connect
the sites are usually monthly recurring charges.
The CID exam tests your knowledge of how these technologies operate and interoperate.
It is expected that a design professional, given specific criteria, can make recommendations
to improve performance utilizing Cisco IOS software features, such as compression,
queuing, and Quality of Service (QoS).
Customers today all have concerns about their networks. Either reliability or availability is
usually the most important, followed by cost. A good WAN design is typically a good
balance of both.
Another concern is the amount of traffic traversing the WAN. What routing protocols are
used across the WAN? Remember, typically WAN links are slow links, so you do not want
to waste the available bandwidth with unnecessary routing updates. You also need to keep
in mind whether you have to interface with legacy systems or standards.
The CID exam also tests your knowledge of how the WAN technologies operate
and interoperate.
87200333.book Page 289 Wednesday, August 22, 2001 2:53 PM