Information Technology Reference
In-Depth Information
Application
Design
Close Design Interaction
Network
Infrastructure Design
Infrastructure
Services Design
To p - D o w n
Design
Modularize
the Network
Implement
Functional Hierarchy
Logical
Subdivision
Logical
Subdivision
Te c h n o l o g y
Selection
Physical
To p o l o g y D e s i g n
Addressing
Design
Routing
Design
QoS
Design
IP Multicast
Design
Security Design
Figure 1-6
To p - D o w n D e s i g n P r o c e s s
Ta ble 1-10 compares the top-down approach to the bottom-up approach to network design.
Ta b l e 1-1 0
To p - D o w n D e s i g n C o m p a r e d t o B o t t o m - U p D e s i g n
Design
Approach
Benefits
Disadvantages
To p - d o w n
Incorporates the organization's require-
ments. Provides the big picture. The de-
sign meets current and future
requirements.
More time-consuming.
Bottom-
up
The design is based on previous experi-
ence and allows for a quick solution.
May result in inappropriate design.
Organizational requirements are not
included.
Pilot and Prototype Tests
As soon as the design is complete and before the full implementation, it is a best prac-
tice to test the new solution. This testing can be done in one of two ways: prototype or
pilot.
A prototype network is a subset of the full design, tested in an isolated environment. The
prototype does not connect to the existing network. The benefit of using a prototype is
that it allows testing of the network design before it is deployed before affecting a pro-
duction network. When implementing a new technology such as IPsec, you might want to
implement a prototype test before deploying it to the operational network.
 
 
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