Information Technology Reference
In-Depth Information
QoS should be enabled on network devices to allow for prioritization of time-sensi-
tive or bandwidth-sensitive applications.
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Ta ble 1- 9 summarizes areas in characterizing the network.
Ta b l e 1- 9
Characterizing the Network
Characteristic
Description
Steps in gathering information
1.
Obtain existing information and documentation
2.
Network audit
3.
Traffic analys is
Primary sources of network audit in-
for mat ion
Existing documentation
Existing network management software
New network management tools
This section describes the top-down approach for network design, reviews pilot and
prototype test networks, and describes the components of the design document. As
part of the Design phase of the PPDIOO methodology, a top-down approach is used
that begins with the organization's requirements before looking at technologies. Net-
work designs are tested using a pilot or prototype network before moving into the
Implement phase.
Key
To p i c
To p - D o w n A p p r o a c h
To p - d o w n d e s i g n j u s t m e a n s s t a r t i n g y o u r d e s i g n f r o m t h e t o p l a y e r o f t h e O S I m o d e l a n d
working your way down. Top-down design adapts the network and physical infrastructure
to the network application's needs. With a top-down approach, network devices and tech-
nologies are not selected until the applications' requirements are analyzed. To complete a
top-down design, the following is accomplished:
Analysis of application and organization requirements
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Design from the top of the OSI reference model
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Define requirements for upper layers (Application, Presentation, Session)
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Specify infrastructure for lower OSI layers (transport, network, data link, physical)
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Gather additional data on the network
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Figure 1-6 shows a top-down structure design process. The design process begins with
the applications and moves down to the network. Logical subdivisions are then incorpo-
rated with specifics.
