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14 Chapter 1: Design Overview

unacceptable. Beware of designing redundancy just for the sake of redundancy. Duplicating a
component that has a very low likelihood of failure could represent a stranded environment. The
CCDP must determine the appropriate amount of cost-effective fault tolerance to be included
in a network.

Fire, storms, floods, earthquakes, chemical accidents, and an airplane crash (loss of key staff)
are just a few examples of disasters that can happen that are external to the network that can
impact business.

Establish Priorities for Your Network and Applications

Identify the important business processes, and assign each one a priority. Priorities can be based
on the following levels:

Mission-critical--A network or application outage or destruction that would cause an
extreme disruption to the business, cause major legal or financial ramifications, or threaten
someone's health and safety. The targeted system or data requires significant effort to
restore, or the restoration process is disruptive to the business or other systems.

Important--A network or application outage or destruction that would cause a moderate
disruption to the business, cause minor legal or financial ramifications, or cause problems
with access to other systems. The targeted system or data requires a moderate effort to
restore, or the restoration process is disruptive to the system.

Minor--A network or application outage or destruction that would cause a minor
disruption to the business. The targeted systems or network can easily be restored.

Assess Network Resiliency

Assess the resiliency of the network with regard to the following three levels of availability:
reliable networks, high-availability networks, and nonstop networks. Doing so helps you
prioritize risks, set requirements for higher levels of availability, and identify the mission-
critical elements of your network.

Be sure to evaluate the following areas of the network:

Network links

-- Carrier diversity

-- Local loop diversity

-- Facilities resiliency

-- Building wiring resiliency

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