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Track 2 Session 7
1:00 to 2:00 p.m. Wednesday June 18, 2008
A Method for Quantitatively Predicting
the Availability of a Complex Communications Network
Critical communication networks
require high availability; however, their complex architectures make
availability very difficult to predict. High availability strategies
such as the selection of reliable components and redundant
architectures have significant cost implications. This session
describes a systematic approach to model system availability and
direct specific design choices in order to meet a given high
availability goal.
The communications network used for this case study is a complex
system composed of proprietary and commercial subsystems, leased
services and environmental factors, all of which contribute to
unavailability. In order to make economic yet
quantitatively based design decisions, a method to evaluate the
effects of those
decisions upon availability was needed. Choosing the "best"
components and architecture might not have been sufficient or it
might have been costly overkill. With an extensive network, the
effect of these decisions was simply too difficult to predict.
This presentation discusses a methodology that strikes a balance
between these competing design goals using a logical blend of
reliability and availability prediction techniques, reliability
modeling software, failure budgeting and conservative estimation.
This same approach can be applied to other complex system designs
in order to assure cost-effective availability.
Key Words: Critical
Communications System, Complex Network, High Availability, Design
Guidance
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