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Trends in Local Telecommunication Switch Resiliency

Authors:
Andrew Snow
Gary Weckman

Keywords: reliability growth; resiliency, outage index; homogeneous poisson process (HPP), non-homogeneous poisson process (NHPP), Laplace trend test, time series of events, fault management

Abstract:
This paper presents a time series analysis of outage causality trends for local telecommunication switches in the United States. Additionally, the resiliency of local switches is assessed by examining changes in severity of outages over time by causality. Almost 13,000 Public Switched Telephone Network (PSTN) switch outages are examined over a 14-year period. Causality trends were examined from both resiliency and reliability perspectives, for scheduled outages, and failure induced cause categories such as procedural errors, design errors, random hardware failures, and external events. Examples of reliability growth, constancy, and deterioration are noted among these casual categories. Likewise, examples of increasing, constant and decreasing impact trends are also noted. To examine resiliency, a novel severity index metric is introduced that is not only intuitive, but also robust, given the long tailed distribution of outage impact. The new index allows time series comparison between causality reliability and outage impact trends. Interestingly, in some instances causality reliability trends were different from the corresponding impact trends. For example, when all outage causes are combined, a reliability growth trend is indicated while outage impact is constant. To get a good perspective on resiliency, both reliability and outage impact trends must be examined. Trends are assessed both graphically and analytically, and conclusions are reached with strong statistical inference.

Pages: 178 to 184

Copyright: Copyright (c) IARIA, 2014

Publication date: February 23, 2014

Published in: conference

ISSN: 2308-4413

ISBN: 978-1-61208-318-6

Location: Nice, France

Dates: from February 23, 2014 to February 27, 2014