Failure Analyses of Communications Systems and Networks by Publicly Available Failure Information from the viewpoint of Dependability

Information systems have become indispensable in our daily lives. It is anticipated that if information systems become more huge and complex, more critical failures will occur. However, reports of failures have not been adequately collected. This paper presents failure analyses of communications systems and networks by using public data from newspapers, official governmental information, and news websites in Japan. Our failure data consist of 798 failures that occurred from 2000 to 2013. Of these, 335 failures were significant. Using our database, we analyze and evaluate these failures from the viewpoint of dependability in detail from 2011 to 2013. Our analyses resulted in an error-handling flowchart, classification of failures by the patterns of unsuccessful cases of fault-tolerant functions, and factors leading to error propagation. In addition, countermeasures are identified. We believe that these results will encourage public sharing of failure information.