A Pre and Post 9-11 Analysis of SS7 Outages in the Public Switched Telephone Network

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Title:	A Pre and Post 9-11 Analysis of SS7 Outages in the Public Switched Telephone Network
Author:	Bajaj, Garima
Description:	The purpose of this thesis is to identify reliability, survivability, and causality differences in Signaling System No. 7 (SS7) outages before and after 9-11. This research addresses questions related to differences in outage frequency, size, duration, blocked calls, impact, time of day, day of week, and causes in pre and post 9-11 outage events. In order to analyze these differences, trend testing, model building, descriptive statistics, mean tests, temporal analysis, and causality analysis were performed. From the analysis it was found that SS7 outage frequency decreased by 60% after 9-11, indicating reliability growth. Survivability is investigated by a variety of impact metrics. A major finding is that the magnitude of impact metrics did not appreciably change. Some significant differences in trigger, direct and root causality were also observed. It was also determined that the direct cause of SS7 network isolation from local and tandem switches was loss of A-links due to human activity, with the root cause being diversity deficits.
Permanent Link:	http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1171294573 http://hdl.handle.net/2374.OX/13630
Date:	2007

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