Nomenclature and Data SourcesHistory and Political Economy of PSTNThe period of monopoly (until 1984)The breakup of the monopoly (after 1984)Summary of constraints and the current state of PSTNNetwork AnalysisNetwork Modeling Decisions and AssumptionsCall scenarios and the networks to analyzeNetwork Experiments: Dynamically changing Pearson’s CorrelatCase 1: Randomly add edges within each cluster of Central OfCase 2: Randomly add edges between all Central OfficesCase 3: Completely randomly add edges to the Mini Bell netwoSummary of Pearson’s degree correlation experimentsNetwork Experiments: Robustness Analysis for Nano BellCase 1: Randomly remove nodesCase 2: Randomly remove edgesContributions to the ESD.342 Project PortfolioRecommendations for Future WorkReferencesPublic Switched Telephone Networks: A Network Analysis of Emerging Networks Daniel Livengood, Jijun Lin and Chintan Vaishnav Engineering Systems Division Massachusetts Institute of Technology Submitted May 16, 2006 To Dan Whitney, Joel Moses and Chris Magee Page 1Table of Contents Nomenclature and Data Sources..................................................................................... 4 History and Political Economy of PSTN.........................................................................................5 The period of monopoly (until 1984).............................................................................. 5 The breakup of the monopoly (after 1984) ..................................................................... 8 Summary of constraints and the current state of PSTN ..............................................................10 Network Analysis...............................................................................................................................12 Network Modeling Decisions and Assumptions........................................................... 12 Call scenarios and the networks to analyze .................................................................. 12 Network Experiments: Dynamically changing Pearson’s Correlation Coefficient ..................17 Case 1: Randomly add edges within each cluster of Central Offices (COs) ................ 17 Case 2: Randomly add edges between all Central Offices ........................................... 18 Case 3: Completely randomly add edges to the Mini Bell network ............................. 21 Summary of Pearson’s degree correlation experiments................................................ 22 Network Experiments: Robustness Analysis for Nano Bell........................................................23 Case 1: Randomly remove nodes.................................................................................. 23 Case 2: Randomly remove edges.................................................................................. 24 Contributions to the ESD.342 Project Portfolio ..........................................................................26 Recommendations for Future Work...............................................................................................26 References ...........................................................................................................................................27 List of Tables Table 1: Call scenarios represented by phone company interactions.........................................12 Table 2: Network analysis metrics for the five networks modeled.............................................16 Table 3 Summary of Pearson's degree correlation experiments .................................................22 Table 4 Number of node failures that Nano 2005 and 2010 can tolerate (500 runs)..............23 Table 5 Number of clusters existing in the rest of the network with random node failures (50 runs) .....................................................................................................................................................23 Table 6 Number of edge failures that Nano 2005 and 2010 can tolerate (500 runs)...............24 Table 7 Number of clusters existing in the rest of the network with random edge failures (50 runs) .....................................................................................................................................................24 Page 2List of Figures Figure 1 PSTN connectivity in 1928.................................................................................................6 Figure 2 (a) AT&T’s five-level hierarchy in 1970s (b) AT&T’s regional network with five-level hierarchy.......................................................................................................................................7 Figure 3 Level-skipping in pre-1975 networks ................................................................................8 Figure 4 Regional Bell Operating Companies: then and now .......................................................9 Figure 5 (a) Dynamic non-hierarchical routing (DNHR) and (b) the new hierarchy ..............10 Figure 6 Nano Bell Networks: Current (2005) and Future (2010) .............................................13 Figure 7 Robustness in redundant fiber rings................................................................................14 Figure 8 Current Mini Bell network ................................................................................................15 Figure 9 Nano and Mini Bell networks connected .......................................................................16 Figure 10 Randomly add edges within central offices' clusters...................................................18 Figure 11 Mini Bell network when r=0 ..........................................................................................18 Figure 12 Randomly add edges for all central offices...................................................................19 Figure 13 Mini Bell when r = 0 with 190 added edges.................................................................19 Figure 14 Mini Bell (a) when r = 0 with 1599 added edges and (b) when r = 0 with 2305 added edges.........................................................................................................................................20 Figure 15 Randomly add edges for all central offices and tandems ...........................................21 Figure 16 Mini Bell (a) when r = 0 with 306 edges and (b) when r = 0.1574 (near peak) with 1121