Diversity Diversity Michele Morganti 2 nd ReSIST Open Workshop 18 - PDF document

Resilience in Computing Systems and Information Infrastructures: A Research Agenda Diversity Diversity Michele Morganti 2 nd ReSIST Open Workshop –18 October 2007 – Rome, Italy About D13 Diversity at large Deliverable D13 - From Resilience-Building to Resilience- Scaling Technologies: Directions on Diversity ! Good analysis and assessment ! Valuable conclusions and directions for future research ! Following comments/observations intended solely as contributions to reasoning/discussion ! No implicit or explicit criticism 10/22/2007 2

Unforeseen events vs. Unavoidable changes D13 Adverse events • extreme, catastrophic Robustness • rare, unlikely • correlated, insider Diversity • . . . Continuous evolution • context Adaptability • technology • size • . . . Where did complexity end up ? 10/22/2007 3 Security vs. Survival Gold Gold Pot Pot Gold Gold Pot Pot Cup Cup Gold Gold Gold Gold Cup Cup Hostile attacker Malicious attacker • enemy • thief • terrorist • spy • vandal • . . . • . . . Mike’s paradox: “Whatever the choice, Resilience is in the other” 10/22/2007 4

Diversity vs. Redundancy Fault-Tolerance vs. Performance, Coverage, … Fault Fault Continuity Survival with some Degradation without Degradation High Low Performance / Performance / Low Resilience High Resilience Structural vs. Infrastructural In-built vs. Outsourced Systems vs. Services Redundancy vs. Multiplicity 10/22/2007 In-built systems vs. Outsourced services Public Networks Private and Ad-hoc Networks 2G NGN 3G W-LAN Operator A BWA Service to Public Networks Provide X GSM-R 2G MN Operator B TETRA 3G Service Provide Y Ad-Hoc BWA FN Operator C Hot- -Spot Same basic functions but totally different characteristics 10/22/2007 6

Space vs. Time related Diversity D13 Space related Interoperability • replication (horizontal & vertical) • segmentation • . . . Diversity Time related Compatibility • expansion (backward & forward) • evolution • . . . A different focus/role for standards ? 10/22/2007 7 Architectures with explicit redundancy Suggested fully redundant GSM-R architecture (Fully duplicated network structure with overlayed radio cells) BTS BTS AC HLR VLR BTS OMC MSC BSC BTS BTS OMC MSC BSC BTS BTS AC HLR VLR BTS Can we quantify diversity pro/con tradeoffs ? 10/22/2007 8

Architectures without explicit redundancy AC EIR GSM/GPRS Reference Architecture NMC HLR OMC BTS VLR MSC BSC MSC MS BSC PSTN SIM SGSN GGSN PDN Time related diversity is unavoidable in complex, long lasting systems 10/22/2007 9