1. Catastrophic Failures in Networked Systems Jon Crowcroft Jon.crowcroft@cl.cam.ac.uk http://www.cl.cam.ac.uk/~jac22/out/bcs.pdf

2. Non Complex Failures Naming Routing Searching

3. Complex & Emergent Phenomena Sunchronisation of Routing Updates Self Similar Traffic Scale Free Topology Non Emergent Properties Phase Changes Congestion collapse

4. Complex Badness Malware Unintended End system attack side effect overloads control plane => No routes Self limiting Intentended Zero Day work spread Vigilante defense spread Race!!! Outcome - depends on lots of parameters And initial conditions - just like H1N1 :-)

5. Conclusions We have had several near misses mostly features of complicatedness Not really complexity Doesn’t mean we don’t have things to fix mainly just be better engineering