Complex Systems Workshop, September 20-21, 2012

Evaluation of Complex SystemsJ. Bryan Lyles

Program DirectorCISE/CNS

Credit: MONET Group at UIUC

Society IssuesWe increasingly rely on the Internet but are unsure we

can trust its security, privacy or resilience

Science IssuesWe cannot currently

understand or predict the behavior of complex,large-scale networks

Innovation IssuesSubstantial barriers to

at-scale experimentation with new architectures, services, and

technologies

Global networks are creatingextremely important new challenges

Revolutionary GENI IdeaSlices and Deep Programmability

Install the software I want throughout my network slice(into firewalls, routers, clouds, …)

And keep my slice isolated from your slice,so we don’t interfere with each other

We can run many different “networking experiments” in parallel

GENI and Complex Systems

• Scale• Configurability, including configuration re-use• Repeatability• Tools supporting experimentation

GENI ≤ Problem Solution2

Research Methodology

What is “strange” about this graph?

Levin, et al, Sigcomm 2008

The Other (more than) Half

• How do you plan an experiment?• The framing of hypotheses• Integration of a priori knowledge• Identification of the components that matter• Identification of parameter values to be tested• Required measurements and instrumentation• Experimentation plans that are complete but feasible

• Interpretation of results• Significance & reliability

• What can we learn about moving beyond testing?• Designing for “controlled failure”• How do we design systems that are easy to characterize?

At the End of the Day

Starting with a hypothesis about a complex system, I want an outside observer to have confidence that I have considered the alternatives, checked the boundary cases and fully understood system behavior.

Where are our biggest gaps in being able to do this?