1 Christophe S. Jelger, Michael Kleis, Burak Simsek, Rolf Stadler, Ralf König, Danny Raz Theories/formal methods in support of autonomic management Dagstuhl Seminar on Autonomic Network management July 2007

2 What is Autonomic Management? Systems that optimize their behavior while evaluating the situation and the re-configuring themselves to be in an optimal working point Systems that optimize their behavior while evaluating the situation and the re-configuring themselves to be in an optimal working point In a system composed of different entities (agents) it is a celebrative decision to assigned roles so that the group will manage and/or optimized itself In a system composed of different entities (agents) it is a celebrative decision to assigned roles so that the group will manage and/or optimized itself There is an underlying target and a measurement technique to estimate the level of success in this goal There is an underlying target and a measurement technique to estimate the level of success in this goal

3 What is autonomic management? Is there always a metric the management task, or is it sometime a 0/1 (managed no managed) problem? Is there always a metric the management task, or is it sometime a 0/1 (managed no managed) problem? Do we always have to have a managed system and a management system with clear boundary? Do we always have to have a managed system and a management system with clear boundary? Some of the answer is related self awareness, but what is the exactly self awareness? What is the difference between a simple control loop and a self awareness system? Some of the answer is related self awareness, but what is the exactly self awareness? What is the difference between a simple control loop and a self awareness system? Where is the boundary between automated and autonomic systems? (and what about autonomous?) Where is the boundary between automated and autonomic systems? (and what about autonomous?)

4 TCP Example TCP – flow/congestion control mechanism Adjust the rate according to current network conditions Work (extremely) well under normal working conditions Without self-awareness Built-in resilience (autonomous) When TCP works over wireless (high loss, over GPRS,..) does not work so well Need to adjust parameters – configure (receiver window, number of Acks,..) For that needs self-awareness For that needs self-awareness

5 TCP Example (2) Inside the enveloped - resilient Outside the enveloped – not resilient Re-configuration

6 The Envelope Model Internal autonomic components –with feedback –no self-awareness System state within the designed working envelope Component self awareness: the observe- detect-react loop –detects if system state is outside the envelope –use reconfiguration to put component inside Why not do all inside the component? –predefined behavior –self-awareness is adaptive Monitor reconfigure detect

7 The Holon Model Each element has internal control loop that deals with a simple problem Several such systems can be combine and more general control mechanism can be used to control the complex system This can be done again and again to create more complex control Makes the use of formal methods practical since they can be applied to small problems Do not need to solve everything at first attempt Monitor reconfigure detect Monitor reconfigure detect

8 Important research challenges Composition and well defines API’s Composition and well defines API’s Theoretical/Formal Models Theoretical/Formal Models – Define the important aspects of of the system and create a formal (well defined model) – Apply formal/theoretical techniques that provide good (provable) results with respect to the model – Construct real system based on the principles developed and check how well they perform in the real world

9 Formal theoretic modeled used Queuing theory Queuing theory – Autonomous load balancing management – Traffic management and admission control Control theory Control theory – TCP – congestion/flow control – Resource allocation and tradeoff management in servers Distributed algorithms Distributed algorithms – Routing and multicast trees – (gossiping) sever migration and load management Complexity theory, state machine, graph theory, Petri Nets, Fuzzy logics, … Complexity theory, state machine, graph theory, Petri Nets, Fuzzy logics, …

10 emerging modeling techniques Bio-Inspired techniques Bio-Inspired techniques – Swarm intelligence – Firefly synchronization – Genetic Algorithms Resource allocation Resource allocation routing routing Network planning (any large multi-dimensional problem) Network planning (any large multi-dimensional problem) – more …

11 Why is formal methods important in particular for autonomic management? To increase reliability of the automatic management system To increase reliability of the automatic management system No human in the system and more management interaction thus more confidence is needed No human in the system and more management interaction thus more confidence is needed Management systems have “a lot of power” and to replace them by an automatic system requires more trust Management systems have “a lot of power” and to replace them by an automatic system requires more trust It is important to distinguish between the same phenomenon that looks like 2 different ones It is important to distinguish between the same phenomenon that looks like 2 different ones Gives an inherent understanding of the domain that can be used to derive good protocol that works under different conditions Gives an inherent understanding of the domain that can be used to derive good protocol that works under different conditions Give predictability in general but simulation is good only in the domain that was measured Give predictability in general but simulation is good only in the domain that was measured

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13 Challenges How much management How much management – Too little – not good – Too much – takes resources from system Separate management processes Separate management processes – makes things simpler – cannot be optimal - uses only the API