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Router behavioral complexity (network complexity from a testing perspective). Marco Canini EPFL, Switzerland. Network complexity. Behavior Extensive range of possible behaviors Flexibility of routing software implementations Support for programmability to enhance functionalities
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Router behavioral complexity(network complexity from a testing perspective) Marco CaniniEPFL, Switzerland Marco Canini, RIPE 62
Network complexity • Behavior • Extensive range of possible behaviors • Flexibility of routing software implementations • Support for programmability to enhance functionalities • Highly expressive configuration constructs but low level of network-wide semantic • gives rise to complexity • As in a distributed system, network behavior is aggregate result of interleaved actions of many routers • Heterogeneous and failure-prone environment Marco Canini, RIPE 62
Whole is sum of the parts • Difficult to reason about all possible behaviors • Unanticipated interactions of pieces of software with rather extensive behavior • Subtle differences in inter-operable router implementations • System-wide conflicts under locally admissible decisions • Seemingly valid local fault handling • Different recipes to reach the same network-design objectives • More programmability adds flexibility but extends behavioral complexity Marco Canini, RIPE 62
Code, configuration and inputs drive router behavior Failures Random choices Messages Configuration changes Timeouts Code Inputs Configuration Behavior Marco Canini, RIPE 62
Testing can help to manage complexity • Our vision • Harness the increases in computational power and bandwidth to improve reliability • Our goal • Use online testing to explore system behavior • Make routers aware of the consequences of their actions • Subject the routing system to many possible inputs and let things play out in isolation • Observe the system-wide impact of router actions Marco Canini, RIPE 62
Exploring behavior Explore system behavior Live system Shadow snapshot 1 Shadow snapshot n Space Marco Canini, RIPE 62 Time
Wrap up • Ongoing work • Online testing for BGP • Prototype built into BIRD 1.1.7 • Papers: LADIS ’10, USENIX ATC ’11 • Ultimately • Network itself would be the test platform • Come and see the full talk at the Routing WG session (Wed. at 2pm) Marco Canini, RIPE 62