Experiences with NIMI

NIMI (National Internet Measurement Infrastructure) is a software system for building network measurement infrastructures. Its design emphasizes: (i) large-scale infrastructures composed from diversely-administered hosts, rather than infrastructures controlled by a single entity, and (ii) facilitating diverse types of measurements by diverse parties, some of whom are allowed richer access to certain portions of the infrastructure than others. We discuss our experiences with developing and operating the infrastructure to date: problems we have encountered, both foreseen and unanticipated, mistakes we made, and how we have adapted the design to address these. We also explore two key issues for developing a large-scale, extensible infrastructure: the problem of securely updating software on the measurement platforms, and the problem of constraining the resources consumed by different measurements. We argue that both of these can be unified in terms of controlling the behavior of the measurement software. But we also argue that, due to the varying burdens and benefits of the different mechanisms for providing this control, NIMI will need to provide "gradations" of security for different sites to choose from as best fits their requirements and resources.