24 decentralized control planetlab is a world wide

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2.4 Decentralized Control PlanetLab is a world-wide platform constructed from components owned by many autonomous organizations. Each organization must retain some amount of control over how their resources are used, and PlanetLab as a whole must give countries and geographic regions as much autonomy as possible in defining and managing the system. As a consequence, PlanetLab must support decentralized control , which in turn requires minimizing the aspects of the system that require global agreement. Doing so allows autonomous organizations to federate in the formation of a global facility and for these organizations to define peering relationships with each other. 2.5 Efficient Resource Sharing While a commercial variant of PlanetLab might have sufficient resources (and cost recovery mechanisms) to ensure that each slice can be guaranteed all the resources it needs, PlanetLab must operate in an under-provisioned environment. This means conservative allocation strategies are problematic, and it is necessary to promote efficient resource sharing. Guarantees should be possible, but the system must also support “best effort” slices and a flexible way for slices to acquire needed resources. In this context, PlanetLab adopts adopts a two-pronged resource allocation strategy. First, it decouples slice creation and resource allocation. This means all slices are given only best effort promises when they are first created. They then acquire and release resources over time, assisted by available brokerage services . It is not the case that a slice is bound to a guaranteed set of resources during its entire lifetime. Second, even though some slices can acquire guaranteed resources for a period of time, we expect overbooking to be the norm. PlanetLab must provide mechanisms that recover from thrashing due to heavy resource utilization. 3 Principals and Trust Relationships The PlanetLab architecture recognizes three main principals: An owner is an organization that hosts (owns) one or more PlanetLab nodes. Each owner retains ultimate control over their own nodes, but delegates re- sponsibility for managing those nodes to the trusted PLC intermediary. PLC 5
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provides mechanisms that allow owners to define resource allocation policies on their nodes. A user is a researcher that deploys a service on a set of PlanetLab nodes. PlanetLab users are currently limited to individuals employed by research organizations (e.g., universities, non-profits, and corporate research labs), but this is not an architectural requirement. Users create slices on PlanetLab nodes via mechanisms provided by the trusted PLC intermediary. The PlanetLab Consortium (PLC) is a trusted intermediary that manages nodes on behalf a set of owners, and creates slices on those nodes on behalf of a set of users.
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  • Spring '10
  • CS
  • IP address, slice, Slice Authority

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