| the Tempest | a Practical Framework for Network Programmability

|The Tempest framework allows the dynamic introduction and modiication of network services at two levels of granularity. First, the switchlet and associated virtual network concepts enable the safe introduction of alternative control architectures into an operational network. The timescales over which such new control architectures can be introduced might vary from, for example, a video confer-encing speciic control architecture, which is active only for the duration of the conference, to a new version of a general purpose control architecture, which might be active for several months or longer. Second, the Tempest framework allows reenement of services at a ner level of granularity by means of the connection closure concept. In this case modiication of services can be performed at an application speciic level. These attributes of the Tempest framework allows service providers to eeectively become network operators for some well deened partition of the physical network. This enables them to take advantage of the knowledge they possess about how the network resources are to be used, by programming their own specially tailored control architecture. This, as our work with the Tempest shows, is a spur to creativity allowing many of the constraints imposed on operators and end-users to be rethought and for new techniques to be quickly and safely introduced into working networks.