Dynamic network reconfiguration support for mobile computers

Hot swapping technology combined with pervasive heterogeneous networks empowers mobile laptop users to select the best network device for their current environment. Unfortunately, the majority of system software remains “customized”for a particular network configuration, and assumes that many characteristics associated with the network environment remain invariant over the runtime of the software. Mobility causes changes in the environment and nullifies many of these assumptions. This leads to severe loss in system functionality when resources are lost, and failure to benefit when resources are gained. This paper describes Physical Media Independence (PMI), an architecture for dynamically diverse network interface management. PMI addresses three issues concerning dynamic network configuration. First, a model for device availability is proposed to accurately determine when a network device is operational. Second, a structured methodology is used to construct adapters that reconfigure the system when the set of available devices change. The methodology breaks traditional layering using a meta-interface to pass events and information among layers, allowing each layer to adapt in a manner best suited to it. Third, we examine the effect of transparent and non-transparent reconfiguration operations on a variety of applications. We find that adaptive, resource intensive applications behave more efficiently when informed of device availability events. We compare the functionality of an adaptive application running on top of a adaptive operating system (OS) with and without cross-layer notifications.