Using NDIS intermediate drivers for extending the protocol stack. A case study

Internet protocols continuously evolve through the development of new protocols and new extensions being added to the existing protocols, as a result of the increasing demands on information transfer. Consequently, operating systems need to embed periodically the new low-level protocols and protocol extensions. Since this is not always possible, especially when proprietary operating systems are involved, the means for extending the protocol stack with kernel extensions implementing support for the new added services should be provided by the operating systems' owners. This is exactly what the authors aim to demonstrate within this paper with the IP mobility support (Mobile IP), a newly defined service, and Windows NT version 4, a proprietary operating system that does not natively implement this service. The paper addresses the architecture trade-off of a suitable protocol stack, platform configuration, and resource reusing. The case is made for an intermediate driver approach, and the paper addresses packet flow control and packet management based on reusing the Tcpip.sys provided services. The parameters affecting the architecture and processing related performance of the extended protocol stack are identified and performance data are provided. All the assertions below are based on the prototype developed by the authors.