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NIST Network Emulation Tool (NIST Net) NIST Net is a general-purpose tool for emulating performance dynamics
in IP networks. The tool was designed to allow controlled, reproducible experiments with network performance sensitive applications and control protocols in a simple laboratory setting. By operating at
the IP level, NIST Net can emulate the critical end-to-end performance characteristics imposed by various wide area network situations (e.g., congestion loss) or by various underlying subnetwork technologies (e.g.,
asymmetric bandwidth situations of xDSL and cable modems). NIST Net is implemented as kernel modules and extensions to the Linux operating system and
an X-windows based user interface application. In use, the tool allows an inexpensive PC-based router to emulate numerous complex performance scenarios, including: packet loss distributions, congestion loss,
bandwidth limitations, and packet reordering / duplication. The X-windows interface allows the user to select specific traffic streams passing through the router and to apply selected performance
"effects" to the IP packets of the stream. In addition to the interactive interface, NIST Net can be driven by traces produced from measurements of actual network conditions. NIST Net also provides support
for user defined packet handlers to be added to the system. Examples of the use of such packet handlers include: time stamping / data collection, interception and diversion of selected flows, generation of
protocol responses from emulated clients.For more information on the NIST Net project, or to download the tool see:
http://www.antd.nist.gov/itg/nistnet/
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