Introduction to NetSpec

NetSpec is a network level end-to-end performance evaluation tool developed by researchers in the University of Kansas, to help in the collection of results delivered by performance experiments on the ACTS ATM Internetwork (AAI) project. The NetSpec system provides support for large scale data communication network performance tests with a variety of traffic source types and modes. This software tool provides a simple block structured language for specifying experimental parameters and support for controlling performance experiments containing an arbitrary number of connections across a LAN or WAN.

NetSpec exhibits many features that are not supported by the most often performance tools used today (ttcp, Netperf), like parallel and serial multiple connections, a range of emulated traffic types (FTP, HTTP, MPEG, e.t.c.) on the higher levels, the most widely transport protocols used today, that is TCP and UDP, 3 different traffic modes, scalability, and the ability to collect system level information from the communicating systems as well as intermediate network nodes.

Netspec Architecture

Figure 1 shows the basic NetSpec 3.0 architecture. The controller is a process that supports the user interface, which is currently a file containing a description of an experiment using a simple block structured language in which the connection is the basic unit for an experiment and via the control daemon controls the daemons implementing the test. For every connection in the experiment, the corresponding test daemons are created. These test daemons concentrate on performing the traffic related tasks (send or receive data transferred across the connection). Each daemon is responsible for its own report generation after experiment execution is complete and measurement daemons concentrate on collecting data as accurately as possible, without having to worry about performing traffic functions. The output report is delivered to the controller via the control daemon for viewing by the user. The communication between the controller and the daemons is achieved using an ASCII based language, which enhances portability and extensibility.

Figure 1: NetSpec 3.0 Architecture

Traffic Modes

NetSpec supports three basic traffic modes:

Emulated traffic Modes

Netspec has the potential to emulate FTP, TELNET, VBR Video Traffic (MPEG, Video-Teleconferencing), CBR Voice Traffic, and HTTP traffic (World Wide Web traffic) on the application layer. This feature makes Netspec one of the unique Network Performance Evaluation Tools supporting such kind of traffic types and comes out to be an essential tool for the Network Engineer, being able to test the network's performance under different emulated traffic types.

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