Nam is a Tcl/Tk based animation tool for viewing network simulation traces and real world packet traces. It supports topology layout, packet level animation, and various data inspection tools.
The network animator ``nam'' began in 1990 as a simple tool for animating packet trace data. This trace data is typically derived as output from a network simulator like ns or from real network measurements, e.g., using tcpdump.
Available at: http://www.isi.edu/nsnam/nam/