Home: Grasp

Understanding and validating the timing behavior of real-time systems is not trivial. Many real-time operating systems and their development environments do not provide tracing support, and provide only limited visualization, measurements and analysis tools.

Grasp is a tool for tracing, visualizing and measuring the behavior of real-time systems. It provides a simple plugin infrastructure for extending Grasp with custom visualization and measurement methods.

It supports the visualization of:

• partitioned and global multiprocessor scheduling,
• migrating tasks and jobs
• communication between jobs via shared memory and message passing,
• hierarchical scheduling on uni- and multiprocessor systems

Grasp is available on Windows, Mac, Linux, and as a TclKit.

Home: TcpViz

TcpViz is an interactive visualization tool demonstrating the differences between three flavours of the TCP protocol: Tahoe, Reno and New Reno. It was developed as a teaching aid and has been used in various graduate courses on computer networks.

It allows to set several parameters, such as the Round Trip Time (RTT) or propagation delay, and to select which packets should be dropped by the network.

It shows different views of the TCP protocol from the perspective of the sender, including

• the outgoing buffer together with the sliding congestion window (CWND)
• a plot of the CWND size and threshold (SSTHRES) against time and against round-trip time (RTT)
• a plot of sent DATA segments and received acknowledgement (ACK) segments against time
• a sequence diagram describing occurring events (e.g. arrival of an ACK segment or a timeout) and the corresponding actions

TcpViz is available on Windows, Mac, and as a TclKit.