Viewing/Interacting with the simulation

Once the simulator is configured, the simulator is ready to be started. The following provides a brief description on how different parts of the Graphical User Interface (GUI) can be used during the simulation. For a complete guide, please refer to Section 4.3 for Appendix 3 in the thesis.

The main GUI looks like the following -

TCP Simulator GUI Screenshot

The different parts of the GUI are described below.

Send Window Panel Visualizes the TCP send window for the Left and Right hosts.

Info. Panel Displays state/action information as well as statistics for the data transfer process undertaken by the TCP of each host.

Stream Panel Displays TCP segments traveling between hosts.

Tab Panel Holds controls and information for each host's TCP.

Central Command Panel Holds simulator controls commonly accessed by the user.

Before starting the simulation, each host's TCP should be issued commands. This is accomplished by pressing the "Issue Command" button in the Command Tab for each host's Tab Panel to bring up its Issue Command Panel. The "Start" button in the Central Command Panel is then pressed to begin the simulation.

As the simulator runs, users can -

View the delay and loss conditions experienced by segments traveling between hosts by looking at the Stream Panel or the Delay/Loss or Avg. Delay/Loss tabs for each host's Tab Panel.

View the operations each host's TCP undertakes to respond to these conditions by looking at
- How each TCP regulates its data send rate via its Send Window Panel
- The status of each host's TCP as displayed in each host's Info. Panel.
- Each host's TCP components (TCP Timers etc) as displayed in each host's Tab Panel.

View the outcome of these operations by looking at the statistics for the data transfer process undertaken by each host as displayed in each host's Info. Panel.

Interact with the simulation by -
- Issuing new commands to each host by pressing the "Issue Command" button in the Command Tab in each host's Tab Panel to bring up its Issue Command Panel.
- Changing the Base Tahoe variables/parameters above used by the TCP of each host.
- Changing the custom flow control variables used by the TCP of each host by accessing the Variables Tab for each host's Tab Panel.
- Changing the delay/loss experienced by segments traveling Left to Right or vice versa by pressing the "Edit Delay" or "Edit Loss" button as shown in the Delay/Loss or Avg. Delay/Loss tabs.

Note that most of the simulation controls are only available if the simulation is paused (See Central Command Panel).

By viewing/interacting with what is occurring in the simulator, the dynamics of simulated flow control algorithms are clearly shown to the user.