Ns-2 is the most popular simulator for TCP research. It includes a package called NAM that can visually replay the whole simulation in all timescales. Many Web sites that introduce ns-2 can be found on the Internet. Use NAM to observe a TCP running from a source to its destination, with and without buffer overfl ow at one intermediate router
• Step 1: Search the ns-2 Web site and download a suitable version for your target platform.
• Step 2: Follow the installation instructions to install all the packages.
• Step 3: Build a scenario consisting of three cascaded nodes, one for the Reno TCP source, one for an intermediate gateway, and one for the destination. The links to connect them are full-duplex 1 Mbps.
• Step 4: Configure the gateway to have a large buffer. Run a TCP source toward the destination.
• Step 5: Configure the gateway as to have a small buffer. Run a TCP source towards the destination.
For all the Reno TCP states that the Reno TCP source in the preceding two tests enters, screen dump them and indicate which state the TCP source is in. The figures should be correlated . For example, to represent the slow start behavior you may display it with two figures: (1) an ACK is coming back; (2) the ACK triggers out two new data segments. Carefully organize the figures so that the result of this exercise is no more than one A4 page. Only display necessary information in the screen dumps. Pre-process the figures so that no window decorations (window border, NAM buttons) are displayed.