Understanding TCP/IP Model Internals and Interfaces
Understanding TCP/IP Model Internals and Interfaces
Understanding TCP/IP Model Internals and Interfaces
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1508 <strong>Underst<strong>and</strong>ing</strong> <strong>TCP</strong>/<strong>IP</strong> <strong>Model</strong> <strong>Internals</strong> <strong>and</strong> <strong>Interfaces</strong><br />
4. How many segments were retransmitted? ___________<br />
5. Were any segments retransmitted unnecessarily? ___________<br />
6. When is the last segment sent? ___________<br />
Detailed Analysis (Homework)<br />
Similar to the flavors we have already examined, <strong>TCP</strong> SACK retransmits segment 23 using the fast<br />
retransmit algorithm. However, it uses a different approach to determine when <strong>and</strong> which packets are<br />
sent out during fast recovery. It calculates the amount of in-flight data based on selective<br />
acknowledgements that it has received. Data can be sent only if the amount of outst<strong>and</strong>ing data is<br />
lower than the size of the congestion window. Because it has information about which segments<br />
were received, it is able to resend only missing segments <strong>and</strong> then continue with transmission of<br />
unsent data.<br />
Run Simulation for <strong>TCP</strong> Tahoe, <strong>TCP</strong> New Reno <strong>and</strong> <strong>TCP</strong> Reno with ECN Support<br />
1. Select Scenarios -> Manage Scenario.<br />
2. Set “Results” to “collect” for Tahoe, new Reno <strong>and</strong> ECN scenarios.<br />
3. Click OK to run the simulations.<br />
4. Click Close after simulation completes.<br />
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