Heidemann Spring 2002 HW3 Q3

3: You have graduated and Andersen Consulting has hired you for a Highly Paid Consulting Engineer job. Their first job for you, should you accept it, is to help a client of theirs with a TCP performance problem. Their customer, Non Such Agencé, won't let you examine their application directly (for some unspecified reason), but instead has given you a simulation that they guarantee faithfully reproduces it. You may obtain these simulations, called ``test_a.tcl'' and ``test_b.tcl''

They say the application involves sending a 200,000 byte file via TCP between two nodes ``left'' and ``right''. You need to identify the primary limit on TCP performance for each scenario. You may do this by examining the simulation scripts or running the simulations and analyzing or animating the raw output traces or the nam output traces.

a) What is the primary performance bottleneck of test_a.tcl and what is the least expensive way to fix the problem?

b) What is the primary performance bottleneck of test_b.tcl and what is the least expensive way to fix the problem?

Problem Hints: the answers should be different. Consider the bandwidth and delays of the links and how they interact. Short answers are OK as long as you clearly identify the problem.

Nam hint: hit the ``re-layout'' button when nam starts up to get a better layout.