Mimic Simulation Error when setting topology for Fattree16

[jzzhang8]

Dear Developers,

I have tried to run the code to simulate some fattree networks. But when I tried to simulate for Fattree16, there would always be an error and then the code will exit. (The topology for Fattree16 is in page 12 of https://www.cs.cornell.edu/courses/cs5413/2014fa/lectures/08-fattree.pdf)

The error message for Fattree16 is:

<!> Error in module (IPv4NetworkConfigurator) ApproxFatTree.configurator[0] (id=3) during network initialization: Failed to find address prefix (using 4.1.0.1 with specified bits 255.255.255.255) and netmask (length from 30 bits to 29 bits) for interface ApproxFatTree.core[0].eth1 and 4 other interface(s). Please refine your parameters and try again!.

The parameters in simulate/simulate_mimic_tcp/run.sh is like degree=2, clusters=4, servers=2 which is used for the simulation.

After several trials with other parameters, I found that if I set the servers=2, there would be an error. And if I leave it as the default value (servers=4), the code will be fine.

Would there be any suggestions on why the error happens after setting servers=4? I cannot figure out why such error happens for this simple parameter change. I would really appreciate it if you could help.

Thank you so much!