NetSim Support Portal

As the number of devices in a network increases, the computational requirements of NetSim increase steeply. Therefore we recommend you to follow the guidelines given below:

1. Running simulations with high capacity systems (the higher the better):
   RAM: 16 GB or higher. Preferably 32 GB 
   Processor:  i7 equivalent or above, preferably Xeon 
   OS - Win 10 64 Bit. Hard Drive: SSD
2. Please also see - https://support.tetcos.com/en/support/solutions/articles/14000102436-what-are-the-system-requirements-to-run-largest-simulation-in-each-netsim-version-
3. Turn Off Animation by selecting the "Don't Play/Record Animation" option.
   
4. Disable logs: 
   • Turn Off Trace files such as Packet trace and Event trace. 
     • As the simulation scenarios get larger or as you run simulations for longer times, the log file gets larger and larger (100s of MBs and then into GBs) and the simulation will slow down. 
   • Turn Off Plots
   • Win OS and C / C ++ run time libraries have a limit of max 255 open files per session. Ensure the number of files being written is less than this
5. Start with a small network with a lesser number of devices and ramp up slowly (Eg: start with 50 nodes and ramp up in steps of 25 / 50)
   • Create a scenario with fewer devices, simulate it, and save the scenario. Then open the saved scenario and add more devices to it. After simulating the scenario by adding more devices, you can go to File> Save-as option to save this scenario as a new experiment. You will then have 2 experiments one with lesser devices and one with more devices. 
   • In this way, you can keep adding more devices/applications and also maintain a copy of the experiment during each iteration for analysis.
6. Start with a short simulation duration and ramp up slowly (Eg: start with the 50s and then ramp up to 500 s in steps of 25 / 50 s).
   • Having a scenario with a large number of routers is an exception since convergence time may be high. If there are a large number of routers then run the simulation for a longer duration. 
7. Run applications over UDP protocol first. And then add TCP after confirmation of expected working.
   • In the case of scenarios with a large number of routers, attempts of TCP connection establishment may fail since the TCP_SYN generated at the source node is not routed at the simulation start before routes converge. Hence set the application start time as 10s or 20s.
8. The application generation rates should be less than the bottleneck capacity. If not packet build-up will occur and simulation will necessarily slow down because more and more data is being written-to/read-from memory. Keep the generation rate low by setting high packet inter-arrival times, else ensure there is sufficient network capacity. 

Related articles:

https://support.tetcos.com/en/support/solutions/articles/14000057035-what-is-simulation-time-

https://support.tetcos.com/en/support/solutions/articles/14000073337-how-can-i-scale-my-network-and-test-app-performance-