How do I configure NetSim to run an emulation in one VM and use this to test network performance? The other VMs running applications will need to send their application data 'through' the virtual network in NetSim.
Yes NetSim can be configured to run per your requirements.
The lab setup would be as follows
1. A physical server will be running vSphere with multiple VMs
2. A dedicated physical system running NetSim (Win 8 / Win 10 OS)
3. Network connectivity between the vSphere server and NetSim system through a switch
4. Set the gateway in the vSphere VMs to the NetSim Emulator system
5. Create a 'virtual network' in NetSim. Map real devices to virtual devices inside NetSim.
6. Run your applications. Traffic will now 'flow through' NetSim and encounter network effects such as delay, loss, error depending on the virtual network created, NetSim will then output network performance metrics which can be analyzed.