I would say that you should get a copy of Network Maintenance and Troubleshooting Guide: Field Tested Solutions for Everyday Problems, 2nd Edition by Neal Allen and get a couple of switches, setup HAProxy and couple of routers and get to work. You should be able to simulate the traffic virtually but the know how of the physical is always important too. Plus look into VMs like the Cisco UCS vm for looking at fiber switching and F5 BigIP vm for load balancing a bit vendor specific but free...