open your terminal/command line:

# while true ; do COMMAND ; sleep 1 ; done # executes COMMAND every second
while true ; do ll ; sleep 1 ; done # show me content of current dir, every second (cool for monitoring changes to that dir)

# on server and client install iperf
apt-get update
apt-get install iperf
# on server machine
iperf -s
# on client machine, where is ip of server
while true ; do iperf -c -r ; sleep 1 ; done # run bandwidth test of server<-switch1-switch2->client, pause for a second then repeat