Using windows/dos ping to test qos
IP-SLA is a much better solution, but for a quick test you can use ping
with the -v option to set the DCSP or TOS of the packets. This
might allow you to show that ping responses are different for different
classes of traffic over a congested network.
The one catch is
that it isn't obvious what value to use for the -v option - some
trial and error with Wireshark tells me that -v 185 will give DCSP of
EF, but the mapping is slightly different to what I had expected).