In production the question comes up regularly: how many megabits
actually pass between two points. iperf3 is the standard tool for
measuring TCP/UDP throughput in both directions.
In this lesson you start an iperf3 server on one node, a client on the
other, and measure baseline throughput. Then you degrade the network
with tc netem (latency + loss) and compare. The basic effect, the
bandwidth-delay product in TCP: under loss the tcp-handshake opens
normally, but the congestion window cannot ramp back up in time (details
on the states are in tcp-states).