Ask HN: What do you use to test latency, jitter, etc. between servers?

What do people use to test various metrics between servers? (bare-metal or not). I'd imagine metrics like the following would be very useful: - latency - packet loss - jitter - Bandwidth - All of the above, but with different QoS settings. The data should then be able to be displayed as a checkered dashboard which gets green/yellow/red based on the various metrics.