These are some tools that can be used to measure network latency. They were mentioned in (or implied by) Jim Gettys's talk on bufferbloat.
Pingplotter - he says that this is a good tool for figuring out what hop is causing latency, although it is closed-source Windows stuff.
MTR (My Traceroute) is an open-source tool that shows the latency at each hop in a traceroute. It does not produce graphs like Pingplotter, but it does produce good instantaneous data.
ISCI Netalyzer. This is a closed-source java applet-based service. It explicitly checks your network for bufferbloat, as well as other things.
He showed us beautiful latency graphs that were generated by
Queue Management Software
In his talk, he strongly recommended the use of queue management software, such as:
- RED - Random Early Drop.
- AQM - Active Queue Management
- ECN - Explicit Congestion Notification