10 Killer Open Source Networking Tools
#4 My TraceRoute
MTR is a great tool for troubleshooting network links that traverse multiple routers. Specify a destination, and MTR shows you a list of routers that your traffic passes through on the way (as well as the destination itself) and the results of a continuous ping to those routers.
MTR updates the statistics of the pings as it runs, so you can see which routers are slow to respond or which are dropping a significant number of ping requests. The results include the percentage of lost packets, the response times from each router (average, best, and worst), and the standard deviations for those times.
In the matter of internet slow down, which could be because of specific website or because of ISP, MTR is a great way to see whether there really is a problem and to get a quick idea of where the problem resides.