My production servers are kept at US east coast and some of the supporting apps are kept at Amsterdam in Europe. There is a Nagios instance running at US east coast as well which does a few port checks and a few checks via ssh.
Problem is that almost every day I observe packet drops using mtr (combo of traceroute and ping) as well as minor service issues which lasts for about 1 minute. I showed these mtr outputs to our service provider in Amsterdam but he denied any issue saying that ICMP (used by mtr) is not a reliable way to measure the drops since ICMP has lowest priority on the routers. So routers can drop ICMP but they'll be just fine for TCP.
How do I prove this to my service provider that there is indeed an issue with his service and he needs to fix it? What are the right tools and techniques for this?