Backbone Monitoring Tools

Hi All, I want a simple backbone monitor for my 5 datacenters. My "backbone" consists of redundant IPSEC/GRE tunnnels. At the very least I want to ping, traceroute and transfer a small file every few minutes over all IPSEC links. I am sure there are products that do this already, but I am having a hard time finding any. The display format should be noc-friendly. A basic grid with green/red status indicators at the least. Geographical maps a plus. Do most of you use a home grown tool for this monitoring and alerting ? Regards, Ashe