NetVizura NetFlow Analyzer - NetFlow Analyzer is a solution for bandwidth monitoring and traffic analysis. It helps with traffic investigation, analysis and reporting
RRDTool - High performance data logging and graphing system for time series data
Abusix - Abusix is a network security company that offers email threat protection and network abuse handling solutions to ISPs, Telcos, and Cloud/Hosting Providers to stop the rapidly growing problem of email-borne threats and other kinds of network abuse.
MRTG - MRTG (or Multi Router Traffic Grapher) is an open-source network monitoring tool.
Easy-IP - IPAM and DNS for Telecoms
Ganglia - Scalable distributed monitoring system