kusanagi is a collection of tools intended for trouble shooting including ones for system behavior analysis(e.g., oprofile log analyzer) and utilities(lkms) to catch specific (in-kernel) events etc.
PNETPROBE is a series of Perl scripts to catch and manage tcpdump data. It uses MySQL to dump data, and uses GD::Graph for all plotting functions. This tool will be ideal to see what is flowing in how many quantities on your network.