We have an international line between two sites with limited bandwidth. I want to monitor bandwidth usage between the two sites, and understand which type of traffic consumes the most.
Ideally I would like to have a "per-second" breakdown of the amount of data arriving at the "end" site per TCP & UDP port - this way I could see which of our application is using the most. I don't really need a nice graph, a simple text file would be enough.
I have access to the Cisco 2960 connected to the link's router (but not to the router itself), managing to extract data from the switch would be ideal as it's the single point of entry.
Another option would be to do the same thing on each of the linux server that is sending data through the link.
I haven't managed to find a tool that would help me with that - there are plenty of things around (netstat, iftop), but they don't seem to be able to spit out a "per port" split every second...
Can anybody think of a (lightweight) specific tool & method to achieve this ?
Edit: I already use MRTG to get a rough idea of the amount of traffic on the link, but it's not precise enough. It's probing the link every 5 minutes (not every second), and it's not making any distinction between TCP/UDP ports.