We have ten servers in two groups servers, and there is a lot of traffic between those groups - too much we think. We know this because of stats of our provider, but don't know how this traffic is built up, and which servers cause this. There is no cluster or failover or anything - each server stands on its own.
I would like to know which server(s) causes this traffic, but don't know how I can monitor this. What program or service can do this? Preferably it could monitor all local network traffic, in 10.x.x.x ip range.