I have a somewhat small network with a 100MB link. I have about 175 workstations and I want to monitor bandwidth usage. I have a 1GB tap in place between my router and the outside world. I tried Colasoft nChronos and it does exactly what I need too but the price is just way to much. I am looking for some open source solution that can monitor all traffic with a graph and log it to a DB. When a large spike in traffic is seen I want to be able to dig down and see who or what in my network is causing it. Are there any solutions like that and not a nightmare to deploy? Even a small cost may be worth it.