Hello Serverfault !

I have a big distributed system I need to monitor.

Background:

My system is comprised of two servers, concentrating and controlling the system. Each server is connected to a set of devices (some custom kind of RF controllers, doesnt matter to my question), each device connects to a network switch, and eventually all devices talk to the servers, the protocol between the servers and the devices is UDP, usually the packets are very small, but there are really a LOT of packets. the network is also somewhat complex, and is deployed on a large area physically. i'll have 150-300 of these devices, each generating up to 100+ packets per second, and several network switches, perhaps on 2 different subnets.

Question

I'm looking for some solution that will allow me to monitor all this mess, how many packets are sent, where, how do they move through the network, bandwidth utilization, throughput, stuff like that. what would you recommend to achieve this?

BTW Playing nice with windows is a requirement.