Network Monitor is a network diagnostic tool that monitors local area networks and provides a graphical display of network statistics. Network administrators can use these statistics to perform routine trouble-shooting tasks, such as locating a server that is down, or that is receiving a disproportionate number of work requests. Note that unless you are familiar with network protocols, you will need to read the extensive online documentation before using this program.
While collecting information from the network's data stream, Network Monitor displays the source address of the computer that sent a frame onto the network, the destination address of the computer that received it, the protocols used to send the frame and the data, or a portion of the message being sent. If you need to get deep down into the behaviour of your network, then this range of statistics should be more than enough although obviously you'll need to know how to interpret them. Note that to use Network Monitor, your computer must have a network card that supports "promiscuous mode". A great tool for those that need highly complex information about their network.