I would recommend monitoring the data by analyzing the packets on the network as opposed to trying to look at them from one of the servers. You can do this by using the port spanning feature on Catalyst switches and looking at the traffic with an analyzer of some sort. The span feature allows you to mirror the packets from the switch port the server is connected to another port on the switch. (does not affect the real traffic). You then hook up an analyzer tool to the span destination port. There are many tools out there to look at the data with. You basically want to either monitor the utilization between the 2 database server IP addresses or monitor the ammount of traffic on a specific TCP or UDP port number if your database uses a consistant one. This gets you around the problem of just looking at the total port utilization.
A free tool that runs great on linux is called ntop. It provides a nice web page where you can see traffic breakdown for hosts, network, and appliation type. There are also commercial tools like SnifferPro you can load on your laptop to do the same.
You can also use a hardware analyser to do the same thing such a Network Analysis Module if you have Cat 6000 family swich or an external probe like those from Netscout or even a sniffer that provides application monitoring.
Hope this helps!
David Stiff
Manager, Technical Marketing
Enterprise Network Management, Cisco Systems.
