Control the traffic of each packet between elastic block store volume and elastic computing cloud to find high leverage of performance transaction processing between 2 level volumes.
If you want to just monitor traffic, I think you can use monitoring tools such as hyperic, nagios.which help to know more about how much of data being transferred / received across network. Customized scripting shall also be done.
Or, you could set up an instance to monitor your network traffic the old fashioned way with nagios, ect. perfsonar is a release from the DoE network ESNet that has a handful of basic tools included.