Anyone know how I can figure out why my Primaries have been hammering themselves with traffic (TNS) directly from my Oracle External DB for more than a week?

I'm seeing tons of TNS packets going to each of my primaries, but I haven't changed anything recently (at least no one will admit it), and the logs in debug aren't telling me anything is wrong as far as I can tell.

Is there a log I'm missing?
loader, services, and zmd-messages don't show anything