I have two CentOS servers (one is an app server, the other is a DB) communicating over a port. Every once in a while, the application server starts broadcasting that the port connected to the DB has a "ZeroWindow" (window size of zero) status (as seen via tcpdumps).
When this happens, the port on the DB server has its Send Q fill up with bytes, since nothing is on the App Server side is reading them.
How can I tell what is causing my app server to send the port into this "ZeroWindow" state when this happens?