Be able to configure timeout on virtual switch ports

Hi,

I am using a docker container to run regression tests (written in Python) using omniORB to communicate to the DUT.

Because of the omniORB interface to the DUT, we need to log in to the DUT before any API call is excepted and so we do. But sometimes, the opened TCP connection to the omniORB endpoint in the DUT is idle for multiple minutes after the initial logon. When finally, after for example 5 minutes, the regression script uses the IIOP API again, I believe vpnkit is opening a new connection from the OS X host to the DUT. But for the DUT, this new connection requires an logon first before any other API calls are excepted. However, from a regression script point of view, the connection has been established and has not changed. Result: failure of the script.

The README.md of this repo explains that the virtual switch will close the port when activity is absent for some time (not defined in README.md how long). This breaks the above regression framework we are using and I've already tried to reduce the keepalive timers in the container (to make sure there is at least data being sent over the idle connection) but for some reason that did not work.

So another way around the issue would be if I could extend the timeout in the virtual switch before it decides to open a new connection. Is there a way to do so?

Read README.md to confirm the documented virtual-switch port timeout, then trace the virtual switch entry point that closes idle connections and check how its settings are supplied. Done means the timeout can be configured for this use case and the available setting is documented, with coverage added if the relevant test location is found.