Jingle node install question

I am evaluating Openfire with the Jingle Node plug in as a solution to provide collaboration services to text/voice/video chat and desktop sharing to users on our private network (192.168.x.x). We do not need/want to communicate with the outside world. We simply want clients on this provate network (using the jitsi client) to be able to communicate with each other.

That being said, I have installed the Openfire server with a private IP (192.168.250.29) and also downloaded and installed the Jingle Node plug in. All the documentation I can find for the Jingle Node plug in and the Jingle Node config screen within Openfire states “Jingle Nodes requires a public IP address”.

Question is, why? In our example we want the network to be complete cut off from the rest of the world but yet still provide these services. Is this possable?

Thanks much in advance to all.