Single company or organization owns this. They are usually LAN technologies. There can be multiple LANs in a campus or building linked together. They are sometimes known Intranet.
PRIVATE NETWORK ARCHITECTURE:
It performs autonomously from other networks. It generally adds one or few closely managed external joins. They may end access at connections.
EXTENDING PRIVATE NETWORK:
The big organizations may have multiple campuses or buildings. They can only establish cables on their own property. They can contract for leased lines from common carrier network.