Ring network security system with encoding of data entering a subnetwork and decoding of data leaving the subnet work

摘要

A system for securing communications between devices connected to a ring network. In accordance with the present invention, when a message frame is passed around the ring network, a gate keeper circuit associated with at least one port of a hub determines whether the message frame is intended for any of the nodes connected to that port. If the message frame is not intended for any of the nodes connected to that port, the message frame is encoded before it exits the hub through the port to traverse the subnetwork connected to the port, and decoded after it reenters the hub through the port. If and only if at least one node on the subnetwork connected to the port is intended to receive the message frame, then each node connected to that port can read the message frame.