Automatic edge port and one way connectivity detection with rapid reconfiguration for shared media in spanning tree configured bridged Local Area Networks

For a network comprising a plurality of communication links connected by a plurality of network devices said network being capable of transmitting frames of data, a network device comprising:

• a plurality of ports coupled to communication links in the network;
• topology management resources which manage the plurality of ports to select an active topology that is loop-free by forwarding, that is transmitting and or receiving, frames through one or more ports in the plurality of ports and not forwarding frames through the zero or more other ports in the plurality of ports;
• additional logic for a first port of said network device that transmits a control message through said first port to other ports of other network devices said other ports being attached to the same media as said first port said message instructing each said other network device to ensure the topology is loop-free by ceasing to transmit frames of data through ports in the plurality of ports composing said other network device within a certain time or to transmit a control message of disagreement to said first port within a certain time said additional logic causing said first port to transmit and receive frames after a certain time has elapsed if no control message of disagreement has been received;
• additional logic for said network device that receives a first control message on a first port instructing said network device to ensure the topology is loop-free and acts within a certain time to cease transmitting frames other than control messages through said first port or to cease transmitting frames other than control messages through other ports or to transmit a control message of disagreement with said first control message.