Avoidance of false re-initialization of a computer network

A communications system comprising:

• a token controlled communications ring;
• at least a first station and a second station, said first station and said second station each having an address, said first and said second stations capable of transmitting frames onto said ring, said frames having source addresses placed therein, said first and second stations each having a timer capable of storing a time interval, and said second station capable of detecting transmissions on said ring, and said second station capable of taking predetermined action in the absence of a frame transmission for a predetermined time interval;
• means for said first station to transmit a plurality of client frames onto said ring;
• means for said first station to transmit a token preserver frame between selected client frames after which transmission of said client frame continues;
• means, responsive to said second station receiving said token preserver frame, for said second station to reset said timer for said predetermined time interval and avoid said second station taking said predetermined action in the absence of receipt by said second station of client frames transmitted by said first station.

A communications system, comprising:

• a first local area network;
• a second local area network;
• a bridge for forwarding frames from said first local area network to said second local area network;
• a first station on said first local area network, said first station capable of transmitting frames having a selected address placed within a source address field of said frames;
• a second station on said second local area network, said second station having at least one address used for source address stripping of frames from said second local area network;
• at least a third station on said second local area network, said at least a third station capable of receiving frames transmitted onto said second local area network by said bridge after said frames transmitted by said bridge first pass through said second station, said at least a third station having a TVX timer capable of initiating predetermined action in the event that no frame is detected by said at least a third station during a TVX time period;
• means for said bridge to transmit token preserver frames onto said second local area network, said token preserver frames capable of resetting a TVX timer in said at least a third station, and said token preserver frames capable of not being stripped by said second station;
• and,
• in the event that frames transmitted by said first station are addressed to said at least a third station and said selected address placed within a source address field of said frames by said first station is contained in said at least one address used by said second station for source address stripping, said frames being stripped by said second station before said frames reach said third station, said token preserver frame preventing said TVX timer in said at least a third station from expiring and thereby preventing said at least a third station from initiating said predetermined action.

A communications system, comprising:

• a first local area network;
• a second local area network;
• a bridge for forwarding frame from said first local area network to said second local area network;
• a first station on said first local area network, said first station capable of transmitting frames having a selected address placed within a source address field of said frames;
• a second station on said second local area network, said second station having at least one address used for source address stripping of frames from said second local area network;
• at least a third station on said second local area network, said at least a third station capable of receiving frames transmitted onto said second local area network by said bridge after said frames transmitted by said bridge first pass through said second station, said at least a third station having a TVX timer capable of initiating fault recovery and ring initialization in the event that no frame is detected by said at least a third station during a TVX time period;
• means for said bridge to transmit token preserver frames onto said second local area network, said token preserver frames capable of resetting a TVX timer in said at least a third station, and said token preserver frames capable of not being stripped by said second station;
• and,
• in the event that frames transmitted by said first station are addressed to said at least a third station and said selected address placed within a source address field of said frames by said first station is contained in said at least one address used by said second station for source address stripping, said frames being stripped by said second station before said frames reach said third station, said token preserver frame preventing said TVX timer in said at least a third station from expiring and thereby preventing said at least a third station from initiating said fault recovery and ring initialization.

An apparatus for a station in a communications network, comprising:

• a plurality of stations capable of transmitting frames onto said network, and said stations capable of detecting transmissions on said network, and said stations capable of taking predetermined action in the absence of detecting a frame transmission for a predetermined first time interval, and a first timer for measuring said predetermined first time interval;
• means for originating information frames onto said network;
• timing means for measuring a second predetermined time interval, said second predetermined time interval being chosen to be less than said first predetermined time interval;
• and,
• reset means for transmitting a reset frame onto said network by a selected station at times in response to said timing means and said reset frames being transmitted at intervals substantially equal to said second predetermined time interval, and said reset frames being capable of causing a station to reset said first timer to a beginning value, said reset means capable of transmitting said rest frames between frames transmitted by said originating means.