United States Patent 5,940,399
Aug. 17, 1999
Methods of collision control in CSMA local area network
The present invention discloses method and apparatus to improve bandwidth utilization and fairness in star topology, collision based networks such as CSMA/CD, IEEE 802.3, ETHERNET. In one embodiment of the invention, when a collision is detected, a multi-port repeater initiates a collision recovery scheme in which it schedules a transmission order for the ports involved in the collision. One end station or port is allowed to transmit at one time. All other ports are sent DEFER signal. In collision control scheme, in response to a collision, a multi-port repeater allows one port or end station to transmit based on a suitable transmission arbitration or scheduling algorithm. The end stations having a frame to transmit send the frame immediately when the channel is free. If the channel is deferred, the
end stations send a request-transmission indication to the repeater. The repeater then sends a NON-DEFER signal to the first scheduled station, and DEFER signal to all other end stations to prevent their transmission. In collision recovery and collision control schemes, end stations wait zero time for transmission when allowed by the repeater, thereby providing a deterministic access delay depending on the arbitration algorithm. |
