Method and apparatus for traffic congestion control in a communication

Abstract

A technique for controlling access to a bridge connected to at least two networks, such that buffer memory requirements are minimized. For at least one target network of the two networks, two dynamic lists are maintained, to keep track of data packets received from the target network and not yet forwarded, and to keep track of data packets stored for forwarding to the target network, but not yet forwarded. The target network uses a half-duplex medium and a CSMA/CD (Carrier Sense Multiple Access with Collision Detection) protocol. The invention operates by adjusting network protocol parameters used in the target network, to either guarantee or deny priority to the target network in the event of a collision, based on the continually observed status of the two lists. One of the adjustments modifies a backoff value that determines the amount of time that the bridge device will wait, in the event of a collision, before attempting to retransmit a data packet. Another adjustment used is to apply backpressure to the target network, in the form of a carrier signal, to deny its use by other devices when buffer storage in the bridge is already full and there are no data packets ready to send to the target network.