Apparatus and method for programmably modifying a limit of a retry counter in a network switch port in response to exerting backpressure

摘要

A network switch having switch ports for communication of data packets with respective computer network nodes according to CSMA/CD protocol that resets a retry counter for counting data packet transmission attempts within any one of the respective switch ports if backpressure is asserted by that port. A retry limit value for the retry counter is selectively modified according to programmed information to ensure that the total number of retrys does not exceed a maximum total number of allowable retrys. Resetting the retry counter within a port after assertion of backpressure affords the port a greater probability of transmitting earlier under the CSMA/CD protocol, thus more quickly relieving congestion which may occur in the network switch. Selective modification of the retry limit value according to programmed information adds flexibility to vary the maximum total number of allowable retrys based upon current network switch conditions or the priority of a particular data packet.