Determining the number of active nudes on an ethernet network by

Abstract

Delay times are modified in Ethernet network devices by adding an integer multiple of a delay interval to the minimum interpacket gap (IPG) interval, and decrementing a deferral counter storing the integer in each network station in response to detected activity on the media. Each station independently determines the number of stations active on the network media by counting the number of successful packet receptions following a corresponding detected collision. Once the number of detected collisions equals the number of stations (N) minus one, each station independently establishes a unique integer value from the range of zero to the number of detected collisions, i.e., up to the number of stations (N) minus one, by resetting the deferral counter to (N-1) after a successful transmission, and by decrementing the deferral counter upon detection of a successful transmission without collision by another station. The unique integer value ensures that each station has a different delay interval in accessing the media after sensing deassertion of the receive carrier. Each network station also includes a deferral timer that counts the maximum delay interval of (N-1) delay intervals plus the minimum IPG value, and thus establishes a bounded access latency for a half-duplex shared network.