Digital network including early packet discard mechanism with adjustable threshold

A routing node for use in connection with an ATM computer network including a plurality of routing nodes, the routing node being connected to selected ones of the other routing nodes, and at least some of the routing nodes being connected to one of a plurality of sources or one of a plurality of destinations, each packet having a unique path from its packet source to its packet destination through routing nodes, each routing node routing a packet generated by its source to one destination along only one path, each packet including a plurality of serially-transmitted cells, each cell having a virtual circuit used for identifying the unique path it is to travel from its packet source to its packet destination, said routing node comprising:

• A. a buffer for receiving and buffering cells to be transmitted to other routing nodes in the network or to a packet destination;
• and
• B. a buffer control for selectively enabling the buffer to receive and buffer cells, the buffer control enabling an early packet discard control arrangement in which, in response to the buffer contemporaneously buffering a selected threshold number of cells, it disables the buffer from receiving and buffering received cells which are related to packets for which it did not begin receiving cells prior to enabling the early packet discard control arrangement mechanism, the buffer control periodically adjusting the threshold number in relation to information corresponding to a rate at which said buffer is buffering cells over a selected period of time thereto, and an interval counter with a selected value k which determines time intervals when the threshold number of cells is periodically adjusted.

A method of operating a routing node, the routing node being for use in connection with an ATM computer network including a plurality of routing nodes, the routing node being connected to selected ones of the other routing nodes, and at least some of the routing nodes being connected to one of a plurality of sources or one of a plurality of destinations, each packet having a unique path from its packet source to its packet destination through routing nodes, each routing node routing a packet generated by its source to its destinations along only one path, the method including the steps of:

• A. receiving and buffering cells to be transmitted to other routing nodes in the network or to a packet destination in a buffer along only one path;
• B. selectively enabling the buffer to receive and buffer cells, in the process enabling an early packet discard control arrangement in which, in response to the buffer contemporaneously buffering a selected threshold number of cells, it disables the buffer from receiving and buffering received cells which are related to packets for which it did not begin receiving cells prior to enabling the early packet discard control arrangement mechanism, the threshold number being periodically adjusted in relation to information corresponding to a rate at which said buffer is buffering cells over a selected period of time prior thereto;
• and
• C. adjusting the threshold number after a predetermined time interval based on an interval counter with a selected value k which determines the time interval when the threshold number is adjusted.