Patrick A Daley

US Patent:

53134540, May 17, 1994

Filed:

Apr 1, 1992

Appl. No.:

7/861761

Inventors:

Lionel A. Bustini - Campbell CA
Patrick D. Daley - Belmont CA
Charles M. Corbalis - Milpitas CA

Assignee:

Stratacom, Inc. - San Jose CA

International Classification:

H04L 1256
H04L 1202

US Classification:

370 13

Abstract:

A feedback control system for congestion prevention in a cell (packet) switching communication network is described. Congestion control is accomplished by controlling the transmission rate of bursty traffic in the presence of high priority, voice, low speed statistical, high speed deterministic and multicast data. Because bursty traffic is relatively insensitive to delay, adequate buffer capacity can be provided at the network nodes in order to minimize bursty data cell loss. By monitoring the buffer queue lengths at the nodes, a control signal can be generated at each intermediate node indicating the state of congestion. Excess queue length indicates incipient congestion while short queue lengths indicate excess capacity. Queue status is forwarded to the destination node where it is interpreted and sent back to the source node as a feedback rate control signal using a 2-bit code. The source node regulates the rate of bursty data transmission over the cell network in accordance with the feedback control signal thus minimizing congestion and concomitant data loss while efficiently utilizing available network bandwidth.