Patent ID: 6973032

Claim:
A method of queue congestion control in a multi-stage switch, said multi-stage switch comprising at least one ingress linecard, a plurality of switch elements arranged from a first switch element to a last switch element, and at least one egress linecard, said method comprising: enqueuing a first data packet in an inbound queue in said ingress linecard; dequeuing said first data packet to said first switch element; enqueuing said first data packet in a first switch element queue in said first switch element; dequeuing said first data packet to said last switch element; enqueuing said first data packet in a last switch element queue in said last switch element, wherein said enqueuing comprises determining a last queue status parameter (QSP); dequeuing said first data packet to said egress linecard, said dequeuing further comprising communicating said last QSP to said egress linecard; enqueuing said first data packet in an output queue, said output queue having an output queue status; periodically combining said output queue status with said last QSP, forming a backpressure signal; communicating said backpressure signal to said ingress linecard; and selectively enqueuing a second data packet in said inbound queue in said ingress linecard, wherein said enqueuing is influenced at least in part by said backpressure signal.