Patent ID: 7453810

Claim:
At a communication node for routing a protocol data unit (PDU) along a datapath established between an ingress port and an egress port through a switch fabric (SF) egress port, a backpressure mechanism, comprising: a backpressure bus for establishing an out-of-band bidirectional connection between said ingress port and said egress port; egress logic for estimating a congestion state indication characterizing the congestion along said datapath; and ingress logic for controlling transmission of said PDU along said datapath based on said congestion state indication, wherein said egress logic transmits said congestion state indication to said ingress logic over said backpressure bus, while said ingress logic transmits traffic statistics to said egress logic over said backpressure bus, said congestion state indication includes a SF queue congestion state that measures the congestion at said egress port, additional congestion data regarding a SF queue are written at said SF egress port, said additional congestion data are read, and said SF queue congestion state is adjusted according to said additional congestion data.