US 5,689,500 AGranted

Multistage network having multicast routing congestion feedback

AssigneeLucent Technologies Inc.

InventorsFabio Massimo Chiussi, Joseph George Kneuer, Vijay Pochampalli Kumar

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Abstract

Multicasting of an ingress cell received at one of a plurality of input ports is provided through a multistage network to a plurality of output ports. The received ingress cell at a first input port includes a data payload and information identifying one or more routing queues to which a single copy of the data payload is to be outputted. A backpressure queue assignment is identified for the first ingress cell, the backpressure queue assignment identifying a backpressure indicator indicative of the congestion level at at least one routing queue of a subsequent stage. Using the backpressure indicator, it is determined if the first ingress cell is to be outputted from one or more of the routing queues. Thereafter, the first ingress cell is outputted from one or more of the routing queues when the congestion level is below or equal to a first threshold.

Claims39

Dependent claims

Apparatus for multicasting an ingress cell received at one of a plurality of input ports, connectable through a multistage network, to a plurality of output ports, comprising:

(a) means for receiving a first ingress cell of a multicast at a first input port of a first stage, the ingress cell including a data payload and information identifying a plurality of routing queues output ports to which a copy of the data payload is to be sent;
(b) means for storing the data payload in memory;
(c) in the first stage, a plurality of routing queues including at least one queue for each of the output ports;
(d) means for identifying a backpressure queue assignment for the first ingress cell, the backpressure queue assignment identifying a backpressure indicator indicative of the congestion level for at least one but not all of destination routing queues of a subsequent stage associated with all output ports of a multicast;
(e) means for determining, using the backpressure indicator, if the first ingress cell is to be outputted from one or more routing queues of the first stage;
and
(f) means for outputting the first ingress cell from the one or more routing queues to all destination routing queues of the subsequent stage when the congestion level is below or equal to a first threshold and inhibiting all outputting of the first ingress cell when the congestion level is above the first threshold level.

4 more elements

A method of multicasting an ingress cell received at one of a plurality of input ports, connectable through a self-routing multistage network, to a plurality of output ports, said method comprising the steps of

(a) receiving a first ingress cell of a multicast at a first input port of a first stage, the ingress cell including a data payload and information identifying a plurality of routing queues, at least one for each of the output ports of the multicast, to which a copy of the data payload is to be outputted,
(b) storing the data payload in said plurality of routing queues,
(c) identifying a backpressure queue assignment for the first ingress cell, the backpressure queue assignment identifying a backpressure queue containing a congestion value indicative of the congestion level for at least one but not all of the routing queues of a subsequent stage associated with all output ports of the multicast,
(d) determining, using the congestion value stored in the backpressure queue, if the first ingress cell is to be outputted from the one or more routing queues, and
(e) outputting the first ingress cell from one or more routing queues to all destination routing queues of the subsequent stage when the congestion level is below or equal to a first threshold and inhibiting all outputting of the first ingress cell when the congestion level is above the first threshold level.

2 more elements

Dependencies are inferred from the claim text.