Abstract: A system and method are provided for tolerating data line faults in a packet communications switch fabric. The method comprises: accepting information packets including a plurality of cells, at a plurality of ingress port card ports, the plurality of information packets addressing a plurality of egress port card ports; selectively connecting port card ports to port card backplane data links; selectively connecting port card backplane data links and crossbars; sensing a connection fault in a backplane data link; in response to sensing the fault, reselecting connections between the port card ports and the port card backplane data links; in response to reselecting connections between the port card ports and the port card backplane data links, serially transferring packets through the port cards; serially transferring packets through the crossbars to the egress port cards; and, suspending use of the faulty connection.

Abstract: A system and method are provided for resynchronizing backplane link management credit counters in a packet communications switch fabric. The method comprises: at an input port card ingress port, accepting information packets including cells and cell headers with destination information; modifying the destination information in the received cell headers; routing information packets between the input port card and output port cards on backplane data links through an intervening crossbar; at the input port card, maintaining a credit counter for each output port card channel; decrementing the counter in response to transmitting cells from the input port card; generating credits in response to transmitting cells from an output port card channel; sending the generated credits to increment the counter, using the modified destination information; and, using the generated credit flow to resynchronize the credit counter.

Abstract: A system and method are provided for configuring interface bandwidths in a packet communications switch fabric. The method comprises: interfacing data links with a first plurality of traffic managers (TMs); differentiating port card interface ports into a first plurality of subchannels associated with the first plurality of TMs; and, communicating packets information with the TMs at a first plurality of data rates corresponding to the first plurality of subchannels. More specifically, differentiating port card interface ports into a first plurality of subchannels associated with the first plurality of TMs includes: differentiating a second plurality of ingress data links into a third plurality of ingress subchannels associated with a third plurality of ingress traffic managers (iTMs); and, differentiating a fourth plurality of egress data links into a fifth plurality of egress subchannels associated with a fifth plurality of egress TMs (eTMs).

Abstract: A system and method are provided for controlling packet header information in a packet communications switch fabric. The method comprises: programming the cell header overhead (OH) field definitions; accepting a packet including a plurality of cells and corresponding cell headers, each cell header including a plurality of overhead fields; defining the cell header OH fields; and, transmitting the packet. Defining the cell header OH fields includes defining cell header OH field location, position, meaning, structure, and length. In other aspects, the method comprises redefining the cell header overhead fields, once they are accepted. For example, the OH field information can be modified, relocated, or an OH field can be added to the cell header. In yet other aspects, the OH field information can be extracted and/or reformatted.

Abstract: A system and method are provided for communicating control information in a switch fabric. The method comprises: on a switch card, establishing a plurality of crossbars controlled by an arbiter; initiating a control message; and, distributing the control message on a switch card token bus connecting the crossbars and arbiter elements. Distributing the control message on a switch card token bus connecting the crossbar and arbiter elements includes daisy-chain connecting the elements with a cyclical bus. In some aspects of the method, establishing a plurality of crossbars controlled by an arbiter includes identifying each element with a unique address. Then, initiating a control message includes initiating a control message with an attached address. Distributing the control message on a switch card token bus includes the substeps of: daisy-chain passing the control message between elements; and, terminating the message at an element having an address matching the address attached to the control message.

Abstract: A credit-based system and method are provided for managing backplane traffic flow in a packet communications switch fabric. The method comprises: accepting information packets including cells and cell headers with destination information; modifying the destination information in the received cell headers; routing information packets between an input port card and output port cards on backplane data links through an intervening crossbar; at the input port card, maintaining a credit counter for each output port card channel; decrementing the counter in response to transmitting cells from the input port card; generating credits in response to transmitting cells from an output port card channel; and, using modified destination information, sending the generated credits to increment the counter. In some aspects, modifying the destination information in the received packet headers includes: extracting the output port card termination from the card field; and, inserting the input port card source in the card field.

Abstract: A system and method are provided for communicating TDM communications through a packet switch fabric. The method comprises: accepting native TDM frames; converting the native TDM frames to fabric-cellified TDM frames; differentiating the cells of each frame into time slots; interleaving the frame time slots; TDM scheduling the interleaved frame time slots; and, routing the interleaved frame time slots between input port cards and output port cards on backplane data links through an intervening crossbar. TDM scheduling the interleaved frame time slots includes: an input port card ingress memory subsystem (iMS) receiving a first TDM configuration schedule including interleaved frame time slots cross-referenced to backplane transmission times; and, an output port card egress MS (eMS) receiving a second TDM configuration schedule including interleaved frame time slots cross-referenced to egress channel transmission times. Then, the routing is performed in response to the TDM schedules.

Abstract: A system and method are provided for cut-through packet routing in a packet communications switch fabric. The method comprises: accepting information packets addressed to a plurality of output port card egress ports at an input port card ingress port; routing information packets between port cards on backplane data links through an intervening crossbar; maintaining a credit counter for each port card egress destination, at the input port card; decrementing the counter in response to transmitting cells in a packet from the input port card; and, incrementing the counter in response to transmitting cells from the packet at the output port card. In some aspects of the method, accepting information includes buffering the packets in an ingress memory subsystem (iMS). Routing information includes the iMS transmitting buffered packets on a selected backplane data link. Decrementing the counter includes the iMS communicating with the iPQ in response to transmitting a cell.

Abstract: A system and method are provided for tolerating data line faults in a packet communications network. The method comprises: serially transmitting information packets from at least one traffic manager (TM); at a switch fabric, accepting information packets at a plurality of ingress ports, the information packets addressing destination port card egress ports; selectively connecting port card ingress ports to port card egress ports; serially supplying information packets from a plurality of port card egress ports; sensing a connection fault between the switch fabric and the TM; and, in response to sensing the fault, reselecting connections between the switch fabric port card ports and the TM. Some aspects comprise: an ingress memory subsystem (iMS) receiving cells on an ingress port exceeding an error threshold. Then, reselecting connections between the port card ports and the TM includes the iMS sending a message to the iTM identifying the faulty ingress connection.