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 tolerating control link faults in a packet communications switch fabric. The method comprises: accepting information packets including a plurality of cells, at a plurality of port card ports, the plurality of information packets addressing a plurality of port card ports; selectively connecting port card ports to port card backplane data links; in response to backplane control link communications, selectively connecting port card backplane data links and crossbars; sensing a connection fault in a control link; and, in response to sensing the control link fault, reselecting connections between the port card ports and the port card backplane data links. In some aspects, selectively connecting port card backplane data links and crossbars includes: for a particular backplane data link, fixedly connecting each port card to a corresponding interface of an assigned crossbar; and, selectively enabling the connection to each crossbar.

Abstract: A system and method have been provided for synchronizing the timing of line cards and switch cards in a broadband switch. Synchronization is accomplished using an auxiliary data link between the line and switch cards. One of the switch cards is selected as the master switch card. The master switch card receives timing information from the line cards, and in turn, sends timing correction signals to each of the line cards. Each line card acquires synchronization using its respective timing correction. A master line card is selected from among the line cards, and the slave switch cards adopt the timing of the master line card, becoming synchronized to the master switch card.