Patent ID: 7978690
Filing Date: 2011-07-12
Classification: H04L

Abstract:
1. A crossbar switch comprising: a crossbar fabric having N sending and M receiving ports, wherein N and M are integers; at least one sending port card coupled to one or more sending ports, each sending port card comprising buffer space for storing sent data cells until an acknowledgement is received; at least one receiving port card coupled to one or more receiving ports; at least one control unit coupled to the at least one sending and at least one receiving port cards via discrete control channel links, and link control means to use the discrete control channel links to relay C acknowledgements simultaneously between at least one receiving port card and at least one sending port card, wherein C is a clustering factor and C receiving ports are clustered on a single receiving port card so that such a receiving port card in a single time-step can receive up to C data cells from C sending port cards simultaneously, wherein said link control means to use the discrete control channel links to relay acknowledgements between the at least one sending and at least one receiving port cards comprises a reliable delivery queue (RDQ) and acknowledgement match unit on each sending port card to process an acknowledgement received at a sending port card, to trigger retransmissions, and to provide information about acknowledged data cells, and wherein each RDQ entry stores a retransmission deadline based on a sum of a current time and a round-trip time, wherein the retransmission is triggered when at least one of the current time exceeds the retransmission deadline and a sequence number of an acknowledgement on the control channel link mismatches with a sequence number of a corresponding head-of-line descriptor in the RDQ.