Patent ID: 7397809

Claim:
A hybrid queue for an output port of a protocol data unit (PDU) switching node comprising: a. a first input first output (FIFO) queue configured to store multicast FIFO entries, each multicast FIFO entry further comprising a multicast switching data unit (SDU) descriptor pointer and an inter-departure-counter specifier holding a number of unicast SDUs to be serviced ahead of the multicast SDU entry; each multicast SDU descriptor comprising a diversity field for specifying the number of output ports the multicast PDU is to be conveyed through; b. a linked list queue defined by a plurality of unicast SDU entries, each unicast SDU entry further comprising a unicast SDU descriptor, each unicast SDU descriptor further comprising a next SDU descriptor pointer; c. a unicast forwarding request arrival counter for counting unicast PDU forwarding requests received between multicast FIFO entries, the arrival counter being incremented with each unicast PDU forwarding request arrival, the arrival counter being decremented with each serviced unicast SDU entry if the multicast FIFO queue is empty, the value of the arrival counter being further copied to the inter-departure-counter of a subsequently received multicast FIFO entry upon receiving a multicast PDU forwarding request and the value of the arrival counter being reset to zero thereafter; d. a unicast PDU departure counter for counting unicast PDU departures between multicast PDU departures in servicing the unicast linked list queue if the multicast FIFO queue is not empty; and e. a sequencer for servicing unicast linked list entries and multicast FIFO queue entries, the sequencer servicing a next multicast FIFO entry if the value of the departure counter equates the value held in an inter-departure-count held in said next multicast FIFO entry and otherwise servicing the next unicast linked list entry pointed to by a head-of-line pointer specifier; the combined unicast and multicast PDU forwarding request queuing benefiting from bandwidth efficient FIFO queuing of multicast forwarding requests, and memory storage efficient linked list queuing of unicast PDUs.