Multicast and unicast scheduling for a network device

A method of combining multicast and unicast scheduling in a network device comprising the steps of:

• scheduling multicast cells for transmission among a plurality of interfaces of a crossbar by performing a multicast cell scheduling cycle for a plurality of classes of service that are supported by the network device;
• and
• scheduling unicast cells for transmission among the plurality of interfaces at a lower priority than the multicast cells scheduled by the multicast cell scheduling cycle by performing a unicast cell scheduling cycle for the plurality of classes of service using only those interfaces that remain unmatched after completion of the multicast cell scheduling cycle.

A method of combining multicast and unicast scheduling comprising the steps of:

• scheduling multicast cells for transmission among a plurality of interfaces of a crossbar by performing a multicast cell scheduling cycle including a executing scheduling iterations for a plurality of classes of service that are supported by the network device and producing availability information indicative of those of the plurality of interfaces that remain available for scheduling;
• and
• scheduling unicast cells for transmission among the plurality of interfaces at a lower priority than the multicast cells by performing a unicast cell scheduling cycle after the multicast cell scheduling cycle and using only those interfaces identified by the availability information.

A method of performing multicast and unicast scheduling in a network device, the method comprising the steps of:

• during a first predetermined set of scheduling timeslots of a set of possible scheduling timeslots, performing both multicast cell scheduling and unicast cell scheduling, the multicast cell scheduling and the unicast cell scheduling operating in parallel and independent of each other;
• and
• during a second predetermined set of scheduling timeslots of the set of possible scheduling timeslots, performing unicast cell scheduling based upon results of the multicast cell scheduling completed during a previous scheduling timeslot.

A method of combining multicast and unicast scheduling comprising the steps of:

• performing a multicast cell scheduling cycle during timeslot t for multicast cells that are to be transmitted across a fabric of a network device during timeslot t+n, the fabric coupling each of a plurality of input ports to each of a plurality of output ports, the multicast cell scheduling cycle including a scheduling iteration for each class of service supported by the network device and producing availability information indicative of those of the plurality of input ports and output ports that remain available for scheduling during timeslot t+n;
• and
• performing a unicast cell scheduling cycle during timeslot t+n based upon the availability information, the unicast cell scheduling cycle scheduling unicast cells for transmission across the fabric during timeslot t+n.