In general, in one aspect, the disclosure describes an apparatus that
includes a plurality of flow controllable queues containing data to be
transmitted. The queues are organized by flow. The apparatus also
includes a plurality of destinations to receive data from the plurality
of queues. The apparatus further includes a controller to continually
maintain an aggregate count of data ready for transmission to the
destinations and determine next queue to transmit data from based at
least partially on the aggregate counts.