receiving a plurality of data packet flows, each received data packet flow of the plurality having respective customer-assigned service requirements, including definition of service, priority, delay, jitter and bandwidth characteristics;

directing the received data packet flows to corresponding egress queues;

allocating amounts of bandwidth to each data packet traffic flow of the plurality of data packet flows in accordance with the respective customer-assigned service requirements by:

selecting amounts of bandwidth assigned to each of the egress queues and determining an amount of data to be released from each egress queue;

monitoring an occupancy of each egress queue to determine an amount of unused bandwidth that is allocated to but not used in any given egress queue;

managing the unused bandwidth in a repository for unused bandwidth, so as to be available for allocation to other egress queues that can utilize the unused bandwidth; and

making at least a portion of the unused bandwidth available from the repository for use by another egress queue that has more data to send than the allocated bandwidth will permit; and

scheduling a departure order of the each of the plurality of data packet traffic flows from the switch/router to a common communication link based upon and adapted to the respective customer-assigned service requirements, by selecting, independently of bandwidth allocation, at least one of an order and a priority of data packet release from the egress queues to the common communication link,

whereby the switch/router provides differentiated services for the plurality of data packet traffic flows, while simultaneously substantially filling a total data packet flow capacity utilization of the common communication link.