The present invention provides a method and an apparatus for scheduling a flow on an output link among a plurality of flows of incoming packet traffic at a network device associated with a data network. A scheduler comprises scheduler logic that uses a credit counter per flow to keep track of the service difference received between two or more flows and selects the flow for service next that has the maximum credit value. The scheduler logic updates an amount of credit value in a counter of the next flow with the front-end packet currently being served among the first and second flows with a value that substantially equals a packet size value divided by a flow weight value of the front-end packet currently being served. The scheduler logic further updates an amount of credit value in the first and second counters of the first and second flows having packets waiting with a value that substantially equals the size of the front-end packet currently being served.