IP Quality of Service

MDRR Implementation 119

Queue 1 is served next. It deficit counter is initialized to 3000. This allows three packets to

be sent, leaving the deficit counter to be 3000 – 1500 – 500 – 1500 = –500. Figure 5-14

shows the queues and the deficit counters at this stage.

Figure 5-14 MDRR After Serving Queue 1, Its First Pass

Queue 0 is the next queue serviced and sends two packets, making the deficit counter

1500 – 1000 – 1500 = –500. Because the queue is now empty, the deficit counter is reset

to 0. Figure 5-15 depicts the queues and counters at this stage.

Queue 1 serves the remaining packet in a similar fashion in its next pass. Because the queue

becomes ...