Loop Telecom AM3440 series, User Manual, Page: 62 / 70

CHAPTER 8 Appendix A: Quality of Service (QoS) Setup
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Scheduling > (C) WRR Weight Setup)
Weighted Round Robin (WRR) : When a port uses the WRR algorithm, the transmission scheduling
depends on the weight ratio of each queue. The port will read out data of the 4 queues in a round robin
way relying on the configured Weight Ratio. Accordingly, to have WRR function successfully, users
should configure the weight ratio for each queue, as the above screen shown. The queue with the
higher weight will be transmitted first, and the one gets the lowest weight will be forwarded last. For
example, the weight ratios of P0, P1, P2, and P3 are 7%, 13%, 27%, and 53% respectively. Hence,
since P3 has the highest weight, packets in P3 will be sent first. After P3 completes the transmission,
it’s the turn of P2, and then P1, and finally P0. Moreover, within all the packets been forwarded in a
round, 53% data come from P3, 27% from P2, 13% from P1, and 7% from P0. After one round, the port
goes back to P3 and repeats the round again and again. One thing should be noticed: ports adopting
WRR share common settings of Weight Ratio, rather than have their own.