H3C S3100-52P Operation Manual page 552

Operation Manual – QoS-QoS Profile
H3C S3100-52P Ethernet Switch
Figure 1-7 Diagram for WFQ queuing
Before WFQ is introduced, you must understand fair queuing (FQ) first. FQ is designed
for the purpose of sharing network resources fairly and optimizing the delays and delay
jitters of all the flows. It takes the interests of all parties into account, such as:
Different queues are scheduled fairly, so the delay of each flow is balanced
globally.
Both short and long packets are scheduled fairly. When there are multiple long
packets and short packets to be sent among different queues, the short packets
must be scheduled preferentially, so that the delay jitters of packets of each flow is
reduced globally.
Compared with FQ, WFQ takes the priority into account when calculating the
scheduling sequence of packets. Statistically speaking, WFQ assigns more scheduling
chances to high priority packets than those to low priority packets. WFQ can classify the
traffic automatically according to the session information of traffic including the protocol
types, source and destination TCP or UDP port numbers, source and destination IP
addresses, and priority values in the ToS field. WFQ also provide as many queues as
possible to accommodate each flow evenly. Thus, the delay of each flow is balanced
globally. When the packets dequeue, WFQ assigns the bandwidth to each flow on the
egress according to the traffic precedence or DSCP precedence. The lower the traffic
precedence is, the less bandwidth the traffic gets. The higher the traffic precedence is,
the more bandwidth the traffic gets. Finally, each queue is polled and the corresponding
number of packets is taken out to be sent according to the proportion of bandwidth.
You can use the WFQ algorithm to assign bandwidth to the output queues of a port, and
then decide which queue a traffic flows into according to the mapping between the COS
value of the traffic and the queue, and also deicide how much bandwidth is to be
assigned to each traffic.
3) WRR queuing
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Chapter 1 QoS Configuration