Huawei v200r001 user manual Configuration of Congestion Management, Configuring PQ

User Manual - Configuration Guide (Volume 3)	Chapter 3
Versatile Routing Platform	Congestion Management

IV. WFQ

Queue

queue 1

queue 2

Classification

Packets leaving the interface

Packets sent from this interface

...

queue NDequeuing dispatch

Figure QC-3-5Schematic diagram of weighted fair queuing

WFQ embodies the weight on the basis of ensuring fairness, and the amount of the weight depends on the IP Precedence brought in the IP packet headers. As shown in the figure above, WFQ classifies the packets according to the flow (packets with the same source IP address, destination IP address, source port number, destination port number, protocol number and TOS), and each flow is allocated with to one queue. When outgoing from the queue, WFQ allocates the bandwidth to be occupied at the exit by each flow according to the precedence of the flow. The smaller number of the precedence, the less bandwidth of the flow. The bigger number of the precedence, the more bandwidth of the flow.

For example, there are currently 8 flows at the interface, with priority of 0, 1, 2, 3, 4, 5, 6 and 7.So, the total bandwidth allocated is the sum of all priorities (flow priority + 1).

That is, 1+2+3+4+5+6+7+8=36

The proportion of bandwidth occupied by each flow is: (priority number +1) / (all priorities (flow priority + 1)) That is, each flow can acquire the bandwidth as follows: 1/36, 2/36, 3/36, 4/36, 5/36, 6/36, 7/36, 8/36.

Another example: there are 4 flows currently, the priority of three flows is 4, and the priority of one flow is 5, then the total bandwidth allocated is:

(4 + 1) * 3 + (5 + 1) = 21

Therefore, the bandwidth for the three flows with priority 4 is 5/21, and the bandwidth for the flow with priority 5 is 6/21.

3.2 Configuration of Congestion Management

3.2.1Configuring PQ

I.PQ Configuration task list

Configuration task list of priority queue is as follows:

z Configure the priority queue

z Apply priority queue at the interface

z Maintain and monitor the priority queue

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