Question
Suppose that the WFQ scheduling policy is applied to a buffer that supports three classes, and suppose the weights are 0.5, 0.25, and 0.25 for the three classes.
a. Suppose that each class has a large number of packets in the buffer. In what sequence might the three classes be served in order to achieve the WFQ weights? (For round robin scheduling, a natural sequence is 123123123 . . .).
b. Suppose that classes 1 and 2 have a large number of packets in the buffer, and there are no class 3 packets in the buffer. In what sequence might the three classes be served in to achieve the WFQ weights?
Answer
a)
The WFQ (Weighted Fair Queuing) scheduling is a circular order a round roubin strategy in ascending order depends on weights.
Assume the three classes weights are 0.5, 0.25, and 0.25 respectively.
If same weight have for two or more classes then give highest order is the first preference class.
The sequence order that the three classes served is :1 2 1 3 1 2 1 3….
Another possible sequence order that the three class are: 1 1 2 1 1 3 1 1 2 1 1…
b)
Consider the classes 1 and 2 have a large number of packets in the buffer, and there are no class 3 packets in the buffer.
The sequence might the three classes be served in to achieve the WFQ weights are 1 1 2 1 1 2 1 1 2….
Another sequence sequence might the three classes be served in to achieve the WFQ weights are 1 1 3 1 1 3 1 1 …