Lab 09 Queuing Disciplinespdf In a Word Document with your

: Lab 09 Queuing Disciplines.pdf

In a Word Document with your name and the assignment number at the top,

Include a screen shot of your 2 simulation graphs (example: page 10).

Include a screen shot of your 3 simulation graphs (example: page 11).

Under the graphs answer the following question:

1) Analyze the graphs we obtained and verify the overlap of the Voice Packet Endto-End Delay and Voice Packet Delay Variation graphs. Compare the three queuing disciplines and explain their effect on the performance of the three applications.

Solution

As the complete graph for first part of the question was not provided, lets look at the queuing disciplines:

1. First-in-first-out (FIFO) queuing. 2. Priority queuing(PQ) 3. Weighted-Fair queuing.(WFQ)

FIFO is an acronym for First In First Out .This expression describes the principle of a queue or first-come first serve behavior: what comes in first is handled first, what comes in next waits until the first is finished etc. Thus it is analogous to the behavior of persons “standing in a line” or “Queue” where the persons leave the queue in the order they arrive. First In First Out (FIFO) is the most basic queuing discipline. In FIFO queuing all packets are treated equally by placing them into a single queue, then servicing them in the same order they were placed in the queue. FIFO queuing is also referred to as First Come First Serve (FCFS) queuing

[2]. Priority Queuing assigns multiple queues to a network interface with each queue being given a priority level. A queue with higher priority is processed earlier than a queue with lower priority. Priority Queuing has four preconfigured queues, high medium, normal and low priority queue. By default each of these queues has 20, 40, 60 and 80 packets capacity.

[3] The idea of the fair queuing (FQ) discipline is to maintain a separate queue for each flow currently being handled by the router. The router then services these queues in a roundrobin manner. WFQ allows a weight to be assigned to each flow (queue). This weight effectively controls the percentage of the link’s bandwidth each flow will get. We could use ToS bits in the IP header to identify that weight.