Answer Happy

PLEASE TURN OVER Q1. a) Suppose that seven packets arrive at a router according to the pattern in Table 1. Packet ► ס ס ס ח ד ם Input Arrival time Queue 1 0 1 5 1 6 2 1 2 2 3 3 3 4 Table 1 Packet Length 2 2 3 5 3 6 9 Give the packet output order if weighted fair queuing with a weight of 3 for input queue 3 is used. (6 marks) b) Fair queuing is equivalent to first-in first-out when all the packets in the queues have the same length. Prove this statement if it is true or give a counter-example if it is false. (4 marks) c) The random early detection (RED) algorithm was introduced in the paper S. Floyd and V. Jacobson, "Random early detection gateways for congestion avoidance", IEEE/ACM Transactions on Networking, vol. 1, no. 4, pp. 397-413, Aug. 1993, doi: 10.1109/90.251892. Suppose that the current value of count is zero and that the maximum value for the packet marking probability p is equal to 0.1. Suppose also that the average queue length is halfway between the minimum and maximum thresholds for the queue. Calculate the probability that the next packet will not be dropped. (10 marks)