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Fundamentals of Communication Networks Prof. A. Pattavina III exam – 24 June 2020 Surname and name: (upper case) Signature: (your readable signature) Matricola ID: Pag. 1/8 1 - Exercise* (7 points) Two stations, A and B, communicate through a router R with link capacities C A-R = 100 Mbit/s, CR-B = 200 Mbit/s with both fiber optic links having length l = 2 km. The forwarding mechanism is store and forward without processing delay. A file of D = 0.75 kbyte is transferred between the two stations in packets with payload Lp = 1000 bits and header length Lh = 25 byte. Acknowledgment packets have length La = 25 byte. Calculate the total transfer time (between transmission of the first bit and reception of the last bit) in the following cases: a) Packets are transmitted without errors one after the other b) Packets are transferred without errors with a Stop and Wait protocol on each link c) Packets are transferred without errors with a Stop and Wait protocol executed end-to-end. d) Packets are transferred using an ACK-only protocol executed end-to-end with arbitrarily large transmitter and receiver window with one error occurring on the first packet transmitted. The timeout is assumed equal to the minimum theoretical value. . * Fundamentals of Communication Networks Prof. A. Pattavina III exam – 24 June 2020 Pag. 2/8 Fundamentals of Communication Networks Prof. A. Pattavina III exam – 24 June 2020 Pag. 3/8 Fundamentals of Communication Networks Prof. A. Pattavina III exam – 24 June 2020 Pag. 4/8 2 - Exercise (8 points) A router has 3 network interfaces with the following IP address, Netmask, maximum transmission unit (MTU) Interface IP address Netmask MTU (byte) eth0 191.3.12.13 255.255.255.128 500 eth1 191.3.12.145 255.255.255.128 1500 eth2 191.3.13.62 255.255.255.192 1000…