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Pagina 1 di 8 Fundamentals of Communication Networks Prof. G. Maier Exam – 3rd September 2019 Surname Name Student ID Total time 2:15 Ex1 (6pt) Ex2 (6pt) Ex3 (6pt ) Ex4 (6 pt) Ques (8 pt) 1 - Exercise (6 points) Consider the network below, where links are twisted-pair cables. At time t=0, hosts A and B start sending the following sequences of packets (one immediately after the other): - From A, 3 packets with destinations: C, D, C - From B, 2 packets with destinations: C, D - The first packet from B crosses the routers R3-R1-R2, while the second packet from B crosses the routers R3-R2. All the packets from A follow the same route through R1-R2 All the packets have equal length, and each comprises a header of h=4 byte and a payload of p=26 byte. All the nodes operate in the store-and-forward mode. Using a time diagrams, compute the arrival time of each packet to destination. Pagina 2 di 8 Pagina 3 di 8 2 - Exercise (6 points) Consider the network below, in which the cost of each link is reported near the link. 1- Assume that the dashed link BL is planned but still not in operation. Apply the Dijkstra algorithm to compute the shortest-path tree form node M to all the other nodes. Draw the tree on the right of the table and fill-in the top routing table of M node. 2- Compute the maximum value of X that allows an affective reduction of the distances between M and the other nodes (when possible). Repeat point 1 and fill in the bottom table Routing table of M without link BL Dest. Next hop Cost Hop dist. A B C D E F G H I L N Routing table of M with link BL in operation  X = ……… Dest. Next hop Cost Hop dist. A B C D E F G H I L N Pagina 4 di 8 3 - Exercise (6 points) A private company owns the following IP addressing space: 139.2 7.80.0/22. The network is shown in the…