20190625sol

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1 - Exercise (6 points) Consider the network below, where links are fiber-optics cables. At time t=0, hosts A, D, F start sending the following sequences of packets (one immediately after the other): From A, with destinations: B, B, C, B and packet size 1500 kbyte- From D, with destination: C and packet size 2000 kbyte- From F, with destinations: B, B and packet size 1000 kbyte- All the nodes R1, R2 and R3 operate in the store-and-forward mode, with FIFO queues. Using a time diagrams, compute the arrival time of each packet to destination. 24/06/2019 domenica 23 giugno 2019 23:48 FCN 2018-19 Pagina 1 2 - Exercise (6 points) Consider the network below, in which the cost of each link is reported near the link. Apply the Dijkstra algorithm to compute the shortest-path tree form node It to all the other nodes. Draw the tree on the right of the map and fill in the routing table of It node below 1- Consider the shortest path between node It and node Uk computed in the previous step. Compute the second shortest path between the same nodes which is link-disjoint with the first (write the sequence of nodes and the cost of the path). Then compute the third shortest path link-disjoint with the second and the first and so on, until possible. 2- How many different disjoint paths connect the two nodes Uk and It? How many link failures can be recovered in the worst-case scenario? 3- It Dest. Next hop Cost Pt Sp Fr Uk Ge Ck Gr Pl Ur Sw FCN 2018-19 Pagina 2 3 - Exercise (6 points) Consider a file transfer from host A to host B over a TCP connection. The size of the file is B = 37.5 kbyte. Given the following assumptions: Segment and ACK transmission time is negligible All segments allowed by the send window are instantaneously sent by the transmitter; processing time in the receiver…