Exercise 1.3.
It is requested to transfer an L byte file from Shannon in Ireland to New York in the United States. Assuming that the connection has a capacity C = 10 Gbit/s and is realized through a transatlantic fibre optic cable of length d = 5000 km, determine the file size so that when the first bit of the file reaches New York the last bit of the file is transmitted by Shannon.

Exercise 1.5.
With reference to the protocol stack of Figure 1.11, determine the portion of the overhead required to transport IUs through a network, assuming that the added header in the transport and network layers is respectively 20% and 5% of the payload carried by the IU, while the link layer adds a fixed header of 20 bytes.

Figure 1.11 Layered model and protocol stack (Exercise 1.5).

Exercise 1.9.
Two hosts connected to the Internet through their respective access ISPs interact thanks to the connectivity made available by two regional ISPs, one for each of the two regions where the hosts are located, and a Tier-1 ISP. Assuming that no more than two routers are crossed in each ISP, determine the number of times N_i (i = 1,…,5) in which the operations relating to each of the 5 protocol levels of the layered model are carried out (the application layer is conventionally referred to as number 5).