Exercise 8.1.
Explain which is the simplest change that could be made to the standard of an Ethernet 10BaseT network in order to be able to deploy two stations at a maximum distance of 10 km.

Exercise 8.6.
Determine the maximum throughput achievable with the Fast Ethernet structure with two-level topology shown in Figure 8.6 in which the three network devices are all switches instead of hubs. Compare the result obtained with what would be obtained if all the terminals were interfaced to a single switch.

Figure 8.6 Multilevel Ethernet configuration (Exercise 8.6).

Exercise 8.10.
Calculate the maximum efficiency that characterizes the IEEE 802.11b access protocol taking into account only the MAC layer and physical layer (PL) overhead, knowing that the latter defines 144 or 72 preamble bits, depending on the modulation type, and 6 bytes of headers, neglecting the times required to send control frames and the propagation times.

Exercise 8.12.
A network configuration is given which includes 5 bridges (, , , , ) and 5 LANs (A, B, C, D, E) with the following connections: bridge connected to networks A (port 1), B (port 2), C (port 3), bridge connected to networks C (port 1), E (port 2), D (port 3), bridge B3 connected to networks D (port 1), E (port 2), bridge B4 connected to networks C (port 1), E (port 2), bridge connected to networks B (port 1), E (port 2). Apply the spanning tree protocol procedure to obtain the status of all the ports of the bridges whose BI is equal to the respective numerical index, assuming unit cost of crossing each of the networks

Exercise 8.15.
A network configuration is given which includes 5 bridges and 5 LANs (A, B, C, D, E) with the following connections: bridge connected to networks A (port 1), C (port 2), bridge connected to networks B (port 1), D (port 2), bridge connected to networks A (port 1), B (port 2), E (port 3), bridge connected to networks C (port 1), E (port 2), bridge connected to networks D (port 1), E (port 2). Apply the procedure of the spanning tree protocol to obtain the status of all the ports of the bridges whose BI is equal to the respective numerical index, assuming unit cost of crossing each of the networks.

Exercise 8.19.
Consider the network configuration with spanning tree shown in Figure 8.31 where 10 hosts are interfaced. It is assumed that all forwarding tables are initially empty and that only 9 frames have been successfully transmitted with the following source-destination pairs (SA-DA): Q-S, R-X, S-R, T-V, V-Y, WU, X-W, Y-R, Z-X, as already described in Exercise 8.17. Now consider the displacement of the stations R, T, U which are connected to the networks D, A and B, respectively. Determine the new content of the forwarding tables of bridges , and after the successful transfer of the 3 frames with the following source-destination addresses: R-Z, T-V, S-U.

Figure 8.31 Ethernet networks interconnected by bridges according to Example 8.7 (Exercise 8.19).