7. The figure below shows a small Ethernet LAN. Answer the following questions. (a) What kind of network topology is used? (b) Assume stations are connected through a switch and interfaces operate in half-duplex mode. Station D sends a frame to the server while Station A sends a frame to Station D. Is there any frame collision? (c) Repeat the previous question if interfaces operate in full-duplex mode. (d) Show one situation where a collision could happen with stations connected through a switch and full-duplex ports. ! Server