CS158a Spring 2009Practice Final

To study for the final I would suggest you: (1) Know how to do (by heart) all the practice problems. (2) Go over your notes at least three times. Second and third time try to see how much you can remember from the first time. (3) Go over what you did on the HW sets. (4) Try to create your own problems similar to the ones I have given and solve them. (5) Skim the relevant sections from the book. (6) If you want to study in groups, at this point you are ready to quiz each other. The practice midterm is below. Here are some facts about the actual final: (a) It is closed book, closed notes. Nothing will be permitted on your desk except your pen (pencil) and test. (b) You should bring photo ID. (c) There will be more than one version of the test. Each version will be of comparable difficulty. (d) The final is ten problems and is comprehensive. There will be four problems containing material from before the midterm; six problems containing material after the midterm. (e) One problem (less typos) on the actual test will be from the practice final; one problem (less typos) will be from the practice midterm.

1. What is the 8 bit virtual path identifier in ATM used for? Explain its relationship with the 16 bit virtual circuit identifier.
2. Briefly describe each of the following kinds of switch fabrics: (a) shared bus, (b) shared memory, (c) cross-bar, and (d) batcher-banyan networks.
3. What is an IP tunnel? How could a VPN be built using such tunnels?
4. What does reliable flooding mean? What are the major components of a link-state packet? How are these packets used to construct a forwarding table?
5. In what context is proxy ARP used? Briefly describe how it works.
6. What is DHCP? How is the analogous process handled in IPv6?
7. Describe the process by which a host can multicast to a group (a) if PIM-SM is being used; (b) if DVRMP is being used.
8. Describe the process by which connections are established in TCP.
9. What is the problem with only having 32 bits for sequence numbers in TCP. Explain how options headers are used to solve this problem.
10. Distinguish between the following kinds of resource allocation strategies: (a) router-centric versus host centric. (b) reservation based versus feedback-based. (c) window-based versus rate-based.