UTD-CS 6390.502 Advanced Computer Networks-Spring 2002-Exam I

Name:___________________________

Notes: Answer any subset of the 8 questions so that the sum of points of the questions you answer does not exceed 75. if you exceed 75 points, I will arbitrary choose which of your questions to grade (and the sum is not guaranteed to be 75).

1. (8 points) Consider the following network. Show the complete forwarding table maintained by router R5. (The small i’s such as i1, i2, …i11 etc., are interfaces with hardware addresses h1, h2, …, h11 respectively.) (Hosts on the networks are not shown in the figure.)

	R6

2. (7 points) Bridges and routers are used to interconnect networks. When do you use routers and when do you use bridges?

3. (15 points) Consider the topology given in the following figure: Link state routing protocol is used to compute forwarding tables. Show the contents of all LSP’s (Link State Packets) received by nodes A and E. Also, show the contents of the forwarding table at nodes A and E and the sequence of steps executed (in high level) by A and E in constructing the forwarding table.

4. (8 points) What is flow control and how is it achieved/implemented in TCP?

5. (7 points) An application needs to send digitized voice packets to a distant host over a transport protocol. Which of the three transport protocols, TCP, SCTP, or UDP is suitable and why?

6. (15 points) Explain, with an example, how head-of-line blocking is avoided in SCTP.

7. (15 points) What are the essential features of DiffServ? What part of IP header is used to implement it? What changes are needed at the router to make it conform to DiffServ.

8. (15 points) How would you hot-enable SCTP associations (similar to hot-enabling TCP connections)? Give a high level architecture of your approach.