Section I: [36 pts] Short Answer Questions
Question 1 [9pts]: In reliable data transmission, an important component is the timer, which is used to estimate the time that a packet is lost. Setting timeout value is important as it cannot be too long or too short. Specify how TCP set its timeout value.
Question 2: [7pts] How does a host get an IP address? How does an organization/network get its IP addresses?
Question 3: [4pts] What is hot-potato routing?
Question 4: [10pts] What is Multiple Access Protocol? Describe three broad classes of Multiple
Access Protocols.
Question 5: [6pts] Specify the motivation of Manchester Encoding and how it works.
Section II: [44 pts] Long Answer Questions
Question 6: [8pts] Consider the queuing delay in a router buffer. Suppose all packets are L bits, the transmission rate is R bps, and that N packets simultaneously arrive at the buffer
LN
every R seconds. Find the average queuing delay of a packet.
Question 7: [12 pts] Show the forwarding table of node w. It uses Link-State algorithm for the forwarding table computation. Illustrate each step of your derivation of this forwarding table.
z
12
6 x
y
1
5
7
3
w3
t 4
1
2
v 3
4 6u4
s
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Question 8: [12pts]
Consider the following network and answer the following questions.
A
B
a. How many subnets are there?
b. Assign IP addresses to all the interfaces. For subnet 1, you can use 111.111.111.xxx, for subnet 2, you can use 122.222.222.xxx and so forth.
c. Assign MAC address to all the adapters that you can find.
d. Consider sending an IP datagram from Host A to Server B. Suppose all the ARP tables are up to date. Enumerate all the steps (including both network layer and data link layer activities). e. Reconsider (d), but now assuming that the ARP table in the sending host is empty. Enumerate all the steps (including both network layer and data link layer activities).
Question 9 [12 pts] Suppose three active nodes A, B, and C are competing for access to a channel using slotted ALOHA. Assume each node has an infinite number of packets to send. Each node attempts to transmit in each slot with probability p. The first slot is numbered as slot 1, the second slot is numbered as slot 2, and so on.
a. What is the probability that node A succeeds for the first time in slot 4?
b. What is the probability that some node succeed in slot 2?
c. What is the probability that the first success occurs in slot 4?
d. What is the efficiency of this three-node system?
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