1. What are the five layers in the Internet protocol stack? What are the principal responsibilities of each of these layers?

2. Explain the concept of encapsulation in networking discipline?

3. True or False ?

- Host breaks applications messages into packets.

TCP/IP protocol stacks describes the Internet structure.

The upper three layers of the OSI layering model correspond to the top layer in the TCP/IP model.

Network layer is commonly named IP layer.

Communication between two hosts starts from the physical layer.

Different application protocols needed for different physical links

4. Consider sending a packet from a source host to a destination host over a fixed route. List the delay components in the end-to-end delay Which of these delays are constant and which are variable?

5. Describe the Store-and-forward concept in packet switching network. To what type of delays it contributes?

6. A packet of length 1,500 bytes propagates over a link of distance 3,000 km, propagation speed 3.0x108 m/s, and transmission rate 2 Mbps

- Calculate the propagation delay.

- Calculate the transmission delay

- What is the total delay (ignoring other delay components)?

- If the packet was 10,000 bytes, would this change the propagation delay?

7. Suppose Host A wants to send a large file to Host B. The path from Host A to Host B has three links, of rates R1=700 kbps, R2=1 Mbps, and R3=1.5 Mbps

- Assuming no other traffic in the network, what is the throughput for the file transfer?

- Suppose the file is 4 million bytes. Dividing the file size by the throughput, roughly how long will it take to transfer the file to Host B?

- Repeat (a) and (b), but now with R2 reduced to 100 kbps

8. Suppose users share a 20 Mbps link. Also suppose each user requires 2 Mbps when transmitting, but each user transmits only 20 percent of the time

- When circuit switching is used, how many users can be supported?

- If there are 30 users: Can this many users be supported under circuit-switching? Yes or No. Can they be supported under packet-switching?

- For the remainder of this problem, suppose packet switching is used. Find the probability p that a given user is transmitting

- Suppose there are 30 users. Find the probability that at any given time, exactly 10 users (i.e., P(X=x)) are transmitting simultaneously. Use a binomial calculator (such as these BinCal I or BinCal II)

- Find the probability that there are 10 or more users transmitting simultaneously. (P(X>=x))

- Find the probability that there are 20 or more users transmitting simultaneously. (P(X>=x))

9. What is the difference between a virus and a worm?

10. Describe what is meant by access networks.

- What are the different types of links (physical media) used in access network? Name some technologies

11. Performance: In packet switching transmission over the network, we mention some factors that affect the performance of the packets: loss, delay, throughput. Briefly, describe their impact from your perspective as a user?

12. Network Core switching: Fill in the table below to compare between the two types of switching technologies used in the network core?

Criteria Circuit switching Packet switching

Reservation needed

Users share the same resources

Transmission speed per user compared to full link rate

Number of users supported Guaranteed delivery (i.e., no loss)

13. Describe the structure of todays Internet? Hint: ISPs of different tiers content provider networks access networks interconnection points