Question

1.  

(a)

1. We are sending a 30 Mbit MP3 file from a source host to a destination host. All links in the path between source and destination have a transmission rate of 10 Mbps. Assume that the propagation speed is 2*10⁸ meters/sec, and the distance between source and destination is 10,000 km. Now suppose that the MP3 file is broken into 3 packets, each of 10 Mbits. Ignore headers that may be added to these packets. Also ignore router processing delays. Assuming store and forward packet switching at the router, the total delay is ____.

	A.	6.05 seconds
	B.	4.05 seconds
	C.	3.05 seconds
	D.	none of the above

(b) Review the car-caravan example in Section 1.4. Again assume a propagation speed of 100 km/hour. Suppose the caravan travels 200 km, beginning in front of one tollbooth, passing through a second tollbooth, and finishing just before a third tollbooth. Now suppose that when a car arrives at the second tollbooth, it proceeds through the tollbooth without waiting for the cars behind it. What is the end-to-end delay?

	A.	62 minutes
	B.	124 minutes
	C.	122 minutes and 12 seconds
	D.	122 minutes and 24 seconds

(c) We are sending a 30 Mbit MP3 file from a source host to a destination host. All links in the path between source and destination have a transmission rate of 10 Mbps. Assume that the propagation speed is 2*10⁸ meters/sec, and the distance between source and destination is 10,000 km. Now suppose there is only one link between source and destination, and there are 10 FDM channels in the link. The MP3 file is sent over one of the channels. The end-to-end delay is ____.

	A.	30.05 seconds
	B.	300 microseconds
	C.	3 seconds
	D.	none of the above

(d) We are sending a 30 Mbit MP3 file from a source host to a destination host. All links in the path between source and destination have a transmission rate of 10 Mbps. Assume that the propagation speed is 2*10⁸ meters/sec, and the distance between source and destination is 10,000 km. Now suppose there is only one link between source and destination. Also suppose that the entire MP3 file is sent as one packet. The transmission delay is ____.

	A.	3 seconds
	B.	3.05 seconds
	C.	50 milliseconds
	D.	none of the above

Answer 1

1. We are sending a 30 Mbit MP3 file from a source host to a destination host. All links in the path between source and destination have a transmission rate of 10 Mbps. Assume that the propagation speed is 2*10⁸ meters/sec, and the distance between source and destination is 10,000 km. Now suppose that the MP3 file is broken into 3 packets, each of 10 Mbits. Ignore headers that may be added to these packets. Also ignore router processing delays. Assuming store and forward packet switching at the router, the total delay is 4.05 seconds
2. Review the car-caravan example in Section 1.4. Again assume a propagation speed of 100 km/hour. Suppose the caravan travels 200 km, beginning in front of one tollbooth, passing through a second tollbooth, and finishing just before a third tollbooth. Now suppose that when a car arrives at the second tollbooth, it proceeds through the tollbooth without waiting for the cars behind it. The end delay is 124 minutes.
3. We are sending a 30 Mbit MP3 file from a source host to a destination host. All links in the path between source and destination have a transmission rate of 10 Mbps. Assume that the propagation speed is 2*10⁸ meters/sec, and the distance between source and destination is 10,000 km. Now suppose there is only one link between source and destination, and there are 10 FDM channels in the link. The MP3 file is sent over one of the channels. The end-to-end delay is 30.05 seconds.
4. We are sending a 30 Mbit MP3 file from a source host to a destination host. All links in the path between source and destination have a transmission rate of 10 Mbps. Assume that the propagation speed is 2*10⁸ meters/sec, and the distance between source and destination is 10,000 km. Now suppose there is only one link between source and destination, and there are 10 FDM channels in the link. The MP3 file is sent over one of the channels. The end-to-end delay is 3 seconds.