Interactive end-of-chapter exercises


IPv6 Tunneling and Encapsulation

Consider the network shown below which contains four IPv6 subnets, connected by a mix of IPv6-only routers(shaded blue), IPv4-only routers (shaded red) and dual-capable IPv6/IPv4 routers (shaded blue with red interfaces to IPv4 routers). You might want to review Section 4.3.4 in the textbook before doing this problem.


Suppose that a host of subnet D wants to send an IPv6 datagram to a host on subnet A. Assume that the forwarding between these two hosts goes along the path: D --> E --> d --> c --> B --> A



Question List


1. Is the datagram being forwarded from D to E an IPv4 or IPv6 datagram?

2. What is the source address of this D to E datagram?

3. What is the destination address of this D to E datagram?

4. Is this D to E datagram encapsulating another datagram? Yes or No.

5. Is the datagram being forwarded from E to d an IPv4 or IPv6 datagram?

6. What is the source address of this E to d datagram?

7. What is the destination address of this E to d datagram?

8. Is this E to d datagram encapsulating another datagram? Yes or No.

9. What is the source address of this encapsulated datagram?

10. What is the destination address of this encapsulated datagram?

11. Is the datagram being forwarded from d to c an IPv4 or IPv6 datagram?

12. What is the source address of this d to c datagram?

13. What is the destination address of this d to c datagram?

14. Is this d to c datagram encapsulating another datagram? Yes or No.

15. What is the source address of this encapsulated datagram?

16. What is the destination address of this encapsulated datagram?

17. Is the datagram being forwarded from c to B an IPv4 or IPv6 datagram?

18. What is the source address of this c to B datagram?

19. What is the destination address of this c to B datagram?

20. Is this c to B datagram encapsulating another datagram? Yes or No.

21. What is the source address of this encapsulated datagram?

22. What is the destination address of this encapsulated datagram?

23. Is the datagram being forwarded from B to A an IPv4 or IPv6 datagram?

24. What is the source address of this B to A datagram?

25. What is the destination address of this B to A datagram?

26. Is this B to A datagram encapsulating another datagram? Yes or No.

27. What router is the 'tunnel entrance'? Give the router's letter

28. What router is the 'tunnel exit'? Give the router's letter

29. Which protocol encapsulates the other, IPv4 or IPv6?




Solution


1. The datagram is an IPv6 datagram.

2. The source IP address is 9C51:D4BC:D556:9FEA:4A8C:A826:D3B2:1CB1

3. The destination IP address is 6A82:ADD6:DF7D:57B2:D568:BACF:7D58:2A9B

4. No, the datagram is NOT encapsulated.

5. The datagram is an IPv4 datagram.

6. The source IP address is 70.88.45.146

7. The destination IP address is 109.250.219.207

8. Yes, the datagram is encapsulated.

9. The source address of this encapsulated datagram is 9C51:D4BC:D556:9FEA:4A8C:A826:D3B2:1CB1

10. The destination address of this encapsulated datagram is 6A82:ADD6:DF7D:57B2:D568:BACF:7D58:2A9B

11. The datagram is an IPv4 datagram.

12. The source IP address is 70.88.45.146

13. The destination IP address is 109.250.219.207

14. Yes, the datagram is encapsulated.

15. The source address of this encapsulated datagram is 9C51:D4BC:D556:9FEA:4A8C:A826:D3B2:1CB1

16. The destination address of this encapsulated datagram is 6A82:ADD6:DF7D:57B2:D568:BACF:7D58:2A9B

17. The datagram is an IPv4 datagram.

18. The source IP address is 70.88.45.146

19. The destination IP address is 109.250.219.207

20. Yes, the datagram is encapsulated.

21. The source address of this encapsulated datagram is 9C51:D4BC:D556:9FEA:4A8C:A826:D3B2:1CB1

22. The destination address of this encapsulated datagram is 6A82:ADD6:DF7D:57B2:D568:BACF:7D58:2A9B

23. The datagram is an IPv6 datagram.

24. The source IP address is 9C51:D4BC:D556:9FEA:4A8C:A826:D3B2:1CB1

25. The destination IP address is 6A82:ADD6:DF7D:57B2:D568:BACF:7D58:2A9B

26. No, the datagram is NOT encapsulated.

27. The tunnel entrance is router E

28. The tunnel exit is router B

29. IPv4, in order to maintain compatibility with existing IPv4 infrastructure, IPv6 datagrams are put in the payload of an IPv4 datagram. These IPv4 datagrams are passed on until it reaches a router which supports IPv6, where the IPv6 datagram is decapsulated and passed on.



That's incorrect

That's correct

The answer was: IPv6

Question 1 of 29

The answer was: 9C51:D4BC:D556:9FEA:4A8C:A826:D3B2:1CB1

Question 2 of 29

The answer was: 6A82:ADD6:DF7D:57B2:D568:BACF:7D58:2A9B

Question 3 of 29

The answer was: No

Question 4 of 29

The answer was: IPv4

Question 5 of 29

The answer was: 70.88.45.146

Question 6 of 29

The answer was: 109.250.219.207

Question 7 of 29

The answer was: Yes

Question 8 of 29

The answer was: 9C51:D4BC:D556:9FEA:4A8C:A826:D3B2:1CB1

Question 9 of 29

The answer was: 6A82:ADD6:DF7D:57B2:D568:BACF:7D58:2A9B

Question 10 of 29

The answer was: IPv4

Question 11 of 29

The answer was: 70.88.45.146

Question 12 of 29

The answer was: 109.250.219.207

Question 13 of 29

The answer was: Yes

Question 14 of 29

The answer was: 9C51:D4BC:D556:9FEA:4A8C:A826:D3B2:1CB1

Question 15 of 29

The answer was: 6A82:ADD6:DF7D:57B2:D568:BACF:7D58:2A9B

Question 16 of 29

The answer was: IPv4

Question 17 of 29

The answer was: 70.88.45.146

Question 18 of 29

The answer was: 109.250.219.207

Question 19 of 29

The answer was: Yes

Question 20 of 29

The answer was: 9C51:D4BC:D556:9FEA:4A8C:A826:D3B2:1CB1

Question 21 of 29

The answer was: 6A82:ADD6:DF7D:57B2:D568:BACF:7D58:2A9B

Question 22 of 29

The answer was: IPv6

Question 23 of 29

The answer was: 9C51:D4BC:D556:9FEA:4A8C:A826:D3B2:1CB1

Question 24 of 29

The answer was: 6A82:ADD6:DF7D:57B2:D568:BACF:7D58:2A9B

Question 25 of 29

The answer was: No

Question 26 of 29

The answer was: E

Question 27 of 29

The answer was: B

Question 28 of 29

The answer was: IPv4

Question 29 of 29

Try Another Problem

We greatly appreciate the work of John Broderick (UMass '21) in helping to develop these interactive problems.

Copyright © 2010-2025 J.F. Kurose, K.W. Ross
Comments welcome and appreciated: kurose@cs.umass.edu