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 F wants to send an IPv6 datagram to a host on subnet B. Assume that the forwarding between these two hosts goes along the path: F --> b --> c --> B



Question List


1. Is the datagram being forwarded from F to b an IPv4 or IPv6 datagram?

2. What is the source address of this F to b datagram?

3. What is the destination address of this F to b datagram?

4. Is this F to b datagram encapsulating another datagram? Yes or No.

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

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

7. Is the datagram being forwarded from b to c an IPv4 or IPv6 datagram?

8. What is the source address of this b to c datagram?

9. What is the destination address of this b to c datagram?

10. Is this b to c datagram encapsulating another datagram? Yes or No.

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

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

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

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

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

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

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

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

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

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

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




Solution


1. The datagram is an IPv4 datagram.

2. The source IP address is 192.108.104.60

3. The destination IP address is 78.127.109.168

4. Yes, the datagram is encapsulated.

5. The source address of this encapsulated datagram is 6CE6:232B:4C39:5711:E117:DB39:DDBB:8E62

6. The destination address of this encapsulated datagram is B441:EFE3:DCB6:EC18:CA37:7D76:931E:1C6E

7. The datagram is an IPv4 datagram.

8. The source IP address is 192.108.104.60

9. The destination IP address is 78.127.109.168

10. Yes, the datagram is encapsulated.

11. The source address of this encapsulated datagram is 6CE6:232B:4C39:5711:E117:DB39:DDBB:8E62

12. The destination address of this encapsulated datagram is B441:EFE3:DCB6:EC18:CA37:7D76:931E:1C6E

13. The datagram is an IPv4 datagram.

14. The source IP address is 192.108.104.60

15. The destination IP address is 78.127.109.168

16. Yes, the datagram is encapsulated.

17. The source address of this encapsulated datagram is 6CE6:232B:4C39:5711:E117:DB39:DDBB:8E62

18. The destination address of this encapsulated datagram is B441:EFE3:DCB6:EC18:CA37:7D76:931E:1C6E

19. The tunnel entrance is router F

20. The tunnel exit is router B

21. 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: IPv4

Question 1 of 21

The answer was: 192.108.104.60

Question 2 of 21

The answer was: 78.127.109.168

Question 3 of 21

The answer was: Yes

Question 4 of 21

The answer was: 6CE6:232B:4C39:5711:E117:DB39:DDBB:8E62

Question 5 of 21

The answer was: B441:EFE3:DCB6:EC18:CA37:7D76:931E:1C6E

Question 6 of 21

The answer was: IPv4

Question 7 of 21

The answer was: 192.108.104.60

Question 8 of 21

The answer was: 78.127.109.168

Question 9 of 21

The answer was: Yes

Question 10 of 21

The answer was: 6CE6:232B:4C39:5711:E117:DB39:DDBB:8E62

Question 11 of 21

The answer was: B441:EFE3:DCB6:EC18:CA37:7D76:931E:1C6E

Question 12 of 21

The answer was: IPv4

Question 13 of 21

The answer was: 192.108.104.60

Question 14 of 21

The answer was: 78.127.109.168

Question 15 of 21

The answer was: Yes

Question 16 of 21

The answer was: 6CE6:232B:4C39:5711:E117:DB39:DDBB:8E62

Question 17 of 21

The answer was: B441:EFE3:DCB6:EC18:CA37:7D76:931E:1C6E

Question 18 of 21

The answer was: F

Question 19 of 21

The answer was: B

Question 20 of 21

The answer was: IPv4

Question 21 of 21

Try Another Problem

We gratefully acknowledge the programming and problem design work of John Broderick (UMass '21), which has really helped to substantially improve this site.

Copyright © 2010-2022 J.F. Kurose, K.W. Ross
Comments welcome and appreciated: kurose@cs.umass.edu