Interactive end-of-chapter exercises


Supplement to Computer Networking: A Top Down Approach 8th Edition


"Tell me and I forget. Show me and I remember. Involve me and I understand." Chinese proverb

Textbook Cover

Learning Switches - Basic

Consider the LAN below consisting of 10 computers connected by two self-learning Ethernet switches. (You may want to re-read section 6.4.3 in the text). At t=0 the switch table entries for both switches are empty. At t = 1, 2, 3, and 4, a source ends to a destination as shown below, and the destination replies immediately (well before the next time step).

Assume that the following connections occur:

   t=1: E -> D
   t=2: L -> G
   t=3: C -> A
   t=4: K -> C

Fill out the two switch tables and answer the questions below.



Question List


1. At t=1, what is the source entry for switch 1? Format your answer as letter,number or 'n/a'

2. At t=1, what is the destination entry for switch 1? Format your answer as letter,number or 'n/a'

3. At t=1, what is the source entry for switch 2? Format your answer as letter,number or 'n/a'

4. At t=1, what is the destination entry for switch 2? Format your answer as letter,number or 'n/a'

5. At t=2, what is the source entry for switch 1? Format your answer as letter,number or 'n/a'

6. At t=2, what is the destination entry for switch 1? Format your answer as letter,number or 'n/a'

7. At t=2, what is the source entry for switch 2? Format your answer as letter,number or 'n/a'

8. At t=2, what is the destination entry for switch 2? Format your answer as letter,number or 'n/a'

9. At t=3, what is the source entry for switch 1? Format your answer as letter,number or 'n/a'

10. At t=3, what is the destination entry for switch 1? Format your answer as letter,number or 'n/a'

11. At t=3, what is the source entry for switch 2? Format your answer as letter,number or 'n/a'

12. At t=3, what is the destination entry for switch 2? Format your answer as letter,number or 'n/a'

13. At t=4, what is the source entry for switch 1? Format your answer as letter,number or 'n/a'

14. At t=4, what is the destination entry for switch 1? Format your answer as letter,number or 'n/a'

15. At t=4, what is the source entry for switch 2? Format your answer as letter,number or 'n/a'

16. At t=4, what is the destination entry for switch 2? Format your answer as letter,number or 'n/a'




Solution


1. At time t=1, (E,5) is added as an entry to switch table 1.

2. At time t=1, (D,4) is added as an entry to switch table 1.

3. At time t=1, (E,8) is added as an entry to switch table 2.

4. At time t=1, switch table 2 doesn't observe this frame

5. At time t=2, (L,7) is added as an entry to switch table 1.

6. At time t=2, switch table 1 doesn't observe this frame

7. At time t=2, (L,15) is added as an entry to switch table 2.

8. At time t=2, (G,10) is added as an entry to switch table 2.

9. At time t=3, (C,3) is added as an entry to switch table 1.

10. At time t=3, (A,1) is added as an entry to switch table 1.

11. At time t=3, (C,8) is added as an entry to switch table 2.

12. At time t=3, switch table 2 doesn't observe this frame

13. At time t=4, (K,7) is added as an entry to switch table 1.

14. At time t=4, since the entry for computer C in switch table 1 already exists, no new table entry is made

15. At time t=4, (K,14) is added as an entry to switch table 2.

16. At time t=4, since the entry for computer C in switch table 2 already exists, no new table entry is made



That's incorrect

That's correct

The answer was: E,5

Question 1 of 16

The answer was: D,4

Question 2 of 16

The answer was: E,8

Question 3 of 16

The answer was: n/a

Question 4 of 16

The answer was: L,7

Question 5 of 16

The answer was: n/a

Question 6 of 16

The answer was: L,15

Question 7 of 16

The answer was: G,10

Question 8 of 16

The answer was: C,3

Question 9 of 16

The answer was: A,1

Question 10 of 16

The answer was: C,8

Question 11 of 16

The answer was: n/a

Question 12 of 16

The answer was: K,7

Question 13 of 16

The answer was: exists

Question 14 of 16

The answer was: K,14

Question 15 of 16

The answer was: exists

Question 16 of 16

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