Observe the transmission of TCP segments and ACKs. How frequently does the receiver send ACKs? Is there an ACK sent for each TCP segment, or less often. Can you determine the rule used by TCP to send ACKs? Can you explain this rule?

What will be an ideal response?

The receiver sends ACKs at intervals less than 1ms. For most of the time, the receiver sends ACKs every other segment (Frame 6,7 and 8). The receiver sends one ACK after several segments (Frame 16,17,18,19,20,21,22,23 and 24) , or sends several ACKs (Frame 33,34,35,36,37 and 38). The ACKs are cumulative, not every TCP segment has a corresponding ACK. Sending ACKs this way helps in reducing the number of interrupts seen by the sender, reduces the ACKs in the network, and also gives opportunity to the receiver to piggyback the ACK on a data segment.
```
No. Time Source Destination Protocol Info
1 0.000000 10.0.5.11 Broadcast ARP Who has

10.0.5.22? Tell 10.0.5.11

2 0.000256 10.0.5.22 10.0.5.11 ARP 10.0.5.22 is at

00:06:5b:4b:e1:da

3 0.000280 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[SYN] Seq=339274348 Ack=0 Win=5840 Len=0

4 0.000565 10.0.5.22 10.0.5.11 TCP 4444 > 3117

[SYN, ACK] Seq=305997827 Ack=339274349 Win=5792 Len=0

5 0.000627 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[ACK] Seq=339274349 Ack=305997828 Win=5840 Len=0

6 0.001151 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[PSH, ACK] Seq=339274349 Ack=305997828 Win=5840 Len=1000

7 0.001304 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[PSH, ACK] Seq=339275349 Ack=305997828 Win=5840 Len=1000

8 0.003011 10.0.5.22 10.0.5.11 TCP 4444 > 3117

[ACK] Seq=305997828 Ack=339275349 Win=7000 Len=0

9 0.003058 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[ACK] Seq=339276349 Ack=305997828 Win=5840 Len=1448

10 0.003068 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[ACK] Seq=339277797 Ack=305997828 Win=5840 Len=1448

11 0.004420 10.0.5.22 10.0.5.11 TCP 4444 > 3117

[ACK] Seq=305997828 Ack=339276349 Win=9000 Len=0

12 0.004473 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[ACK] Seq=339279245 Ack=305997828 Win=5840 Len=1448

13 0.004482 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[ACK] Seq=339280693 Ack=305997828 Win=5840 Len=1448

14 0.008337 10.0.5.22 10.0.5.11 TCP 4444 > 3117

[ACK] Seq=305997828 Ack=339277797 Win=11584 Len=0

15 0.008416 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[ACK] Seq=339282141 Ack=305997828 Win=5840 Len=1448

16 0.008427 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[ACK] Seq=339283589 Ack=305997828 Win=5840 Len=1448

17 0.008407 10.0.5.22 10.0.5.11 TCP 4444 > 3117

[ACK] Seq=305997828 Ack=339279245 Win=14480 Len=0

18 0.008446 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[PSH, ACK] Seq=339285037 Ack=305997828 Win=5840 Len=1448

19 0.008491 10.0.5.22 10.0.5.11 TCP 4444 > 3117

[ACK] Seq=305997828 Ack=339280693 Win=17376 Len=0

20 0.008576 10.0.5.22 10.0.5.11 TCP 4444 > 3117

[ACK] Seq=305997828 Ack=339282141 Win=20272 Len=0

21 0.008936 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[PSH, ACK] Seq=339286485 Ack=305997828 Win=5840 Len=864

22 0.009003 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[PSH, ACK] Seq=339287349 Ack=305997828 Win=5840 Len=1000

23 0.009054 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[PSH, ACK] Seq=339288349 Ack=305997828 Win=5840 Len=1000

24 0.015096 10.0.5.22 10.0.5.11 TCP 4444 > 3117

[ACK] Seq=305997828 Ack=339283589 Win=23168 Len=0

25 0.015182 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[ACK] Seq=339289349 Ack=305997828 Win=5840 Len=1448

26 0.015193 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[ACK] Seq=339290797 Ack=305997828 Win=5840 Len=1448

27 0.015159 10.0.5.22 10.0.5.11 TCP 4444 > 3117

[ACK] Seq=305997828 Ack=339285037 Win=26064 Len=0

28 0.015212 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[ACK] Seq=339292245 Ack=305997828 Win=5840 Len=1448

29 0.015264 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[ACK] Seq=339293693 Ack=305997828 Win=5840 Len=1448
30 0.015259 10.0.5.22 10.0.5.11 TCP 4444 > 3117

[ACK] Seq=305997828 Ack=339286485 Win=28960 Len=0

31 0.015276 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[ACK] Seq=339295141 Ack=305997828 Win=5840 Len=1448

32 0.015283 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[PSH, ACK] Seq=339296589 Ack=305997828 Win=5840 Len=1448

33 0.022890 10.0.5.22 10.0.5.11 TCP 4444 > 3117

[ACK] Seq=305997828 Ack=339287349 Win=31856 Len=0

34 0.022961 10.0.5.22 10.0.5.11 TCP 4444 > 3117

[ACK] Seq=305997828 Ack=339288349 Win=31856 Len=0

35 0.023030 10.0.5.22 10.0.5.11 TCP 4444 > 3117

[ACK] Seq=305997828 Ack=339289349 Win=32000 Len=0

36 0.023103 10.0.5.22 10.0.5.11 TCP 4444 > 3117

[ACK] Seq=305997828 Ack=339290797 Win=34752 Len=0

37 0.023178 10.0.5.22 10.0.5.11 TCP 4444 > 3117

[ACK] Seq=305997828 Ack=339292245 Win=37648 Len=0

38 0.023248 10.0.5.22 10.0.5.11 TCP 4444 > 3117

[ACK] Seq=305997828 Ack=339293693 Win=40544 Len=0

39 0.023271 10.0.5.11 10.0.5.22 TCP 3117 > 4444

[PSH, ACK] Seq=339298037 Ack=305997828 Win=5840 Len=312
```