Soal

Oleh Azmi Afrian

30 tayangan

Transkrip Soal

24. The following is a dump of a TCP header in hexadecimal format.
05320017 0000 00011 00000000 5OO207FF 00000000
1

2

3

4

5

a. What is the source port number? 0532=(0x163)+(5x162)+(3x161)+(2x160)=1330
b. What is the destination port number?0017==(0x163)+(0x162)+(1x161)+(7x160) =23
(default TCP port)
c. What the sequence number? 000000011=17
d. What is the acknowledgment number? 0x00000000
e. What is the length of the header? 0x50
f. What is the type of the segment?
g. What is the window size?

25. To make the initial sequence number a random number, most systems start the counter
at 1 during bootstrap and increment the counter by 64,000 every 0.5 s. How long
does it take for the counter to wrap around?

26. In a connection, the value of cwnd is 3000 and the value of rwnd is 5000. The host has
sent 2000 bytes which has not been acknowledged. How many more bytes can be sent?
Window size= minimum (cwnd ,rwnd)
Window size = minimum (3000 , 5000)=3000
The number of bytes that can be sent = 3000 − 2000 = 1000 bytes

27. TCP opens a connection using an initial sequence number (ISN) of 14,534. The
other party opens the connection with an ISN of 21,732. Show the three TCP segments
during the connection establishment.

28. A client uses TCP to send data to a server. The data are 16 bytes. Calculate the efficiency
of this transmission at the TCP level (ratio of useful bytes to total bytes).
Calculate the efficiency of transmission at the IP level. Assume no options for the
IP header. Calculate the efficiency of transmission at the data link layer. Assume no
options for the IF header and use Ethernet at the data link layer.

29. TCP is sending data at 1 Mbyte/s. If the sequence number starts with 7000, how
long does it take before the sequence number goes back to zero?

30. A TCP connection is using a window size of 10,000 bytes, and the previous
acknowledgment number was 22,001. It receives a segment with acknowledgment
number 24,001 and window size advertisement of 12,000. Draw a diagram to show
the situation of the window before and after.

31. A window holds bytes 2001 to 5000. The next byte to be sent is 3001. Draw a figure
to show the situation of the window after the following two events.
a. An ACK segment with the acknowledgment number 2500 and window size

b. A segment carrying 1000 bytes is sent.

32. In SCTP, the value of the cumulative TSN in a SACK is 23. The value of the previous
cumulative TSN in the SACK was 29. What is the problem?

33. In SCTP, the state of a receiver is as follows:
a. The receiving queue has chunks 1 to 8, 11 to 14, and 16 to 20.
b. There are 1800 bytes of space in the queue.
SECTION 23.8 PRACTICE SET 759
c. The value of lastAck is 4.
d. No duplicate chunk has been received.
e. The value of cumTSN is 5.
Show the contents of the receiving queue and the variables.
34. In SCTP, the state of a sender is as follows:
a. The sending queue has chunks 18 to 23.
b. The value of cumTSN is 20.
c. The value of the window size is 2000 bytes.
d. The value of inTransit is 200.
If each data chunk contains 100 bytes of data, how many DATA chunks can be sent
now? What is the next DATA chunk to be sent?
Research Activities
36. TCP uses a transition state diagram to handle sending and receiving segments.
37. SCTP uses a transition state diagram to handle sending and receiving segments.

38. What is the half-open case in TCP?
39. What is the half-duplex close case in TCP?
40. The tcpdump command in UNIX or LINUX can be used to print the headers
of packets of a network interface. Use tcpdump to see the segments sent and received.
41. In SCTP, find out what happens if a SACK chunk is delayed or lost.
42. Find the name and functions of timers used in TCP.
43. Find the name and functions of timers used in SCTP.
44. Find out more about ECN in SCTP. Find the format of these two chunks.
45. Some application programs, such as FTP, need more than one connection when
using TCP. Find how the multistream service of SCTP can help these applications
establish only one association with several streams.

Judul: Soal

Oleh: Azmi Afrian

Ikuti kami