The following figure shows a TCP transaction. Assume Host A always has data to send, and each packet has size 20 Bytes. Assume Host A has a sending window of 40 Bytes, that is, it can send two "in-flight" packets maximum. Answer the following questions. A. At the time marked "1", i.e., when the first packet times out, will Host A send any packet? if your answer is no, explain why not; if your answer is yes, how many packets will be sent, what are the sequence numbers of them? B. At the time marked "2", i.e., when the ACK of the 2nd packet is received by Host A, will Host A send any packet? if your answer is no, explain why not; if your answer is yes, how many packets will be sent, what are the sequence numbers of them? Host A Host B Seq=80, 20 bytes of data Seq=100, 20 bytes of data timeout -

The following figure shows a TCP transaction. Assume Host A always has data to send, and each packet has size 20 Bytes. Assume Host A has a sending window of 40 Bytes, that is, it can send two "in-flight" packets maximum. Answer the following questions. A. At the time marked "1", i.e., when the first packet times out, will Host A send any packet? if your answer is no, explain why not; if your answer is yes, how many packets will be sent, what are the sequence numbers of them? B. At the time marked "2", i.e., when the ACK of the 2nd packet is received by Host A, will Host A send any packet? if your answer is no, explain why not; if your answer is yes, how many packets will be sent, what are the sequence numbers of them? Host A Host B Seq=80, 20 bytes of data Seq=100, 20 bytes of data timeout -

Principles of Information Security (MindTap Course List)

6th Edition

ISBN:9781337102063

Author:Michael E. Whitman, Herbert J. Mattord

Publisher:Michael E. Whitman, Herbert J. Mattord

Chapter6: Security Technology: Access Controls, Firewalls, And Vpns

Section: Chapter Questions

Problem 2RQ

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Q1.Suppose a client, say C, has established a TCP connection with a server, say S. After establishing the connection, the sender sends two TCP messages with data back-to-back ( the first TCP message with sequence number 32 and the second TCP message with sequence number 100). a. What is the sequence number chosen by the client? What could be the reason for choosing this value of sequence number?b. What is the data size of first and second TCP data messages?c. Suppose the server receives the first and second TCP messages with data with the difference of 100 milliseconds delay. What could be the ACK number for both the TCP data messages from the server side as per the TCP RFC.
Consider a client connecting to a web server via a router as shown in Fig.Q2. Client A sends a request to the server to retrieve a 7.5 Mbytes file. Given that the segment size is 50 Kbytes, the round trip time (RTT) between the server and client is 10 ms, the initial slow-start threshold is 16 and the client's buffer always has a storage space of 1 Mbytes. Assume that TCP Reno is used, there is no loss during transmission and the headers of protocols are ignored. 400 Mbps 200 Mbps 400 Mbps Link a Link b Link c Client Web Server Fig.Q2 (a) Describe how the value of sending window changes as a function of time (in units of RTT) during the whole connection time. 2.
P27. Host A and B are communicating over a TCP connection, and Host B has already received from A all bytes up through byte 126. Suppose Host A then sends two segments to Host B back-to-back. The first and second segments contain 80 and 40 bytes of data, respectively. In the first segment, the sequence number is 127, the source port number is 302, and the destination port number is 80. Host B sends an acknowledgment whenever it receives a segment from Host A. In the second segment sent from Host A to B, what are the sequence number, source port number, and destination port number? If the first segment arrives before the second segment, in the acknowledgment of the first arriving segment, what is the acknowledgment number, the source port number, and the destination port number? If the second segment arrives before the first segment, in the acknowledgment of the first arriving segment, what is the acknowledgment number? Suppose the two segments sent by A arrive in order at B.…
An HTTP client opens a TCP connection using an initial sequence number (ISN) of 14,534 and the ephemeral port number of 59,100. The server opens the connection with an ISN of 21,732. Show the three TCP segments during the connection establishment if the client defines the rwnd of 4000 and the server defines the rwnd of 5000. Ignore the calculation of the checksum field.
Host A and B are communicating over a TCP connection. Host B has already received from Host A all bytes up through byte 23. Suppose Host A then sends two segments to Host B back-to-back. The first and the second segments contain 30 and 50 bytes of data, respectively. In the first segment, the sequence number is 24, the source port number is 3000, and the destination port number is 80. Host B sends an acknowledgment whenever it receives a segment from Host A. A. In the second segment sent from Host A to B, what arethe sequence number_________,source port number __________,and destination port number__________?B. If the second segment arrives after the first segment, in the acknowledgment of the second segment, what arethe acknowledgment number___________,the source port number__________,and the destination port number __________?C. If the second segment arrives before the first segment, in the acknowledgment of the first arriving segment,what is the acknowledgment number ___________?D.…
TCP congestion control example. Consider the figure below, where a TCP sender sends 8 TCP segments at t = 1, 2, 3, 4, 5, 6, 7, 8. Suppose the initial value of the sequence number is 0 and every segment sent to the receiver each contains 100 bytes. The delay between the sender and receiver is 5 time units, and so the first segment arrives at the receiver at t = 6. The ACKs sent by the receiver at t = 6, 7, 8, 10, 11, 12 are shown. The TCP segments (if any) sent by the sender at t = 11, 13, 15, 16, 17, 18 are not shown. The segment sent at t=4 is lost, as is the ACK segment sent at t=7. TCP sender t=1 T t=2 t=3 t=4+ t=5- t=6+ t=11 t=12 t=13 t=14 t=15 t=16 t=17 t=18 I data segment data segment data segment data segment data segment data segment data segment data segment ACK ACK ACK ACK ACK ACK Ty A A V V htt TCP receiver t=6 t=7 t=8 t=9 t=10 t=11 t=12 t=13 What does the sender do at t=17? You can assume for this question that no timeouts have occurred.
Host A sends the information of size 3000 bytes to Host B using TCP protocol. As long as Host B receives each packet in size 1000 bytes, Host B must acknowledge Host A. We assume the header size in each packet is 40 bytes, the starting sequence number used by Host A is 1000, and the window size of the sender side is 3000 bytes. What is the value of RCV.NXT in Host B when the second packet in Host A is sent out and acknowledged? Question options: 1000 2000 3000 4000
TCP congestion control example. Consider the figure below, where a TCP sender sends 8 TCP segments at t = 1, 2, 3, 4, 5, 6, 7, 8. Suppose the initial value of the sequence number is 0 and every segment sent to the receiver each contains 100 bytes. The delay between the sender and receiver is 5 time units, and so the first segment arrives at the receiver at t = 6. The ACKS sent by the receiver at t = 6, 7, 8, 10, 11, 12 are shown. The TCP segments (if any) sent by the sender att = 11, 13, 15, 16, 17, 18 are not shown. The segment sent at t=4 is lost, as is the ACK segment sent at t=7. t=1 T data segment t=2+ data segment data segment-- t=3 TCP sender TCP receiver t=4+ t=5+ data segment - data segment t=6+ t36 data segment t=7 data segment t=8 data segment t=9 ACK + t=10 k -- ACK t=11 t=11 t=12 t=12 t=13 t=13 t=14 ACK -ACK ACK t=15 t=16 t=17 ACK t=18 What does the sender do at t=17? You can assume for this question that no timeouts have occurred.
Host A and B are communicating over a TCP connection, and Host B has already received all bytes up through byte 100 (including Byte 100) from A. Suppose Host A then sends two packets to Host B back-to-back. The first and second packets contain 40 and 80 bytes of data, respectively. Host B sends an acknowledgment whenever it receives a packet from Host A. a. What is the sequence number of the first packet sent from Host A to Host B? What is the sequence number of the second packet sent from Host A to Host B? b. If the second packet arrives before the first packet, in the acknowledgment of the first arriving packet, what is the acknowledgment number? .
Host A and B are communicating over a TCP connection, and Host B has already received from A all bytes up through byte 126. Suppose Host A then sends two segments to Host B backto-back. The first and second segments contain 80 and 40 bytes of data, respectively. In the first segment, the sequence number is 127, the source port number is 302, and the destination port number is 80. Host B sends an acknowledgment whenever it receives a segment from Host A. d. Suppose the two segments sent by A arrive in order at B. The first acknowledgment is lost and the second acknowledgment arrives after the first timeout interval. Draw a timing diagram, showing these segments and all other segments and acknowledgments sent. (Assume there is no additional packet loss.) For each segment in your figure, provide the sequence number and the number of bytes of data; for each acknowledgment that you add, provide the acknowledgment number.
Phases of TCP congestion control. Consider the figure below, which plots the evolution of TCP's congestion window at the beginning of each time unit (where the unit of time is equal to the RTT); see Figure 3.53 in the text. In the abstract model for this problem, TCP sends a "flight" of packets of size cwnd at the beginning of each time unit. The result of sending that flight of packets is that either (i) all packets are ACKed at the end of the time unit, (ii) there is a timeout for the first packet, or (iii) there is a triple duplicate ACK for the first packet. At the end of which units of time does TCP detect a triple-duplicate-ACK? Congestion window size (in segments) 40 35 25 20 10 5 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 Time unit (in RTT)
Host A and B are communicating over a TCP connection, and Host B has already received from A all bytes up through byte 126. Suppose Host A then sends two segments to Host B backto-back. The first and second segments contain 80 and 40 bytes of data, respectively. In the first segment, the sequence number is 127, the source port number is 302, and the destination port number is 80. Host B sends an acknowledgment whenever it receives a segment from Host A.a. In the second segment sent from Host A to B, what are the sequence number, source port number, and destination port number?b. If the first segment arrives before the second segment, in the acknowledgment of the first arriving segment, what is the acknowledgment number, the source port number, and the destination port number?c. If the second segment arrives before the first segment, in the acknowledgment of the first arriving segment, what is the acknowledgment number?d. Suppose the two segments sent by A arrive in order at B. The…