Networking 1 - Module 6 - Videos 1-9

The following frame was "sniffed" off an Ethernet network. Below, we removed the preamble and the frame header. We use only hexadecimal numbers without using "0x" or "h" symbols. Below are the IP and TCP headers. Here is the IP packet in network byte order: 45 6F 06 00 01 24 00 00 40 06 56 7A 83 CC 0E 65 83 CC 34 43 23 00 4E 21 5E 32 78 1C 12 67 89 E2 50 10 00 34 67 F1 B3

A TCP segment 2300 4E21

Check all true statements about the Weekly Pocket Money Problem.

A child may request and receive all the available weekly allocation B. Some children may not ask for any pocket money on some weeks

TCP offers these services

Addressing Congestion control Reliable in-order delivery Error correction Error detection Flow control

Opening a TCP connection performs these functions:

Agree on the initial sequence numbers used by server and client Agree on a maximum segment size

In the TCP/IP reference model, the transport layer provides service directly to the _______ layer.

Application

In the OSI reference model, these services are offered by both the transport and data link layers.

Error control Flow control Addressing

In order to detect corrupted messages sent by the sender, these mechanisms may help at the receiver.

Error detection Checksum

For reliability, a timer is necessary at the receiver if the channel only corrupt packets payloads.

False

For reliability, a timer is necessary at the sender if the channel only corrupts packets's payloads.

False

In the TCP/IP model, an application message can be a packet's payload.

False

In the TCP/IP reference model, a UDP datagram can be a frame's payload

False

The transport layer may offer these services

Flow control Congestion Control Reliability

During its "lifetime", a TCP connection will go through these phases

Full duplex data exchange Three way hand-shake Closing

These application layer protocols use usually TCP at the transport layer.

HTTP SSH FTP

A client sends five equal sized segments with sequence numbers 15, 35, 55, 75, 95 Segments with sequence numbers 55 and 75 get lost. The server will likely send a segment with sequence number ______ after receiving segment with sequence number 95.

None of these answers

In order to detect corrupted messages sent by the sender, these mechanisms may help at the sender.

None of these answers

In order to detect lost messages sent by the sender, these mechanisms may help at the receiver.

None of these answers

The UDP header can have up to _______ bytes for optional fields.

None of these answers

___________ is necessary when _________ at the sender is lower (than at the receiver).

None of these answers

A server sends a 10 bytes segment with sequence number 0. The client receives it correctly. The client will respond with Sequence number

None of these choices

A server sends a 1000 bytes segment with sequence number 3500. The client receives it correctly. The client will respond most likely with Sequence number

None of these choices

A server sends a 1000 bytes segment with sequence number 3500. The client receives it correctly. The client will respond most likely with Sequence number_________.

None of these choices

On an Ethernet frame, the ________ field will consist of an IP packet, an ARP request/response, or some other network protocols data units.

Payload

In the TCP/IP reference model, transport layers use ___________ for addressing.

Port numbers

In the OSI reference model, the transport layer provides service directly to the _______ layer.

Session

These protocols are transport layer protocols used over the Internet.

TCP UDP

In order to detect lost messages sent by the sender, these mechanisms may help at the sender.

Timer

For reliability, a timer is necessary at the sender if the channel can loose packets

True

In the OSI reference model, A transport protocol data unit (TPDU) is encapsulated inside a network protocol data unit

True

In the TCP/IP reference model, a packet can be a frame's payload.

True

In the TCP/IP reference model, a segment can be a packet's payload

True

In the TCP/IP reference model, an application message can be a datagram's payload

True

In the TCP/IP reference model, an application message can be a segment's payload.

True

Pair/Matching related expressions/variables. Flow control Congestion control Offered windows

Wa: advertised value by the receiver cwnd :a variable maintained by the sender to adapt to the network conditions Min(Wa, cwnd)

Select the best answer from each dropdown menu. The following frame was "sniffed" off an Ethernet network. Below, we removed the preamble and the frame header. We use only hexadecimal numbers without using "0x" or "h" symbols. Below are the IP and TCP headers. Here is the IP packet in network byte order: 46 6F 06 00 01 24 00 00 40 06 56 7A 83 CC 0E 65 83 CC 34 43 23 00 4E 21 5E 32 78 1C 12 67 89 E2 50 10 00 34 67 F1 B3 This IP packet carries __________ The source port number is ___________ The destination port number is .

a TCP segment 5E32 781C

The following frame was "sniffed" off an Ethernet network. Below, we removed the preamble and the frame header. We use only hexadecimal numbers without using "0x" or "h" symbols. Below are the IP and TCP headers. Here is the IP packet in network byte order: 46 6F 06 00 01 24 00 00 40 06 56 7A 83 CC 0E 65 83 CC 34 43 23 00 4E 21 5E 32 78 1C 12 67 89 E2 50 10 00 34 67 F1 B3

a TCP segment 5E32 781C

The following frame was "sniffed" off an Ethernet network. Below, we removed the preamble and the frame header. We use only hexadecimal numbers without using "0x" or "h" symbols. Below are the IP and TCP headers. Here is the IP packet in network byte order: 45 6F 06 00 01 24 00 00 40 06 56 7A 83 CC 0E 65 83 CC 34 43 4E 4E 21 23 00 78 1C 5E 32 12 67 89 E2 50 10 00 34 F1 B3

a TCP segment None of these answers None of these answers

The following frame was "sniffed" off an Ethernet network. Below, we removed the preamble and the frame header. We use only hexadecimal numbers without using "0x" or "h" symbols. Below are the IP and TCP headers. Here is the IP packet in network byte order: 45 6F 06 00 01 24 00 00 40 06 56 7A 83 CC 0E 65 83 CC 34 43 4E 4E 21 23 00 78 1C 5E 32 12 67 89 E2 50 10 00 34 F1 B3 This IP packet carries a TCP segment . The source port number is None of these answers . The destination port number is None of these answers . This IP packet carries The source port number is The destination port number is

a TCP segment None of these answers None of these answers

Select the best answer from each dropdown menu. The following frame was "sniffed" off an Ethernet network. Below, we removed the preamble and the frame header. We use only hexadecimal numbers without using "0x" or "h" symbols. Below are the IP and TCP headers. Here is the IP packet in network byte order: 45 6F 06 00 01 24 00 00 40 11 56 7A 83 CC 0E 65 83 CC 34 43 4E 4E 21 23 00 78 1C 5E 32 12 67 89 E2 50 10 00 34 F1 B3 This IP packet carries The source port number is The destination port number is

a UDP datagram None of these answers None of these answers

The objective(s) of congestion control is (are) to :

allocate a fair share of the available bandwidth maximize throughput

In the TCP/IP model, a _________ is for a ________ what a packet is for a segment.

frame:packet

Assuming that flow control is used, congestion control is necessary to protect the input buffers of these devices from overflowing

intermediary nodes

Assuming that congestion control is not used, flow control protects the input buffers of these devices from overflowing.

receiver

Assuming that congestion control is used, flow control protects the input buffers of these devices from overflowing.

receiver

The acknowledgement (ack) number in the TCP header is

the number of the next expected byte (to be received)

Answer this question in the context of the strategy described in class and adopted by each child to manage Weekly Pocket Money Problem. After six months using this strategy, $40 dollars is the highest sum that a child ever requested and received without being smacked. In the future, the highest amount that a child can ask without being smacked for sure is __________.

$0

Answer this question in the context of the strategy described in class and adopted by each child to manage Weekly Pocket Money Problem. This week, the child asked and received $40. Next week, the child can certainly ask for and receive ______ without being smacked for sure.

$0

A client has in its sending buffer these equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. Based on congestion control and flow control, its offered window is 20 bytes. So far, the client sent segments with Sequence numbers 15, 25, and 35. The highest acknowledgement it received is 25. The next segment that the client could send is segment with Sequence number to __________ . (Answer -1 if the client cannot send anymore new segments).

-1

Answer this question based congestion control and flow control as performed by TCP. Suppose that a TCP sender 1) has cwnd set to 8,000 bytes 2) has 4,000 bytes available in its own input buffers 3) receives a segment with an advertised window of 0 bytes. The TCP sender will set its offered window Wnd to ________ bytes.

0

Assume a recent TCP implementation (TCP Reno and beyond). Let the congestion window be 12 segments and all 12 outstanding segments get lost. The congestion window will then be set by the sender to ________ segment(s).

1

Assume a recent TCP implementation (TCP Reno and beyond). Let the congestion window be 16 segments and all 16 outstanding segments get lost. The congestion window will then be set by the sender to ________ segment(s).

1

A client sends multiple equal sized segments with sequence numbers 15, 25, 35,45, and 55. The size of these segments is ________ bytes.

10

A client sends seven equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. The size of each segment was ________ bytes.

10

Answer this question in the context of the strategy described in class and adopted by each child to manage Weekly Pocket Money Problem. A child starts numbering weeks from 0 (zero) when he get smacked. On Week 0 he got smacked when he asked 16 dollars. Assuming that the child asks for money each week, the child will ask _____ dollars on Week 5.

10

Answer this question in the context of the strategy described in class and adopted by each child to manage Weekly Pocket Money Problem. A child starts numbering weeks from 0 (zero) when he get smacked. On Week 0 he got smacked when he asked 16 dollars. Assuming that the child asks for money each week, the child will ask _____ dollars on Week 6.

11

Answer this question in the context of the strategy described in class and adopted by each child to manage Weekly Pocket Money Problem. A child starts numbering weeks from 0 (zero) when he get smacked. On Week 0 he got smacked when he asked 20 dollars. Assuming that the child asks for money each week, the child will ask _____ dollars on Week 5.

11.625

A TCP client receives a segment that contains a segment with 100 bytes of data with Sequence number 1000. This TCP client will acknowledge this segment with an ack number equal to ______

1100

Answer this question based congestion control and flow control as performed by TCP. Suppose that a TCP sender 1) has cwnd set to 18,000 bytes 2) has 10,000 bytes available in its own input buffers 3) receives a segment with an advertised window of 12,000 bytes. The TCP sender will set its offered window Wnd to ________ bytes.

12000

A TCP client receives a segment that contains a segment with 5 bytes of data with Sequence number 10. This TCP client will acknowledge this segment with an ack number equal to

15

A TCP client receives a segment that contains a segment with 5 bytes of data with Sequence number 10. This TCP client will acknowledge this segment with an ack number equal to ______

15

A TCP client receives a segment that contains a segment with 10 bytes of data with Sequence number 6. This TCP client will acknowledge this segment with an ack number equal to ______

16

A client has in its sending buffer these equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. Based on congestion control and flow control, its offered window is 40 bytes. So far, the client sent segments with Sequence numbers 15, 25, and 35. The highest acknowledgement it received is 25. This client could send up to __________ new segment(s). (Answer -1 if the client cannot send anymore new segments).

2

A client sends seven equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. Segments with sequence numbers 45 and 65 get lost. The client will receive _______ duplicate acknowledgements after the server received segment #75.

2

Let the advertised window Wa (by the received) be 4 segments and the current congestion window cwnd be 32 segments. Supposed that there are 2 outstanding segments (segments sent and not yet acknowledged). The sender can send at most _________ segment(s).

2

Suppose that cwnd = 1,000 bytes. The latest segment received by a client had the advertised window set to 40 bytes. The client has in its sending buffer these equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. So far, the client sent segments with Sequence numbers 15, 25, and 35. The highest acknowledgement it received is 25. This client could send up to __________ new segments. (Answer -1 if the client cannot send anymore new segments).

2

Suppose that cwnd = 30 bytes. The latest segment received by a client had the advertised window set to 40 bytes. The client has in its sending buffer these equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. So far, the client sent segments with Sequence numbers 15, 25, and 35. The highest acknowledgement it received is 35. This client could send up to __________ new segments. (Answer -1 if the client cannot send anymore new segments).

2

A client has in its sending buffer these equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. Based on congestion control and flow control, its offered window is 40 bytes. So far, the client sent segments with Sequence numbers 15, 25, and 35. The highest acknowledgement it received is 25. This client could send up to __________ new segment(s). (Answer -1 if the client cannot send anymore new segments).

20

Suppose that cwnd = 1,000 bytes. The latest segment received by a client had the advertised window set to 40 bytes. The client has in its sending buffer these equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. So far, the client sent segments with Sequence numbers 15, 25, and 35. The highest acknowledgement it received is 25. This client could send up to __________ new bytes. (Answer -1 if the client cannot send anymore new segments).

20

A client sends seven equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. Segments with sequence numbers 25 and 65 get lost. The server will send acknowledgement number ______ after receiving segment with sequence number 75

25

A client has in its sending buffer these equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. Based on congestion control and flow control, its offered window is 30 bytes. So far, the client sent segments with Sequence numbers 15, 25, and 35. The highest acknowledgement it received is 45. This client could send up to __________ new segment(s). (Answer -1 if the client cannot send anymore new segments).

3

A client has in its sending buffer these equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. Based on congestion control and flow control, its offered window is 40 bytes. So far, the client sent segments with Sequence numbers 15, 25, and 35. The highest acknowledgement it received is 35. This client could send up to __________ new byte(s). (Answer -1 if the client cannot send anymore new segments).

30

Let the advertised window Wa (by the received) be 40 segments and the current congestion window cwnd be 32 segments. Supposed that there are 2 outstanding segments (segments sent and not yet acknowledged). The sender can send at most _________ segments.

30

Suppose that cwnd = 30 bytes. The latest segment received by a client had the advertised window set to 40 bytes. The client has in its sending buffer these equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. So far, the client sent segments with Sequence numbers 15, 25, and 35. The highest acknowledgement it received is 45. This client could send up to __________ new bytes. (Answer -1 if the client cannot send anymore new segments).

30

A client sends five equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. Segments with sequence numbers 35 and 65 get lost. The server will send acknowledgement number ______ after receiving segment with sequence number 55.

35

A client sends five equal sized segments with sequence numbers 15, 35, 55, 75, 95 Segments with sequence numbers 55 and 75 get lost. The server will send acknowledgement number ______ after receiving segment with sequence number 15

35

Answer this question in the context of the strategy described in class and adopted by each child to manage Weekly Pocket Money Problem. A child starts numbering weeks from 0 (zero) when he get smacked. On Week 0 he got smacked when he asked 24 dollars. Assuming that the child asks for money each week, the child will ask _____ dollars on Week 3.

4

Answer this question in the context of the strategy described in class and adopted by each child to manage Weekly Pocket Money Problem. A child starts numbering weeks from 0 (zero) when he get smacked. On Week 0 he got smacked when he asked 32 dollars. Assuming that the child asks for money each week, the child will ask _____ dollars on Week 3.

4

Assume a recent TCP implementation (TCP Reno and beyond). Let the advertised window Wa (by the received) be 4 segments and the current congestion window cwnd be 32 segments. A timeout occurs. The sender can send up to _______ segments after 5 successful bursts (since the timeout).

4

The UDP header consists of ______ fields (members) of information.

4

A client has in its sending buffer these equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. Based on congestion control and flow control, its offered window is 40 bytes. So far, the client sent segments with Sequence numbers 15, 25, and 35. The highest acknowledgement it received is 45. This client could send up to __________ new byte(s). (Answer -1 if the client cannot send anymore new segments).

40

Suppose that cwnd = 1,000 bytes. The latest segment received by a client had the advertised window set to 40 bytes. The client has in its sending buffer these equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. So far, the client sent segments with Sequence numbers 15, 25, and 35. The highest acknowledgement it received is 45. This client could send up to __________ new bytes. (Answer -1 if the client cannot send anymore new segments).

40

A client sends seven equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. Segments with sequence numbers 45 and 65 get lost. The client will receive the acknowledgement number ______________ after the server receives segment #75.

45

A server sends a 1000 bytes segment with sequence number 3500. If everything goes well, it will send the next segment with sequence number _________.

4500

Let the congestion window be 10 segments and one segment gets lost triggering three dupacks (duplicate acks). The slow start threshold (ssthreshold) is then set to ________ segment(s).

5

A client sends five equal sized segments with sequence numbers 15, 35, 55, 75, 95 Segments with sequence numbers 55 and 75 get lost. The server will likely send a segment with acknowledgement number ______ after receiving segment with sequence number 35.

55

A client sends five equal sized segments with sequence numbers 15, 35, 55, 75, 95 Segments with sequence numbers 55 and 75 get lost. The server will likely send a segment with acknowledgement number ______ after receiving segment with sequence number 95.

55

A client sends seven equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. Segments with sequence numbers 55 and 65 get lost. The client will receive the acknowledgement number ______________ after the server receives segment #75.

55

Suppose that cwnd = 1,000 bytes. The latest segment received by a client had the advertised window set to 40 bytes. The client has in its sending buffer these equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. So far, the client sent segments with Sequence numbers 15, 25, and 35. The highest acknowledgement it received is 25. This client could send new segments with Sequence number up to __________ . (Answer -1 if the client cannot send anymore new segments).

55

Let the congestion window be 12 segments and all 12 outstanding segments get lost. The slow start threshold will then be set by the sender to ________ segment(s).

6

A client has in its sending buffer these equal sized segments with sequence numbers 15, 25, 35,45, 55, 65, and 75. Based on congestion control and flow control, its offered window is 40 bytes. So far, the client sent segments with Sequence numbers 15, 25, and 35. The highest acknowledgement it received is 35. This client could send new segments with Sequence number up to __________ . (Answer -1 if the client cannot send anymore new segments).

65

Answer this question in the context of the strategy described in class and adopted by each child to manage Weekly Pocket Money Problem. A child starts numbering weeks from 0 (zero) when he get smacked. On Week 0 he got smacked when he asked 16 dollars. Assuming that the child asks for money each week, the child will ask _____ dollars on Week 4.

8

Answer this question in the context of the strategy described in class and adopted by each child to manage Weekly Pocket Money Problem. A child starts numbering weeks from 0 (zero) when he get smacked. On Week 0 he got smacked when he asked 20 dollars. Assuming that the child asks for money each week, the child will ask _____ dollars on Week 4.

8

Assume a recent TCP implementation (TCP Reno and beyond). Let the congestion window be 16 segments and one segment is lost. The congestion window will then be set by the sender to ________ segment(s).

8

The size of a UDP header has ________ bytes.

8

Answer this question based congestion control and flow control as performed by TCP. Suppose that a TCP sender 1) has cwnd set to 8,000 bytes 2) has 4,000 bytes available in its own input buffers 3) receives a segment with an advertised window of 12,000 bytes. The TCP sender will set its offered window Wnd to ________ bytes.

8000

A client sends multiple equal sized segments with sequence numbers 150, 240, 330,420, and 510. The size of these segments is ________ bytes.

90