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 -

A router interconnects a subnet, where all the interfaces of the subnets must have the prefix 164.132.62/24. suppose that the Subnet is required to support up to 60 interfaces, provide a network address that satisfies the above.

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In modern packet-switched networks, including the Internet, the source host segments long, application-layer messages (for example, an image or a music file) into smaller packets and sends the packets into the network. The receiver then reassembles the packets back into the original message. We refer to this process as message segmentation. Figure 1.27 illustrates the end-to-end transport of a message with and without message segmentation. Consider a message that is 8. 106 bits long that is to be sent from source to destination in Figure 1.27. Suppose each link in the figure is 2 Mbps. Ignore propagation, queuing, and processing delays. a. Consider sending the message from source to destination without message segmentation. How long does it take to move the message from the source host to the first packet switch? Keeping in mind that each switch uses store-and-forward packet switching, what is the total time to move the message from source host to destination host? b. Now suppose that…

Consider one TCP connection on a path with a bottleneck link with capacity L. We have a file of size F(assume F is a very large file size). If TCP segment size is B bytes, the two-way propagation delay is tp and connection is always in congestion avoidance phase, find the following: A. Maximum window size that TCP can achieve B. Average window size and average throughput in this TCP connection C. Time it will take from connection establishment to reaching the maximum window size.

1. Consider the following protocol for adding money to a debit card. (i) User inserts debit card into debit card machine. (ii) Debit card machine determines current value of card (in dollars), which is stored in variable x. (iii) User inserts dollars into debit card machine and the value of the inserted dollars is stored in variable y. (iv) User presses enter button on debit card machine. (v) Debit card machine writes value of x + y dollars to debit card and ejects card. Recall the discussion of race conditions. This particular protocol has a race condition. a. What is the race condition in this protocol? b. Describe a possible attack that exploits the race condition. c. How could you change the protocol to eliminate the race condition, or at least make it more difficult to exploit?

A connection that connects two hosts may transport many packets at the same time. Please provide a schedule that outlines all of the actions that need to be completed in order to successfully execute one shipment. Is it to be anticipated that one of the delays will take a certain amount of time, while the duration of the other delay may be adjusted in accordance with the circumstances?

Consider a simple protocol for transferring files over a link. After some initial negotiation, A sends data packets of size 1 KB to B; B then replies with an acknowledgment. A always waits for each ACK before sending the next data packet; this is known as stop-and-wait. Packets that are overdue are presumed lost and are retransmitted. (a) In the absence of any packet losses or duplications, explain why it is not necessary to include any "sequence number" data in the packet headers. (b) Suppose that the link can lose occasional packets, but that packets that do arrive always arrive in the order sent. Is a 2-bit sequence number (that is, N mod 4) enough for A and B to detect and resend any lost packets? Is a 1-bit sequence number enough? (c) Now suppose that the link can deliver out of order and that sometimes a packet can be delivered as much as 1 minute after subsequent packets. How does this change the sequence number requirements?

A connection that connects two hosts may transport many packets at the same time. Please provide a schedule that outlines all of the actions that need to be completed in order to successfully execute one shipment. Is it to be anticipated that one of the delays will take a certain amount of time, while the duration of the other delay may be adjusted in accordance with the circumstances?

Suppose two TCP connections share a path through a router R. The router's queue size is six segments; each connection has a stable congestion window of three segments. No congestion control is used by these connections. A third TCP connection now is attempted, also through R. The third connection does not use congestion control either. Describe a scenario in which, for at least a while, the third connection gets none of the available bandwidth, and the first two connections proceed with 50% each. Does it matter if the third connection uses slow start? How does full congestion avoidance on the part of the first two connections help solve this?