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	English
	Which are the mechanisms that should be included in a transport protocol providing an unreliable connectionless transport service that can detect transmission errors, but not correct them ?
	What is piggybacking and what are the benefits of this technique ?
	What are the acknowledgments sent by `Host B`. How does `Host A` react and how does it terminate the connection ?
	This is an unpolished draft of the third edition of this e-book. If you find any error or have suggestions to improve the text, please create an issue via https://github.com/CNP3/ebook/issues?milestone=3 or help us by providing pull requests to close the existing issues.
	Some transport protocols use 32 bits sequence numbers while others use 64 bits sequence number. What are the advantages and drawbacks of each approach ?
	Serving applications
	Same question as above, but consider now that the transport protocol tries to send large DATA segments whenever possible. For this exercise, we consider that a DATA segment can contain up to 8 bytes of data in the payload. Do not forget to show the acknowledgments in your answer.
	Practice
	Open questions
	Multiple choices questions
	In the transport layer, the receive window advertised by a receiver can vary during the lifetime of the connection. What are the causes for these variations ?
	In the above example, the two `DATA` segments were lost before arriving at the destination. Discuss the following scenario and explain how the receiver should react to the reception of the last `DATA` segment.
	Footnotes
	Discussion questions
	DATA segments contain a sequence number that is incremented for each DATA segment transmitted
	DATA segments contain a sequence number that is incremented for each byte transmitted
	Continue the connection so that `Host B` sends `Hello` as data and `Host A` replies by sending `Pleased to meet you`. After having received the response, `Host B` closes the connection gracefully and `Host A` does the same. Discuss on the state that needs to be maintained inside each host.
	Consider a transport protocol that provides the bytestream service and uses 32 bits sequence number to represent the position of the first byte of the payload of DATA segments in the bytestream. How would you modify this protocol so that it can provide a message-mode service ? Consider first short messages that always fit inside a single segment. In a second step, discuss how you could support messages of unlimited size.
	Consider a transport protocol that provides a reliable connection-oriented bytestream service. You observe the segments sent by a host that uses this protocol. Does the time-sequence diagram below reflects a valid implementation of this protocol ? Justify your answer.
	Consider a reliable connection-oriented transport protocol that provides the bytestream service. In this transport protocol, the sequence number that is placed inside each DATA segment reflects the position of the bytes in the bytestream. Considering the connection shown below, provide the DATA segments that are sent by `Host A` in response to the `DATA.request`, assuming that one segment is sent for each `DATA.request`.