Go-back-n

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Vennligst svar på alle spørsmål. Intern feil {} har ikke gyldig filetternavn. {} veier for mye.

Spørsmål 1: Frames sent by a go-back-n sender

You implement a Go-back-n sender and observe the following frames that you send/receive. Assume that you use a window of three frames.

The receiver has correctly received the three frames that you have sent, but one acknowledgement has been lost.

The receiver has correctly received the first two frames. The third frame and the first acknowledgement have been lost.

The receiver has only received the first frame that you have sent. It has neither received the second nor the third frame.

Spørsmål 2: A go-back-n sender

You implement a Go-back-n sender and observe the following frames that you send/receive. Assume that you use a window of three frames.

Which affirmation is correct among the ones below:

The receiver has correctly received the first and the third frame that your have sent. The second frame has been lost and should be retransmitted.

The receiver has correctly received the first two frames. The third frame and the second acknowledgements have been lost.

The receiver has only received the first frame that you have sent. It has neither received the second nor the third frame.

Spørsmål 3: A go-back-n sender

You implement a Go-back-n sender and observe the following sequence of frames. Assuming that you have a window of three segments.

Among the following affirmations, only one is correct. Which one ?

Since you never received C(OK,0), there was something wrong in the transmission of the first frame. You retransmit all frames upon expiration of your retransmission timer.

After having received C(OK,1), you know that the first two frames have been received correctly. You retransmit immediately the frame D(2,c) that has not been received correctly.

After having received C(OK,1), you know that the first two frames have been received correctly. Since you never received an acknowledgement for the third frame, you will retransmit it after the expiration of the associated retransmission timer.

Spørsmål 4: A go-back-n receiver

You implement a go-back-n receiver and receive the following frames.

How do you respond to the reception of the frame D(2,b) ?

You issue a Data.ind(b) to deliver the information to your user and respond with C(OK,2).

You ignore the out-of-sequence frame and respond with C(OK,0).

You place the frame in your buffer and respond with C(OK,2).

Forfatter(e)	Olivier Bonaventure
Frist	Ingen frist
Innleveringsgrense	Ingen begrensning
Kategorimerkelapper	reliable

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