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Please explain ques 43 .
asked in Computer Networks by Loyal (8k points) | 120 views
If it is asking about congestion window, then equation used

unacknowledgeByte=Last Byte Sent - Last Byte Acknowledged $\leq$ min(cwnd,rwnd)

1 Answer

+1 vote

Answer will be D)

Sender window Size will be =Sequence Number of Last Frame Send- Sequence number of last acknowledgement received 

Receiver Window Size=Sequence Number of largest accepted Frame- Sequence number last frame received

Sequentially acceptance of frame required here. Because otherwise, we cannot locate, where there is any lost frame or corrupted frame

Below picture is for SR protocol which clears how SWS and RWS is changing with respect to sending of packets and receiving acknowledgement

In the diagram Sender window size will not change until 1st ACK is received

Similarly, receiver will not change it's window size, if there is lost frame in middle. When lost frame received , then only receiver will  slide it's frame buffer to it's next frame

answered by Veteran (107k points)
edited by
Please explain how

 Sender window Size will be =Sequence Number of Last Frame Send-Last Sequentially packet received

For instance sequence no of last frame sent is 3 and last sequentially packet received is 0 , so 3-0=0 but sender window size is 4 .

Also how this is true ?

Receiver Window Size=Sequence Number of last accepted Frame- Receiver window Size

Both on LHS and RHS we have receiver window size ?
Sequence number means "How many packets the sender can send out on the net before it  wait for an ACK" Here maximum 4 packet we can send before get an ACK

Say first packet 0 is send with sequence number 0

Now, until 0 is received as an ACK , keep track of packet 0.

Now, sender has a maximum buffer size 4, So, upto packet 3 it waits for an ACK

After, that sender buffer is full.

So, it will wait no more and and resend packet 0

i.e., maximum sender window size will be 3rd packet-0th packet=4


also size of receiver buffer cannot change, but receiver window size can change


@srestha mam, can you please explain which is receiver or sender window and buffer here?

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