Topic

Flow Control

3 questions in this topic.

2013 Q2(d)Transport LayerFlow Control· 4 marks

What, other than congestion control, limits the sending rate to TCP? Explain how this other limit works.

TCP windowreceive window

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2014 Q2(e)Transport LayerFlow Control· 2 marks

TCP flow control relies on the receiver to indicate how much buffer space is available for data at the receiver. How does the receiver provide this information to the sender?

receive windowTCP window

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2015 Q2(e)Transport LayerFlow Control· 3 marks

A TCP sender finds out the available receive buffer space through the ‘receive window’ header field of packets/acknowledgments sent by the receiver to the sender. The flaw in this approach is that if the receiver has no space, it will send a receive window of 0. This indicates that the sender should not send any more data as there is no space in the receiver’s buffer. However, if the sender does not send data, the receiver may never send a packet to tell the sender when there is space. Assuming we do not want the receiver to gratuitously send packets to the sender just to tell it about window space (ie the receiver should only send packets to the sender if it either has data to send or if it is sending an acknowledgement), what can the sender do resolve this problem?

TCPreceive windowpersist timer

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