Fast retransmit: Difference between revisions
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A TCP sender uses timers to recognize lost segments. If an acknowledgement is not received for a particular segment with a specified time (a function of the estimated [[Round-trip delay time]]), the sender will assume the segment was lost in the [[Computer network | network]], and will retransmit the segment. |
A TCP sender uses timers to recognize lost segments. If an acknowledgement is not received for a particular segment with a specified time (a function of the estimated [[Round-trip delay time]]), the sender will assume the segment was lost in the [[Computer network | network]], and will retransmit the segment. |
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The fast retransmit enhancement works as follows: if a TCP sender receives three duplicate acknowledgements with the same acknowledge number (that is, a total of four acknowledgements with the same acknowledgement number), the sender can be reasonably confident that the segment with that sequence number was dropped, and will not arrive out of order. The sender will then retransmit the packet that |
The fast retransmit enhancement works as follows: if a TCP sender receives three duplicate acknowledgements with the same acknowledge number (that is, a total of four acknowledgements with the same acknowledgement number), the sender can be reasonably confident that the segment with that sequence number was dropped, and will not arrive out of order. The sender will then retransmit the packet that wa presumed dropped before waiting for its timeout. |
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== External links == |
== External links == |
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Revision as of 23:17, 8 April 2007
Fast Retransmit is an enhancement to TCP which reduces the time a sender waits before retransmitting a lost segment.
A TCP sender uses timers to recognize lost segments. If an acknowledgement is not received for a particular segment with a specified time (a function of the estimated Round-trip delay time), the sender will assume the segment was lost in the network, and will retransmit the segment.
The fast retransmit enhancement works as follows: if a TCP sender receives three duplicate acknowledgements with the same acknowledge number (that is, a total of four acknowledgements with the same acknowledgement number), the sender can be reasonably confident that the segment with that sequence number was dropped, and will not arrive out of order. The sender will then retransmit the packet that wa presumed dropped before waiting for its timeout.
External links
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