TCP cumulative acknowledgement and window value update

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Pictured , We can see TCP Adopt cumulative confirmation mechanism , Four packets , Only one confirmation message was replied , And it is the confirmation of the last received datagram .

In my Mac Send to previous TCP After the confirmation of the data package , The window value is determined by the previous 262144-1440*4=256384, But after confirmation, the data will be output to the buffer soon , So the next packet is TCP Window update packet . The window value becomes 262144

From here we can know ,TCP Adopt cumulative confirmation