TCP: sliding window of flow control

TCP: sliding window of flow control

1Content table

• Sliding window example

• Sliding window, TX sequence number, RX acknowledge number, RX window size

2Sliding window example

There are numerous points that we can summarize using this figure as an example.

1. The sender does not have to transmit a full window's worth of data.

2. One segment from the receiver acknowledges data and slides the window to the right. This is because the window size is relative to the acknowledged sequence number.

3. The size of the window can decrease, as shown by the change from segment 7 to segment 8, but the right edge of the window must not move leftward.

4. The receiver does not have to wait for the window to fill before sending an ACK. We saw earlier that many implementations send an ACK for every two segments that are received.

 

3Sliding window, TX sequence number, RX acknowledge number, RX window size

4Reference

1. chapter 20, Vol 1, TCP/IP Illustrated ed1