Shulou(Shulou.com)06/03 Report--

Preface

TCP belongs to the fourth layer (transport layer) in the OSI seven-layer model, which helps us deal with the details of the transport layer. It includes current limitation, packet loss, network transmission disorder and so on. So how on earth does TCP achieve current restriction?

If you need to review the basics, please poke here "introduction to the basics of TCP/IP". The blogger is lazy and will make up next week.

The receiver buffer is full.

If the sender transmission speed is fast, the reciever processing speed is slow. What will happen?

After a while, reciever's buffer is full.

When the reciever buffer is full, tell sender through ack (win=0) not to send me any more data, and I can't handle it. Sender will stop sending data. After a while, after reciever processes the data, the buffer has free space. Declare your window size through ack. Sender continues to send data and slide the window out.

Through the animation, we can directly see the window sliding to the right, so it is called the sliding window.

Before decomposing the action before sliding

What information does the diagram contain? Let's break it down.

The window size of the receiver is outside the 6 window, and the ack has been sent and received on the left. This part of the data can be discarded. 12-14 indicates that an ack has been sent but not received. (cannot be discarded, it may need to be resent) 15-17 is unsent data. Because the unconfirmed data is less than 6, it can be sent quickly outside the window, with unsent data on the right, but because the window is full, it cannot be sent after sliding.

Sender receives the confirmation packet window from ack=12. The data in the right slide window is changed to 13-18 summary.

The above is the sliding window in TCP/IP.

Sliding window is also an algorithm for service flow restriction.

Other

Some students may ask, what will the sliding window look like if you first receive a confirmation packet from ack=13? Let's go straight to the picture!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.