Brocade_IP_Primer_eBook

Chapter 2: TCP/IP
In summary, the 3-way handshake looks like this:
1. Client sends TCP SYN to server
2. Server sends TCP SYN/ACK to client
3. Client sends TCP ACK to server
Windows and Acknowledgments
Now you've initiated the session. It's time to start communicating. Here, the client
requests some data. The server sends an acknowledgment (ACK) to tell
the client that it has received the request. Now the server will start sending
segments.
In our example, let's say that the server is going to send 20 kilobytes (20,480
bytes) of data. The Transport Layer, on the server side, is going to divide that
20 KB into several segments. It's going to number the segments so that the client
will know how to reassemble them, and to make sure that it received them
all. When the server starts sending segments, it will send a few at a time and
wait for an acknowledgment from the client. This is the window.
The window is measured in bytes, not segments. The server will send segments
until it has reached the window size. In our example, let's say that the
window size of the server is 5,120 bytes (5 KB). That means that the server
will send segments until it has sent 5 KB worth of segments. Then it will wait to
receive an acknowledgment (ACK) from the client. When it does, it will send
another 5 KB worth of segments, and so on.
Request Data
TCP ACK
TCP ACK
1 KB Segment
1 KB Segment
1 KB Segment
1 KB Segment
1 KB Segment
1 KB Segment
1 KB Segment
1 KB Segment
1 KB Segment
1 KB Segment
58 Brocade IP Primer