Figure 1-80 Sender Acknowledges ACK and Completes the Three-Way Handshake
With the three-way handshake completed, TCP can inform the application that the session
has been established. This is shown in Figure 1-81.
TCP: Got the ACK.
SRC IP
192.168.3.2
SRC MAC
0800:0222:1111
DST MAC
0800:0222:2222
DST IP
192.168.3.1
SYN
ACK
SRC IP
192.168.3.2
DST IP
192.168.3.1
SYN
ACK
SYN
ACK
Layer 3 = 192.168.3.1
Layer 2 = 0800:0222:2222
Layer 3 = 192.168.3.2
Layer 2 = 0800:0222:1111
TCP: I need to let the other end know I got the
SYN ACK to complete the session establishment.
SRC IP
192.168.3.1
SRC MAC
0800:0222:2222
DST MAC
0800:0222:1111
DST IP
192.168.3.2
TCP
ACK
SRC IP
192.168.3.2
SRC MAC
0800:0222:2222
DST MAC
0800:0222:1111
DST IP
192.168.3.2
TCP
ACK
SRC IP
192.168.3.1
DST IP
192.168.3.2
TCP
ACK
TCP
ACK
Layer 3 = 192.168.3.1
Layer 2 = 0800:0222:2222
Layer 3 = 192.168.3.2
Layer 2 = 0800:0222:1111
Exploring the Packet Delivery Process 97
Figure 1-81 Session Is Open
Now the application can send the data over the session, relying on TCP for error detection.
Figures 1-82 through 1-84 show this operation.
Figure 1-82 Data Flow Begins
Application: OK, I??™ll send you some data.
Pages:
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158