RFC 793 State machine study
3-way handshake Page 31, Figure 7
3-way handshake TCP A TCP B SEQ=NA Page:31 Figure CLOSED LISTEN SEQ=NA SEQ=300 Should_ACK=NA
3-way handshake TCP A TCP B SEQ=NA SEQ=300 Page:31 Figure CLOSED LISTEN 2. SYN-SENT --> --> SYN-RECEIVED SEQ=100 SEQ=100 CTL=SYN ACK= DATA= Should_ACK=NA Should_ACK=101
3-way handshake TCP A TCP B SEQ=300 Page:31 Figure SYN-SENT --> --> SYN-RECEIVED 3. ESTABLISHED <-- SYN-RECEIVED SEQ=100 CTL=SYN ACK= DATA= SEQ=300 CTL=SYN ACK=101 DATA= SEQ=100 Should_ACK=NA Should_ACK=101 Should_ACK=301 SEQ=101
3-way handshake TCP A TCP B SEQ=300 Page:31 Figure ESTABLISHED <-- SYN-RECEIVED 4. ESTABLISHED --> --> ESTABLISHED SEQ=300 CTL=SYN ACK=101 DATA= SEQ=101 Should_ACK=101 Should_ACK=301 SEQ=100 CTL= ACK=301 DATA= Should_ACK=101 SEQ=301
3-way handshake TCP A TCP B SEQ=301 Page:31 Figure ESTABLISHED --> --> ESTABLISHED 5. ESTABLISHED --> --> ESTABLISHED SEQ=101 Should_ACK=101 Should_ACK=301 SEQ=100 CTL= ACK=301 DATA= SEQ=100 CTL= ACK=301 DATA=10 Should_ACK=111 SEQ=301