RFC 793State machine study

3-way handshakePage 31, Figure 7

3-way handshake

TCP A TCP BSEQ=NA

Page:31Figure. 7

1. CLOSED LISTEN

SEQ=NASEQ=300Should_ACK=NA Should_ACK=NA

3-way handshake

TCP A TCP BSEQ=NA SEQ=300

Page:31Figure. 7

1. CLOSED LISTEN2. SYN-SENT --> <SEQ=100><CTL=SYN> --> SYN-RECEIVED

SEQ=100

SEQ=100 CTL=SYNACK= DATA=

Should_ACK=NA Should_ACK=NAShould_ACK=101

3-way handshake

TCP A TCP BSEQ=300

Page:31Figure. 7

2. SYN-SENT --> <SEQ=100><CTL=SYN> --> SYN-RECEIVED3. ESTABLISHED <-- <SEQ=300><ACK=101><CTL=SYN,ACK> <-- SYN-RECEIVED

SEQ=100 CTL=SYNACK= DATA=

SEQ=300 CTL=SYNACK=101 DATA=

SEQ=100 Should_ACK=NA Should_ACK=101Should_ACK=301SEQ=101

3-way handshake

TCP A TCP BSEQ=300

Page:31Figure. 7

3. ESTABLISHED <-- <SEQ=300><ACK=101><CTL=SYN,ACK> <-- SYN-RECEIVED4. ESTABLISHED --> <SEQ=101><ACK=301><CTL=ACK> --> ESTABLISHED

SEQ=300 CTL=SYNACK=101 DATA=

SEQ=101 Should_ACK=101Should_ACK=301

SEQ=100 CTL=ACK=301 DATA=

Should_ACK=101SEQ=301

3-way handshake

TCP A TCP BSEQ=301

Page:31Figure. 7

4. ESTABLISHED --> <SEQ=101><ACK=301><CTL=ACK> --> ESTABLISHED5. ESTABLISHED --> <SEQ=101><ACK=301><CTL=ACK><DATA> --> ESTABLISHED

SEQ=101 Should_ACK=101Should_ACK=301

SEQ=100 CTL=ACK=301 DATA=

SEQ=100 CTL=ACK=301 DATA=10

Should_ACK=111SEQ=301