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Recovery from old Duplicate SYN
TCP A TCP BSEQ=NA
Page:33Figure. 9
1. CLOSED LISTEN
SEQ=NASEQ=300Should_ACK=NA Should_ACK=NA
SEQ=90 CTL=SYNACK= DATA=
Recovery from old Duplicate SYN
TCP A TCP BSEQ=NA SEQ=300
Page:33Figure. 9
SEQ=100
SEQ=100 CTL=SYNACK= DATA=
Should_ACK=NA Should_ACK=NA
SEQ=90 CTL=SYNACK= DATA=
1. CLOSED LISTEN2. SYN-SENT --> <SEQ=100><CTL=SYN> ...
Recovery from old Duplicate SYN
TCP A TCP BSEQ=300
Page:33Figure. 9
Should_ACK=NA Should_ACK=NA
SEQ=90 CTL=SYNACK= DATA=
2. SYN-SENT --> <SEQ=100><CTL=SYN> ...3. (duplicate) ... <SEQ=90><CTL=SYN> --> SYN-RECEIVED
SEQ=100 Should_ACK=91
SEQ=100 CTL=SYNACK= DATA=
Recovery from old Duplicate SYN
TCP A TCP BSEQ=300
Page:33Figure. 9
Should_ACK=NA
3. (duplicate) ... <SEQ=90><CTL=SYN> --> SYN-RECEIVED4. SYN-SENT <-- <SEQ=300><ACK=91><CTL=SYN,ACK> <-- SYN-RECEIVED
SEQ=100 Should_ACK=91
SEQ=90 CTL=SYNACK= DATA=
SEQ=300 CTL=SYNACK=91 DATA=
?
SEQ=100 CTL=SYNACK= DATA=
Recovery from old Duplicate SYN
TCP A TCP BSEQ=300
Page:33Figure. 9
Should_ACK=NA
4. SYN-SENT <-- <SEQ=300><ACK=91><CTL=SYN,ACK> <-- SYN-RECEIVED5. SYN-SENT --> <SEQ=91><CTL=RST> --> LISTEN
SEQ=100 Should_ACK=91
?
SEQ=100 CTL=SYNACK= DATA=
SEQ=91 CTL=RSTACK= DATA=
Should_ACK=NASEQ=400
SEQ=300 CTL=SYNACK=91 DATA=
Recovery from old Duplicate SYN
TCP A TCP B
Page:33Figure. 9
Should_ACK=NA
5. SYN-SENT --> <SEQ=91><CTL=RST> --> LISTEN6. ... <SEQ=100><CTL=SYN> --> SYN-RECEIVED
SEQ=100
SEQ=100 CTL=SYNACK= DATA=
Should_ACK=NASEQ=400 Should_ACK=101
Recovery from old Duplicate SYN
TCP A TCP B
Page:33Figure. 9
Should_ACK=NA
6. ... <SEQ=100><CTL=SYN> --> SYN-RECEIVED7. SYN-SENT <-- <SEQ=400><ACK=101><CTL=SYN,ACK> <-- SYN-RECEIVED
SEQ=100 SEQ=400
SEQ=400 CTL=SYNACK=101 DATA=
Should_ACK=101Should_ACK=401SEQ=101
SEQ=100 CTL=SYNACK= DATA=
Recovery from old Duplicate SYN
TCP A TCP B
Page:33Figure. 9
Should_ACK=401
7. SYN-SENT <-- <SEQ=400><ACK=101><CTL=SYN,ACK> <-- SYN-RECEIVED8. ESTABLISHED --> <SEQ=101><ACK=401><CTL=ACK> --> ESTABLISHED
SEQ=101 SEQ=400 Should_ACK=101
SEQ=400 CTL=SYNACK=101 DATA=
SEQ=101 CTL=ACK=401 DATA=
Should_ACK=101SEQ=401