In the connection termination phase, suppose the FIN segment from the client-side contains data ranging from sequence no 100 to 200,

So will the ACK no from the server start from 201 or 202? Will the FIN flag consume 1 extra sequence number at the end, making the ACK no from server 202?

Or Will the sequence number consumed by FIN be 99, before the beginning of the data segment

  • This smells suspiciously like homework which is off-topic here...
    – Zac67
    Jan 25, 2022 at 6:51
  • @Zac67 nope it's not, it's self-doubt that I got while studying Foruzan. I already posted the detailed question here gateoverflow.in/370546/Self-doubt-cn#c370590 but I am not sure whether the answer I received is correct and also couldn't find the answer on the internet
    – Tushar
    Jan 25, 2022 at 7:13

1 Answer 1


Accroding to rfc793

TCP FIN occupies one byte in sequence number space and

the FIN is considered to occur after the last actual data octet in a segment in which it occurs

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