Client Server
-------- SYN J -------->
<--- SYN K, ACK J+1 ----
------- ACK K+1 ------->

During TCP connection establishment (above), the third segment is an ACK
from the client to the server. What is the sequence number in that segment?
Is it J or J+1 or 0 or some other value?

"barcaroller" <barcaroller@music.net> wrote:
> Client Server
> -------- SYN J -------->
> <--- SYN K, ACK J+1 ----
> ------- ACK K+1 ------->
>
> During TCP connection establishment (above), the third segment is an
> ACK from the client to the server. What is the sequence number in
> that segment? Is it J or J+1 or 0 or some other value?

Figure 7 in RFC0793 shows the same handshake, but with the additional
detail needed to answer your question. The sequence number in the third
segment is shown as J+1.

In general, any TCP segment containing a set FIN flag, a set SYN flag,
and/or data must advance the sequence number. Any segment void of all three
of those sequence-number-consuming aspects should contain the current
sequence number.

barcaroller wrote:
> Client Server
> -------- SYN J -------->
> <--- SYN K, ACK J+1 ----
> ------- ACK K+1 ------->
>
> During TCP connection establishment (above), the third segment is an ACK
> from the client to the server. What is the sequence number in that segment?
> Is it J or J+1 or 0 or some other value?
>
>
>
>

Here is a question for you ...... when is the homework or takehome exam
due ?

barcaroller дµÀ:
> Client Server
> -------- SYN J -------->
> <--- SYN K, ACK J+1 ----
> ------- ACK K+1 ------->
>
> During TCP connection establishment (above), the third segment is an ACK
> from the client to the server. What is the sequence number in that segment?
> Is it J or J+1 or 0 or some other value?
>
>
>
>
I use tcpdump to capture a FTP link.and the result is J + 1.

--

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