Simultaneous Open

Simultaneous Open - Reg

"Udaya kumar" <uday@qpackets.com> Mon, 22 April 2002 04:43 UTC

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From: "Udaya kumar" <uday@qpackets.com>
To: <tcp-impl@grc.nasa.gov>
Subject: Simultaneous Open - Reg
Date: Mon, 22 Apr 2002 10:13:26 +0530
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Hi

    I have a query regarding simultaneous open in TCP.

    The response to a SYN segment in the SYN_SENT state is to send a SYN,ACK carrying the old sequence number(i.e seq. no of the SYN segment sent earlier). Ref -> rfc793 &&  rfc1122. If the response is such,  then the SYN,ACK segment would be dropped at the receving side due to sequence number check. Hence connection cannot be established.


In our imlpementation it is noted that the TCP stack sends a simple ACK segment with the next sequence number instead of the SYN,ACK mentioned above. This simple ACK with incremented seq. number would definetly be accepted at the other end and the two sides will go to established state.

I request for a clarification in this regard as to which approach is correct and is there any reference to this issue in the rfcs other than 793 and 1122.

thanks
uday