Re: [tcpm] 793bis ready to go?

Michael Tuexen <Michael.Tuexen@lurchi.franken.de> Sun, 21 February 2021 19:15 UTC

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From: Michael Tuexen <Michael.Tuexen@lurchi.franken.de>
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Date: Sun, 21 Feb 2021 20:15:30 +0100
Cc: tcpm IETF list <tcpm@ietf.org>, Markku Kojo <kojo=40cs.helsinki.fi@dmarc.ietf.org>
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To: Joseph Touch <touch@strayalpha.com>
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Subject: Re: [tcpm] 793bis ready to go?
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> On 21. Feb 2021, at 19:38, Joseph Touch <touch@strayalpha.com> wrote:
> 
> On Feb 20, 2021, at 1:53 PM, Michael Tuexen <michael.tuexen@lurchi.franken.de> wrote:
>> 
>> 
>> 
>>> On 20. Feb 2021, at 22:37, Joseph Touch <touch@strayalpha.com> wrote:
>>> 
>>> Even if you prefer the FreeBSD variant, the text below doesn’t appear to fix this; it will end up sending the SYN-ACK of the received data *and a second ACK* at the end of the sixth step.
>> I think the idea of Richard is that if the text is
>> 
>>         If SND.UNA > ISS (our SYN has been ACKed), change the
>>         connection state to ESTABLISHED, form an ACK segment
>>         <SEQ=SND.NXT><ACK=RCV.NXT><CTL=ACK>
>>         and should send it.
>> 
>> Then NOT following the should, but only send the ACK at the end of step 6.
>> Wouldn't that work?
> 
> FWIW, I think the case of combining the bare ACK with the ACK of the received SYN-ACK data is already covered in the sixth step below in the following text:
> 
>         This acknowledgment should be piggybacked on a segment being
>         transmitted if possible without incurring undue delay.
> 
I agree, this covers it. But it would be good to have it a bit more explicit.
> 
> If this needs to be made more explicit, here’s my suggestion:
> 
> OLD:
> 
>         If SND.UNA > ISS (our SYN has been ACKed), change the connection
>         state to ESTABLISHED, form an ACK segment
> 
>           <SEQ=SND.NXT><ACK=RCV.NXT><CTL=ACK>
> 
>         and send it.  Data or controls which were queued for
>         transmission may be included.  If there are other controls or
>         text in the segment then continue processing at the sixth step
>         below where the URG bit is checked, otherwise return.
> 
> 
> 
> NEW:
> 
>         If SND.UNA > ISS (our SYN has been ACKed), change the connection
>         state to ESTABLISHED, form an ACK segment
> 
>           <SEQ=SND.NXT><ACK=RCV.NXT><CTL=ACK>
> 
>         Data or controls which were queued for
> 
>         transmission MAY be included in this segment.  If there are no 
> 	other controls or text in the segment then send the ACK segment 
Maybe:
         other controls or text in the received segment then send the ACK segment 
> 	and return. Otherwise, continue processing at the sixth step below 
> 	where the URG bit is checked, either sending the ACK segment now or 
> 	piggybacking it with the response from that continued processing
> 	(as noted therein).
I like your proposal (maybe with the above suggestion).

Best regards
Michael
> 
> Joe