Re: I-D Action: draft-ietf-tcpm-1323bis-02.txt

> Also, for this issue that Alexander brings up, the
> timestamp has to be changing between ACKs. If the
> timestamp hasn't changed between the re- ordered
> ACKs, then the "SEG.TSval >= TS.recent" check will
> succeed. Generally, the TS clock shouldn't be
> ticking that often, if it is changing with every
> ACK then it might be going faster than it needs to.
>
> So, this issue only occurs when ACKs are re-ordered,
> *and* the Timestamp clock has ticked between the
> reordered ACKs. I'm thinking that 1323bis should
> just note that this situation does exist.
>
> What does everyone else think? Shall we leave the
> text as is and just document this edge case, or do
> people disagree with me and feel that this is a
> real problem that needs to be addressed, and is
> more important than the problems that the original
> change fixes?
>
> -David

> -----Original Message-----
> From: David Borman [mailto:dab@...]
> Sent: Freitag, 18. Mai 2012 19:38
> To: Scheffenegger, Richard
> Cc: tcpm@... Extensions WG
> Subject: Re: [tcpm] I-D Action: draft-ietf-tcpm-1323bis-02.txt
>
> Hi Richard,
> Thanks for doing the legwork on bringing this document into the modern
> age, the original nroff code was getting a bit old. :-)
>
> The pseudo code needs to be updated to match the main body of the
> document.  Specifically, it has:
>
>             Check whether the segment contains a Timestamps option and
>             bit Snd.TS.OK is on.  If so:
>
>                If SEG.TSval < TS.Recent and the RST bit is off, then
>                test whether connection has been idle less than 24 days;
>                if all are true, then the segment is not acceptable;
>                follow steps below for an unacceptable segment.
>
>                If SEG.SEQ is equal to Last.ACK.sent, then save SEG.TSval
>                in variable TS.Recent.
>
>             There are four cases for the acceptability test for an
>             incoming segment:
>
> The second case needs to be changed to:
>
>                If SEG.SEQ is less than or equal to Last.ACK.sent, then save SEG.TSval
>                in variable TS.Recent.
>
> -David Borman
>
>
> On May 18, 2012, at 11:14 AM, Internet-Drafts@... wrote:
>
> >
> > A New Internet-Draft is available from the on-line Internet-Drafts
> directories. This draft is a work item of the TCP Maintenance and Minor
> Extensions Working Group of the IETF.
> >
> > Title           : TCP Extensions for High Performance
> > Author(s)       : David Borman
> >                          Bob Braden
> >                          Van Jacobson
> >                          Richard Scheffenegger
> > Filename        : draft-ietf-tcpm-1323bis-02.txt
> > Pages           : 45
> > Date            : 2012-05-18
> >
> >   This memo presents a set of TCP extensions to improve performance
> >   over large bandwidth*delay product paths and to provide reliable
> >   operation over very high-speed paths.  It defines TCP options for
> >   scaled windows and timestamps, which are designed to provide
> >   compatible interworking with TCP's that do not implement the
> >   extensions.  The timestamps are used for two distinct mechanisms:
> >   RTTM (Round Trip Time Measurement) and PAWS (Protection Against
> >   Wrapped Sequences).  Selective acknowledgments are not included in
> >   this memo.
> >
> >   This memo updates and obsoletes RFC 1323.
> >
> >
> > A URL for this Internet-Draft is:
> > http://www.ietf.org/internet-drafts/draft-ietf-tcpm-1323bis-02.txt
> >
> > Internet-Drafts are also available by anonymous FTP at:
> > ftp://ftp.ietf.org/internet-drafts/
> >
> > This Internet-Draft can be retrieved at:
> > ftp://ftp.ietf.org/internet-drafts/draft-ietf-tcpm-1323bis-02.txt
> >
> > The IETF datatracker page for this Internet-Draft is:
> > https://datatracker.ietf.org/doc/draft-ietf-tcpm-1323bis/
> >
> > _______________________________________________
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