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Re: [tcpm] I-D Action: draft-nishida-tcpm-agg-syn-ext-00.txt

Matthew Luckie <mjl@caida.org> Mon, 08 February 2021 22:15 UTC

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Date: Tue, 09 Feb 2021 11:15:45 +1300
From: Matthew Luckie <mjl@caida.org>
To: "Scheffenegger, Richard" <rs.ietf@gmx.at>
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Subject: Re: [tcpm] I-D Action: draft-nishida-tcpm-agg-syn-ext-00.txt
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Hi Richard,

On Mon, Feb 08, 2021 at 10:46:45PM +0100, Scheffenegger, Richard wrote:
> Hi Yoshi,
> 
> Sorry to nitpick - in your draft, you mention that some hosts reflect
> back unknown tcp options, which is why you are using different GID
> mappings between SYN and SYN,ACK.
> 
> I did read about this behavior concerning TCP header flags / reserved
> bits - but have not come across a paper where this behavior is described
> for unknown TCP options (or I may have missed that aspect in the various
> studies around TCP option investigations done by MPTCP and other groups).

There is some discussion of systems that seem to reflect TCP options here:

http://blog.multipath-tcp.org/blog/html/2018/12/19/which_servers_use_multipath_tcp.html

Matthew

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