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Re: [tcpm] TCP Long Options - Why not as payload in SYNs?

Joe Touch <touch@ISI.EDU> Mon, 14 July 2008 21:57 UTC

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Date: Mon, 14 Jul 2008 14:57:33 -0700
From: Joe Touch <touch@ISI.EDU>
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Cc: tcpm@ietf.org, Caitlin Bestler <Caitlin.Bestler@neterion.com>
Subject: Re: [tcpm] TCP Long Options - Why not as payload in SYNs?
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Joe Touch wrote:
> Hi, all,
...
> AFAICT, SYN cookies are incompatible with long options, and yes, 
> rejecting them is the appropriate response if cookies are required for 
> all connections.

PS - one conclusion that we could draw here is that:

- we can show that there are NO versions of extending TCP options that 
are truly backward compatible
	i.e., that use a single SYN

- we can also show that there are NO versions of extending TCP options 
that are compatible with SYN cookies
	as long as the ISN is the same length, there's only so much
	place for state

Overall, that may imply that we cannot extend the TCP option space in a 
backward compatible way, at which point maybe we're back to Mark 
Allman's "let's double all the fields" proposal, i.e., a 'clean slate' 
TCPv2...

Joe


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