Subject: Re: [tcpm] I-D Action: draft-borman-tcpm-tcp4way-00.txt

From: David Borman <[email-masked]>
Date: Fri, 24 Oct 2014 11:21:07 -0500

I’ve just posted an update to the TCP Four-Way handshake document.

1) I changed the name of the document to include tcpm: draft-dborman-tcpm-tcp4way-00.txt

2) I’ve added text that any implementation that indicates support for the Four-Way handshake is also indicating that it properly handles unknown TCP options, as per RFC 1122.  We keep dancing around that issue, and this gives us a way to stop worrying about it anymore, and
a way for an implementation to know for sure that it isn’t talking to a legacy TCP implementation.

3) I’ve added a preliminary section to discuss specific TCP options

4) I’ve added text about the TS option to clarify RFC 7323, that it is the presence of TSopt in both a sent and received packet with the SYN bit that enables the option, i.e. it is not limited to the specific instance of the <SYN> and <SYN,ACK> packets of the three-way handshake.

And something entirely new:

5) I’ve added a new TCP option, the Unknown Option option.  Currently, the primary way to determine that the other side of the connection doesn’t support a specific option is by lack of response to that option, because it silently ignores it.  The Unknown Option option provides a mechanism where a TCP can inform the other side that it does not understand or support any given option for a connection.  This can be very useful for sending TCP options in non-SYN packets, especially if the option is not explicitly enabled through the SYN exchange, or it is a one-way option.  UTO comes to mind.

The document needs more work, but I wanted to get an update out today, before Mondays submission cutoff.

			-David Borman

> On Oct 24, 2014, at 11:01 AM, [email-masked] wrote:
> 
> 
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
> 
> 
>        Title           : TCP Four-Way Handshake
>        Author          : David Borman
> 	Filename        : draft-borman-tcpm-tcp4way-00.txt
> 	Pages           : 21
> 	Date            : 2014-10-24
> 
> Abstract:
>   One of the limitations of TCP is that it has limited space for TCP
>   options, only 40 bytes.  Many mechanisms have been proposed for for
>   extending the TCP option space, but the biggest challenge has been to
>   get additional option space in the initial SYN packet.
> 
>   This memo presents a optional four-way TCP handshake to allow
>   extended option space to be used in SYN packets in both directions.
> 
> 
> The IETF datatracker status page for this draft is:
> https://datatracker.ietf.org/doc/draft-borman-tcpm-tcp4way/
> 
> There's also a htmlized version available at:
> http://tools.ietf.org/html/draft-borman-tcpm-tcp4way-00
> 
> 
> Please note that it may take a couple of minutes from the time of submission
> until the htmlized version and diff are available at tools.ietf.org.
> 
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/
> 
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