Re: [multipathtcp] potential MPTCP proxy charter item

Joe Touch <touch@isi.edu> Mon, 07 November 2016 16:34 UTC

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From: Joe Touch <touch@isi.edu>
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Date: Mon, 7 Nov 2016 08:33:55 -0800
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References: <CCD1A987-0F3C-4775-8B0E-5232965E7E22@nokia.com> <22907_1476946228_58086934_22907_5464_1_a7bca8d2-7656-4ff0-9f01-cf307f017148@OPEXCLILM42.corporate.adroot.infra.ftgroup> <57543A7A-1542-4C60-A5D3-E1658354BE5A@tik.ee.ethz.ch> <73a1c0dd64a843a5baa645d960c82886@rew09926dag03b.domain1.systemhost.net> <b8bfd5c6-21eb-4c4f-879a-851c3a71792a@OPEXCLILM31.corporate.adroot.infra.ftgroup> <56CE164A-9A62-4B57-9CFF-33DBD45BA8B2@gmail.com> <787AE7BB302AE849A7480A190F8B933009D9CA84@OPEXCLILMA3.corporate.adroot.infra.ftgroup> <85D52AE4-FE5F-4977-8927-6BDB72614D07@gmail.com> <787AE7BB302AE849A7480A190F8B933009DAAA88@OPEXCLILMA3.corporate.adroot.infra.ftgroup> <D2630820-7586-4361-A626-3278F22C319C@gmail.com> <B7D8197F-D833-41BB-A4A4-D6F31A3B8993@tik.ee.ethz.ch> <4fceb7e5-a0b0-d4d2-8669-fad0df59095d@uclouvain.be> <C0212561-63DA-4578-9795-928B51F2A71B@tik.ee.ethz.ch> <c93d9d6b-f46b-2b11-da6b-a308159ef7c0@isi.edu> <00ba6ab8-8fbf-ab19-b996-b84b87ad5520@isi.edu>
To: =?utf-8?Q?Mirja_K=C3=BChlewind?= <mirja.kuehlewind@tik.ee.ethz.ch>, Olivier.Bonaventure@uclouvain.be
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Subject: Re: [multipathtcp] potential MPTCP proxy charter item
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More specifically - see section 4.2.2.5 of rfc1122.

Joe

> On Nov 7, 2016, at 8:07 AM, Joe Touch <touch@isi.edu> wrote:
> 
> Oh - a quick followup.
> 
> If you have an option that "poisons" the connection if not confirmed (as
> would using long EDO inside the SYN), then you have to retry without
> that option. That is *possible*, but there's another problem.
> 
> RFC793 defines options as optional. Making any option mandatory would
> require updating RFC793. That sort of change is exactly why long EDO
> (actually extending the option space, rather than declaring the
> capability) is currently prohibited in EDO.
> 
> Joe
> 
> 
>> On 11/7/2016 7:56 AM, Joe Touch wrote:
>> 
>>> On 11/7/2016 7:42 AM, Mirja Kühlewind wrote:
>>> Do you mean the MCP forwards the original SYN (and basically does nothing if the server supports MPTCP) or does the MCP terminate the TCP connection and start a new TCP connection with MP_CAPABLE towards the server?
>>> 
>>> Mirja
>> If you're OK with needing to terminate a failed option exchange, then it
>> might be possible to use EDO in the SYN in its current form.
>> 
>> TCPM decided to prohibit that in the general case, but I could ask them
>> to allow that in very limited environments (but it could NEVER be
>> default on).
>> 
>> Note - the use cases I'm hearing appear to assume very strong knowledge
>> about the other end of the connection and the path. In that case, you
>> probably can skip most - if not all - of the 'negotiation' options and
>> just start using them during the SYN too. However, if you say "no, we
>> need to confirm", then you would not be able to use EDO inside the SYN.
>> 
>> Joe