Re: [multipathtcp] potential MPTCP proxy charter item

[<[e-mail]>]

Hi Joe, 

It is encouraging to consider using EDO, but the current approach we adopted for the MP_CONVERT option have the same failure risk as for introducing MPTCP at the scale of the Internet. 

Using EDO and/or defining MP_CONVERT as a TCP option exacerbates the failure vectors. Below a table that summarizes the failures that will be experienced for the MP_CONVERT case as a function if the design approach: 

   +------------------+-----------+-----------+-----------+------------+
   |                  | MP_CONVERT| MP_CONVERT| MP_CONVERT| MP_CONVERT |
   |                  |   MPTCP   |    TCP    |   MPTCP   | TCP Option |
   |                  |   Option  |   Option  |  Option + |   + EDO    |
   |                  |           |           |    EDO    |            |
   +------------------+-----------+-----------+-----------+------------+
   | MPTCP-unfriendly |    FAIL   |    FAIL   |    FAIL   |    FAIL    |
   |             path |           |           |           |            |
   +------------------+-----------+-----------+-----------+------------+
   |   EDO-unfriendly |     NA    |     NA    |    FAIL   |    FAIL    |
   |             path |           |           |           |            |
   +------------------+-----------+-----------+-----------+------------+
   | "Unknown TCP opt |     NA    |    FAIL   |     NA    |    FAIL    |
   |  ion"-unfriendly |           |           |           |            |
   |             path |           |           |           |            |
   +------------------+-----------+-----------+-----------+------------+

Cheers,
Med

> -----Message d'origine-----
> De : multipathtcp [mailto:[e-mail]] De la part de Joe
> Touch
> Envoyé : lundi 7 novembre 2016 16:56
> À : Mirja Kühlewind; [e-mail]
> Cc : [e-mail]
> Objet : Re: [multipathtcp] potential MPTCP proxy charter item
> 
> 
> 
> 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
> 
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