Re: [Int-area] Middleboxes to aid the deployment of MPTCP

[Joe Touch <[e-mail]>]

On 7/18/2017 4:05 PM, Olivier Bonaventure wrote:
>> Although I'm not averse to middleboxes as optional optimizations, I find
>> the proposed mechanisms aren't quite optional -- they inject option
>> information into the SYN data. That information would poison a
>> connection to a legacy receiver if (more to the point, when) that info
>> isn't removed by a proxy upstream of the receiver.
>
> This paragraph refers to earlier documents discussed in the MPTCP
> working group. The new design does not inject option information into
> the SYN data. It works like an application layer protocol that sends
> messages
> in the SYN by using the TFO option. There is no risk of poisoning.

OK, in that case:
- I'm still not averse to middleboxes that accelerate or enhance TCP
- IMO, TCP always needs to be able to fall back (which should be true now)
- but I remain concerned with "injection piggybacking"
    - even if this is restricted to option space, it increases the risk
of damaging an otherwise working connection
    - it flies in the face of TCP being E2E, and won't work with TCP-AO
or IPsec, which IMO means it can't be considered part of "TCP" at all

Joe