On Tue, Mar 27, 2018 at 11:18 AM, Christoph Paasch <cpaasch@apple.com> wrote:
It also would allow us to expose subflows as file-descriptors to the
user-space. That way the user-space can do setsockopt, getsockopt,... on the
subflows. An idea that came up in the past when we were thinking on how to
expose an MPTCP API that allows apps to control certain things on the
subflows.

+1 to this since it will allow client platforms to use setsockopt to, for example, bind subflows to interfaces (e.g., with SO_BINDTODEVICE, or with SO_MARK as used by Android).