Paul Moore [off-list ref] wrote:

I'm not very well versed in MPTCP, but this *seems* okay to me, minus
the else-crud chunk.  Just to confirm my understanding, while MPTCP
allows one TCP connection/stream to be subdivided and distributed
across multiple interfaces, it does not allow multiple TCP streams to
be multiplexed on a single connection, yes?

Its the latter.  The application sees a TCP interface (socket), but
data may be carried over multiple individual tcp streams on the wire.