[tcpm] Comments on draft-kang-tcpm-subtype-capability-exchange-00

[Martin Duke <[e-mail]>]

I can't speak to the problems subtype mismatches are causing, if any, but I
do like the idea of negotiation extension of new subtypes without having to
roll whole new MPTCP versions.

I wonder if we could save some bits by assuming that 0x0-0x7 will be
supported by all MPTCP implementations and omitting them from this field.

The location of the OptionSupported field probably has to change along with
other details of Figure 2. If I understand correctly, OptionSupported has
to begin with the 5th byte, as this first goes out with the SYN where the
entire (original) option is 4 bytes. Which means, we're relying on the
length field to indicate this is not like other MP-CAPABLE options. I'm not
sure this interoperability model is fully thought out.