[tcpinc] New draft of TCP-ENO

[David Mazieres <[e-mail]>]

There is a new draft of TCP-ENO, here:

        https://datatracker.ietf.org/doc/draft-ietf-tcpinc-tcpeno/

There are very few changes from the previous draft, and most of them are
just cosmetic improvements or clarifications.  At the last meeting,
there was some discussion about whether the draft should allow a host to
send an ENO option with zero suboptions.  Upon further reflection, it
appeared there was really nothing in the existing draft that would
prevent such usage.  Hence, the only action we took on this question was
to clarify the situation by adding the following paragraph to the end of
section 4.6:

        A host MAY send a _vacuous_ SYN-form ENO option containing zero
        TEP identifier suboptions.  If either host sends a vacuous ENO
        option, it follows that there are no valid TEP identifiers for
        the connection and hence the connection must fall back to
        unencrypted TCP.  Hosts MAY send vacuous ENO options to indicate
        that ENO is supported but unavailable by configuration, or to
        probe network paths for robustness to ENO options.  However, a
        passive opener MUST NOT send a vacuous ENO option in a SYN-ACK
        segment unless there was an ENO option in the SYN segment it
        received.  Moreover, a passive opener's SYN-form ENO option MUST
        still include a global suboption with "b = 1", as discussed in
        Section 4.3.

David