I'd agree to Joe's proposal "Although this protocol could benefit from extended SYN space, e.g., to support in-band key coordination, future TEPs should expect to use only the currently available space."
Michael (chair hat off) ________________________________________ From: Joe Touch <to...@isi.edu> Sent: Monday, February 6, 2017 17:34 To: David Mazieres expires 2017-05-06 PDT; Scharf, Michael (Nokia - DE); Holland, Jake; tcpinc@ietf.org Cc: t...@ietf.org Subject: Re: [tcpm] [tcpinc] WGLC for draft-ietf-tcpinc-tcpeno FWIW: On 2/5/2017 5:26 AM, David Mazieres wrote: > "Scharf, Michael (Nokia - DE)" <michael.sch...@nokia.com> writes: > >> While TCPM discusses large SYN options (for a long time already), all >> known solutions have downsides. I do not believe that a non-TCPM >> document should speculate on the feasibility solutions. > Michael, what do you think of the new proposed wording? > > Various proposals exist to increase the maximum space for options in > the TCP header. Though these proposals are highly experimental-- The non-SYN extension is currently a WG document and intended for standards-track. > particularly those that apply to SYN segments The SYN extension proposals all have significant known issues and are both highly experimental and difficult to deploy. > --TCP-layer encryption > could significantly benefit from the availability of increased SYN > option space. It might be useful to differentiate between the potential use of non-SYN vs. SYN space. You should be more explicit that "Although this protocol could benefit from extended SYN space, e.g., to support in-band key coordination, future TEPs should expect to use only the currently available space." IMO, the following is speculative and not useful: > In particular, if future TEPs can perform key > agreement by embedding public keys or Diffie-Hellman parameters > within suboption data, it will simplify protocols and reduce the > number of round trips required for connection setup. With large > options, the 32-byte limit on length bytes could prove insufficient. > This draft intentionally aborts TCP-ENO if a length byte is followed > by an octet in the range 0x00-0x9f. The following appears to direct TCPM docs to update this doc, which is not appropriate. If there is a SYN extension, it is much more likely to be a stand-alone doc to update RFC793 and other docs would individually update protocols that might benefit from that space. > Any document updating TCP's > option size limit can also define the format of larger suboptions by > updating this draft to assign meaning to such currently undefined > byte sequences. ... > > Our goal is not to second-guess TCPM, but rather to provide TCPM with a > data point that they have a "customer" for large SYN options in the > unlikely event that some proposal is ever deemed realistic. I could > make the wording even stronger, as in: > > These proposals are highly experimental--with those that apply to SYN > segments particularly unlikely to be adopted any time soon--but > TCP-layer encryption could significantly benefit from the > availability of increased SYN option space. Actually, the above is much more useful (IMO), but most of the rest of the paragraph can be omitted. Joe > > But that could be seen as second-guessing TCPM in the other > direction--telling TCPM we *don't* expect them to standardize large SYN > options anytime soon. (Of course, it's true that I don't expect them to > do that, but it might not be my place to say so in an RFC unless you > sign off on the language...) > > As always, concrete suggestions on wording are appreciated. > > Thanks, > David > > _______________________________________________ > tcpm mailing list > t...@ietf.org > https://www.ietf.org/mailman/listinfo/tcpm _______________________________________________ Tcpinc mailing list Tcpinc@ietf.org https://www.ietf.org/mailman/listinfo/tcpinc
