Re: [tsvwg] The List (of application-layer desired features)

[William Chan (陈智昌) <[e-mail]>]

On Wed, Aug 28, 2013 at 9:41 PM, Michael Tuexen <
[e-mail]> wrote:

> On Aug 28, 2013, at 3:34 PM, William Chan (陈智昌) <[e-mail]>
> wrote:
>
> > On Wed, Aug 28, 2013 at 7:53 PM, Michael Welzl <[e-mail]>
> wrote:
> >
> > On 28. aug. 2013, at 11:53, William Chan (陈智昌) wrote:
> >
> >> On Aug 28, 2013 4:01 PM, "Michael Welzl" <[e-mail]> wrote:
> >> >
> >> > Hi,
> >> >
> >> > I agree 100% with Michael Tuexen here... just one thing, in line:
> >> >
> >> >
> >> >>> You're right, SCTP is non-deployable, which makes it a non-starter.
>  SCTP also does not address handshake issues or TLS issues.
> >> >>
> >> >> I agree that SCTP over IP can't be deployed now due to missing NAT
> support.
> >> >
> >> >
> >> > Indeed that's not an argument against SCTP/UDP/IP, but I also wonder
> why, instead of saying "can't be deployed", people don't just go ahead and
> use it whenever it's there and works, with a fall-back to TCP? This could
> be done with (this version of) Happy Eyeballs:
> >> > http://tools.ietf.org/html/draft-wing-tsvwg-happy-eyeballs-sctp-02
> >> >
> >> > Good reasons against doing this are... what? Anyone?
> >>
> >> Implementation usefulness. Why bother adding code that barely gets used
> (and that is unlikely to improve in the near future), adds complexity, code
> bloat, etc...?
> >>
> > Fair point. That's why I think the OS should in fact do Happy Eyeballs
> for you!
> >
> >
> > I'm not sure if you're trolling me. In case you aren't, you may want to
> look at the graph at:
> http://gs.statcounter.com/#os-ww-monthly-201207-201307. Windows XP
> (released in 2001) is still around 20% of browser usage. If you have the
> ability to get Microsoft to backport SCTP/IP onto their XP stack, I'd love
> to know. We're not going to ignore large segments of our user base when we
> could use UDP and deploy for all relevant OSes. That may be acceptable for
> some applications, but not for the browser I work on.
> You can build SCTP in your browser and run it on top of UDP. This is what
> is done
> in RTCWeb. They use SCTP over DTLS over UDP with SCTP and DTLS running in
> the
> application layer. This is available in recent versions of Firefox and
> running
> on Windows XP...
>

You may have missed the fact that Michael Welzl was talking about SCTP/IP
and I was responding to that. You may also have missed my note below about
SCTP over UDP where I said: "SCTP/UDP has a much higher likelihood of
usefulness."

Cheers.


>
> Best regards
> Michael
> >
> > This is why Roberto said:
> > """
> > Wide, "safe" deployment
> > """
> >> SCTP/UDP has a much higher likelihood of usefulness. But as Roberto has
> mentioned, it still has deficiencies, mostly around RTTs (connection + DTLS
> setup). If they can be fixed, great. Let's do it.
> >>
> > Why shouldn't it be possible to fix SCTP to do whatever you want? Anyway
> it sounds to me like a simpler approach than building a whole new protocol.
> Of course, SCTP++ isn't the nicest acronym...  then again, RTMFP isn't
> either, if you ask me, sounds almost like RTFM...  QUIC is great though!
> >
> > I have no attachments to the protocol name or frame format or whatever.
> Look at what we're doing in HTTP/2 which was inspired by SPDY but now has
> undergone substantial changes. We're serious about this. As long as the
> transport provides all the features we need, we'll use it. This
> conversation got started because tsvwg asked httpbis what the application
> layer wants from the transport. We're telling you. I think the constructive
> next step is for tsvwg folks to ask for clarification on any requirement
> they don't understand, discuss whether or not the requirements are
> reasonable, and discuss what may need to be done to address them.
> >
> >
> > Cheers,
> > Michael
> >
> >
>
>