Re: [rtcweb] [rmcat] Catching up on diffserv markings

[Justin Uberti <[e-mail]>]

Right; I checked and while IP_RECVTOS isn't exposed to Java, I think you
can setsockopt/recvmsg to get the ECN data when writing to the Android NDK.

On Fri, Oct 23, 2015 at 1:34 AM, Harald Alvestrand <[e-mail]>
wrote:

> ECN markings are just a byte in the IP header.
>
> The brutal way to do this is to get your packets as raw packets, and
> doing UDP processing yourself.
>
> The less brutal way on Linux is to use setsockopt(IP_RECVTOS) ("since
> Linux 2.2" according to "man 7 ip"). There's a 2012 FreeBSD code example
> from Michael Tuexen here:
>
> http://lists.freebsd.org/pipermail/freebsd-net/2012-June/032519.html
>
> (Linux and FreeBSD may not count as "widely deployed" on the desktop,
> but Linux wrapped up as Android is a fairly frequent player in the
> mobile space.)
>
> Den 22. okt. 2015 21:54, skrev Justin Uberti:
> > At present I'm not aware of any widely-deployed OS where an app can read
> > the received ECN markings.
> >
> > iOS9 added support for this within the kernel, and it's used for TCP,
> > but not exposed to userspace. There is an open Radar bug asking for this
> > info to be exposed to userspace.
> >
> > FWIW, Chrome supports setting the DSCP markings if you set a magic
> > parameter. But it's not on by default, mainly because we've never done
> > the auditing necessary to ensure this doesn't randomly break in various
> > dimly-lit parts of the internet.
> >
> > On Thu, Oct 22, 2015 at 2:13 AM, Colin Perkins <[e-mail]
> > <mailto:[e-mail]>> wrote:
> >
> >>     On 22 Oct 2015, at 08:48, Pal Martinsen (palmarti)
> >>     <[e-mail] <mailto:[e-mail]>> wrote:
> >>
> >>
> >>>     On 21 Oct 2015, at 18:10, Harald Alvestrand <[e-mail]
> >>>     <mailto:[e-mail]>> wrote:
> >>>
> >>>     Den 21. okt. 2015 17:51, skrev Dave Taht:
> >>>>     I unsubscribed from rmcat and rtcweb groups a while back after I
> got
> >>>>     overloaded, and appear.in <http://appear.in> started working so
> >>>>     well, (for both ipv6 and
> >>>>     ipv4! I use it all day long now!), to focus on finishing up the
> new
> >>>>     "cake" qdisc/shaper/aqm/QoS system, among other things.
> >>>>
> >>>>     http://www.bufferbloat.net/projects/codel/wiki/CakeTechnical
> >>>>
> >>>>     Cake is now entering the testlab, and among other things, it has
> >>>>     support for the diffserv markings discussed in the related, now
> >>>>     concluded dart wg, but in ways somewhat different from that
> imagined
> >>>>     there. We have not got any good code in our testbeds yet to test
> >>>>     videoconferencing behavior, and we could use some, although it
> does
> >>>>     look like we can drive firefox with some remote control stuff
> with a
> >>>>     fixed video playback now....
> >>>>
> >>>>     Five questions:
> >>>>
> >>>>     1) Has anyone implemented or tested putting voice and video on two
> >>>>     different 5-tuples in any running code out there?
> >>>
> >>>     All VC systems I know of except WebRTC-based ones do it, AFAIK.
> >>>     It’s putting them on the same that's unusual.
> >>>
> >>     That sounds like the world I am living in as well.
> >>
> >>
> >>>>     2) How about diffserv markings in general? Do any browsers or
> webrtc
> >>>>     capable software support what was discussed way back when?
> >>>
> >>>     I know Hangouts did something like that internally, on the
> controlled
> >>>     network. But not according to spec.
> >>>
> >>>>     3) Were diffserv marking changes eventually allowed on the same
> >>>>     5-tuple?
> >>>
> >>>     Yes, with caveats. draft-ietf-tsvwg-rtcweb-qos has the table.
> >>>
> >>>>     4) Did the ECN support that was originally in one draft or another
> >>>>     ever make it into any running code?
> >>>
> >>>     I don't know. I think we lost it from the docs.
> >>>
> >>>>     (yea, apple plans to turn on ecn universally in their next OS!)
> >>>>
> >>     So how would ECN work on UDP? I do not think the necessary bits
> >>     from the IP header are available for the application to do
> >>     anything. I do think Linux supports this, have not tested.
> >>
> >>     And what about the network, would it support UDP when setting the
> >>     ECN bits? Probably a configuration related problem if not supported.
> >
> >     RFC 6679 describes how to use ECN with RTP on UDP, although as you
> >     say there are implementation difficulties on some platforms. I’m not
> >     sure whether there are implementations.
> >
> >
> >>>>     5)  What else did I miss in the past year I should know about?
> >>>
> >>>     For TCP and SCTP congestion controllers, we're back to one DSCP
> >>>     marking
> >>>     per flow, and resetting the congestion control state if DSCP
> marking
> >>>     changes.
> >>>
> >>
> >>     There is a new ICE wg. It was created so “network people” could
> >>     participate without the overhead of listening to the SDP related
> >>     discussions. (https://datatracker.ietf.org/wg/ice/charter/)
> >>
> >>     .-.
> >>     Pål-Erik
> >>
> >>>>
> >>>>     Feel free to contact me off list if these have already been
> >>>>     discussed.
> >>>>     I have totally lost track of the relevant drafts.
> >>>
> >>>     They're not finished still :-)
> >>>
> >>>>
> >>>>     Sincerely,
> >>>>
> >>>>     Dave Täht
> >>>>     I just lost five years of my life to making the edge
> >>>>     of the internet, and, wifi better.
> >>>>     And, now... the FCC wants to make my work illegal
> >>>>     for ordinary people to install.
> >>>>     https://www.gofundme.com/savewifi
> >>>>
> >>>>     _______________________________________________
> >>>>     rtcweb mailing list
> >>>>     [e-mail] <mailto:[e-mail]>
> >>>>     https://www.ietf.org/mailman/listinfo/rtcweb
> >>>>
> >>>
> >>>     _______________________________________________
> >>>     rtcweb mailing list
> >>>     [e-mail] <mailto:[e-mail]>
> >>>     https://www.ietf.org/mailman/listinfo/rtcweb
> >>
> >>     _______________________________________________
> >>     rtcweb mailing list
> >>     [e-mail] <mailto:[e-mail]>
> >>     https://www.ietf.org/mailman/listinfo/rtcweb
> >
> >
> >
> >     --
> >     Colin Perkins
> >     https://csperkins.org/
> >
> >
> >
> >
> >
> >
> >
> > _______________________________________________
> > rtcweb mailing list
> > [e-mail]
> > https://www.ietf.org/mailman/listinfo/rtcweb
> >
>
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