Because planet very way too much and even a given planet will have a wide
range of much greater than one our RTTs. TCP probably won't even work for
those kids of RTTs. What about a Lunar RTT instead of Interplanetary? The
moon is about 1.3 light seconds away, one way. That's a minimum of 2.6sec
RTT.

On Tue, Oct 20, 2015 at 12:32 PM, Kevin Darbyshire-Bryant <
kevin@darbyshire-bryant.me.uk> wrote:

> On 19/10/15 20:05, Sebastian Moeller wrote:
> > Hi,
> >
> > On October 19, 2015 10:24:01 AM CDT, Dave Taht <dave.taht@gmail.com>
> wrote:
> >> well, yes, but we can do it in the lab *this week*, before he takes
> >> the dingos on....
> > Good idea, als I am at A conference right now and will not find the time
> to make the changes to TC in time. I believe that cake should certainly A)
> set A reasonable target by default and B) still allow the user to
> explicitly request something else. Currently, I believe cake does only A)...
> >
> > Besteht Regards
> >         Sebadtian
> >
> >
>
> As an FYI:
>
>
> tc has a number of calculations for interval & target
>
> If an rtt is specified then target is 5% of interval with 1uS
> (microsecond!) and 5mS (millisecond) lower & upper bounds.
>
> The keyword predefined rtt values are:
>
> datacentre (100uS), lan (1mS), metro(10mS), regional(30mS),
> internet(100mS), oceanic(300mS), satellite(1000mS), interplanetary(1hour!)
> Corresponding targets are 5uS, 50uS, 500uS, 1.5mS and everything from
> internet onwards as a 5mS target.
>
> Although these are the values passed into cake from tc, that isn't the
> final story with regard to calculations as cake qdisc has some further
> sanity checks.
>
> If a link bandwidth is specified then the target is set to the max of
> '1.5 MTU's worth of link time' and the target value passed by tc.  The
> interval is set to max of '8 times the calculated target' and interval
> value passed by tc.
>
> So whilst tc supplies an rtt/interval and a 5% calculated target, cake
> itself will override this with sensible values if that makes sense for a
> 'slow' link.
>
> Kevin
>
>
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