Re: Refs or no refs

Jason Williams (streak@ccwf.cc.utexas.edu)
Mon, 27 Oct 1997 12:37:30 -0600 (CST)


On Mon, 27 Oct 1997, Rolf Hemmerling wrote:
> Yes, I often wonder if I have just one or two windows open why I don=B4t
> get my full 28.8 transmission speed for these two !!! Is there
> *anything* I can do by myself ? Probably not !

Not that I know of..Actually, if you have a 28.8kbps modem and are sending
around 15kbps, you can't receive the full rate that the others are sending
at (assuming they are sending at 15kbps as well)
Total sending for you =3D 15kbps
Total receive for you =3D 15kbps X 2 vids =3D 30kbps.
-------------------------------------------------
45kbps total required...neglecting the overhead of
the reflector (The overhead of Cornell reflectors is much more than that
of WP or Enhanced Reflectors).

Assuming the others are sending around 15kbps, you can get all of their
vid if you keep one window open and are sending around 15kbps. I've
always had problems with CU in opening up more than 2 windows. The
problem is made even worse if the people you are trying to see are using
color. Even with 2 windows open, the color window may never update.

> Note that I use the WP 2.1.1x version, and that there were comments on
> a certain windows-close bug of this version. I hope (?) that this bug is
> not the major reason for all my complains. In fact, I would like to
> hope that it is, so that shifting to another client versions gets me
> rid of the real problems with refs ! Currently, I stay with WP 2.1.1x on
> a trial base.

From=20Brian Godette's bugs page at
http://www.dimensional.com/~bgodette/techpage.html

v2.* does not turn off the received video stream from vid-windows that
you close by closing the window directly or by using the participants
list. The only way to turn off the video stream is to use the
"close-all-windows" command/button (closed eye on the button bar).
This is a bug that causes the majority of complaints about bad/broken
vid, this is also why it's strongly suggested to turn off auto-open of
remote video. This bug also seems to be an extention of the old
Cornell "null-assertion" problem with the participants list.

> Jason Williams wrote:
> > A lot of the problems can be attributed to=20
> > the "close all" bug of the White Pine 2.X clients on the PC. Try
> > hitting the close all button a few times and only opening up a few=20
> > vids at a time.
> I will have a try !
> > This seems to be fixed in the 3.X versions from what I can tell.
> But not with the new 2.1.2 version, as I assume !?!

No, 2.1.2 still has the problem. Too bad White Pine won't go back and fix
a few of the bugs in the 2.X versions.

> Well.. lurkers. You said:
> > In part, they use the same bandwidth that any participant uses with
> > respect to OpenContinue packets. On larger, more populated reflectors
> > this has a more severe effect on modem users than the limitation of
> > bandwidth of the reflector. I've seen modem users timeout of a
> > Cornell reflector with only 25-28 participants on the reflector. The
> > reflector itself had 45Mbps bandwidth available and was only using=20
> > 1.8Mbps of it.
> And what does this mean, if we can=B4t change it ? What can the next
> generation of CU refs change ? If I understand You, the CU clients can=B4=
t
> be modified to improve the situation at all !

It's really a moot point at the moment since the clients can't handle more
than 23/24 participants very well due to limitations of the participants
list. It just means you subdivide the reflector into more conferences.
White Pine has introduced things like "observer" and "observer-broadcast"
to deal with the scaling problems. It allows someone to show to everyone
and prevent interaction between the other participants.
The CU clients just need to be able to support more participants in the
participants list...Underlying all of this is the overhead in OpenContinue
packets..the Cornell reflector isn't designed for modem participants. The
White Pine reflectors strip a lot of the OC packets before sending to the
client...I've heard Brian Godette's Enhanced Reflector strips the OC
packets even more. I'm not sure... Maybe Brian can elaborate on this..I'm
no expert :)

> Thanks for mentioning the TRACERT utility. But.. I am surfing at calm
> times.. and there are no refs in Germany at all (besides HEAVEN),
> especially there are no refs at german universities !

Maybe you can convince some German universities to try and run one :)
Or maybe White Pine can explore that market.
Other reflectors I have listed in Germany:
194.121.224.3 Defcon-SNAFU Germany
141.39.248.18 FH-Cafe-Munich Germany
134.34.1.140 gblf.de Germany
194.94.211.200 Heaven Germany
141.46.8.60 HTWS Zittau Germany
141.44.142.11 Magdeburg Experimental Ref Germany
but only Heaven, FH-Cafe, and HTWS have been up recently.

--
streak@ccwf.cc.utexas.edu    * Jason Williams -- Austin, Tx.  |     |
streak@mail.utexas.edu       * University of Texas at Austin  | ___ |
streak@cs.utexas.edu         * BS Computer Science             \_|_/
*************** http://ccwf.cc.utexas.edu/~streak/ **************|