Re: Refs or no refs

Jason Williams (streak@ccwf.cc.utexas.edu)
Mon, 27 Oct 1997 00:37:16 -0600 (CST)


On Sun, 26 Oct 1997, Rolf Hemmerling wrote:
> Jason Williams wrote:
> > The reason it's a good thing is because it allows you see and be seen
> > by multiple people. This is compared to software like Freevue and
> > iVisit which allow multipoint conference without a reflector but the
> > bandwidth you send at is reduced for each person that wishes to see
> > your vid. If you are sending 20kbps and you have 5 people watching
> > you, each person only gets an average of 4kbps from you. With
> > CU-SeeMe, if you send 20kbps on a reflector, everyone can get you at
> > 20kbps regardless of how many people are watching you.
> If You don=B4t have at least a T1 connection (no private Internet client
> has such in Europe !), that=B4s the baddest thing with CU (I am connected
> by 28.8 kbps / 33.6 kbps):

Actually, that's not quite true...I believe you're taking my statement
"can receive" to mean "will receive". From what I understand, the
reflector regulates the bandwidth that gets distributed to everyone. Just
because it CAN send 20kbps to you doesn't mean it will. CU has a lot of
packet loss reporting techniques (though I'm no export on it).

> If You would like to see just a few people, selectively (because You
> know that Your bandwidth is limited), everything works fine with iVisit,
> if not too many people want to watch the same person.

The big difference though is that you can't control how many people watch
one person. If you have one person connected to 6 people their bandwidth
is distributed among those 6 regardless of if you want to only see that
one person. Increasing the scale and things get even worse. With 20
people connected to one person, each person only gets 1/20th of their
sending limit. iVisit is nice for smaller conferences but it doesn't seem
to scale up very well which is fine for modem users.

> On an occupied, busy CU-ref, You don=B4t see a single picture of a / any
> user even after 10 minutes, or so.=20

Perhaps that's just net congestion from your location. Reflectors do have
the effect of requiring all traffic to go through a certain IP. If you
have poor response from that IP, all the traffic from that reflector will
be horrible as well. That's why a lot of overseas people I've come across
tend to stay on the overseas reflectors closer to them. Ivisit directs IP
to direct IP so you can get great response on a few people at least (or
can anyway).

I've been on a reflector of 20-25 people for a few hours at a time and
never seen people halt. A lot of the problems can be attributed to 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 vids at a time.
This seems to be fixed in the 3.X versions from what I can tell.

> Especially lets discuss about the negative influence of "lurkers"
> (people without cams) on the bandwidth available for "true" users with
> cam ! From my point of view, they are bad anyhow, but with Cu refs, they
> ruine the system performance overall. It is really the bad thing for CU
> refs that lurkers ***receive*** video ?!!! Think about it !!

I don't buy this at all. Bandwidth is bandwidth...especially if you're on
a modem. Whether you send 14kbps and receive 14kbps, or send 0kbps and
receive 28kbps, it's still limited to 28kbps total bandwidth. Of course
there's still compression so you get more than 28kbps but it's still
limited bandwidth. While I agree I don't particularly care for lurkers
either simply because it's called CU-SeeMe for a reason and not just
"SeeMe". Everyone has to start somewhere since you don't start out with a
camera. I can sympathize with lurkers simply because I was one once. But
if you're in the US, the Quickcam is fairly cheap so there's no excuse to
not get a cam if you get really into CU-SeeMe.

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 1.8Mbps of it.

> There is the contradiction between the Top 10 % "busy refs" like
> "University of Vaasa" and "Ostfold/Fenris" where You may have contact to
> people (but with non-acceptable video transfer rates),and the 90 % rest
> which is really empty all the time !!!

My only suggestion is to find reflectors which are closer to you. You can
use tracert in Win95 to figure out the shortest path.
Even if the other 90% weren't empty, it wouldn't help you from what it
sounds like.

> Remember, CU is mostly used not to chat with friends but to learn new
> friends or to chat with strangers (strangers at the beginning of the
> chat, maybe friends at the end of the chat), especially because of the
> conference mode feature !

I disagree...I use CU to chat with friends and meet new people that
may/may not become friends. A lot of the private reflectors out there
exist to chat and see friends since not everyone has equal chances of
getting to private reflectors.

--
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/ **************|