Re: Could someone resolve some debates/questions for me please.

Jason Williams (streak@ccwf.cc.utexas.edu)
Fri, 13 Mar 1998 01:03:26 -0600 (CST)


On Thu, 12 Mar 1998, J. Stephen Downie wrote:
> Debate #1: Having a high rec max rate (say 150) on a cu client actually slows
> down the ref. True,false, somewhere in between?

somewhere in between...It doesn't matter what rates the clients have if
the reflector has enough bandwidth to support it. The typical reflector
is on at least a T1 so the bandwidth for one participant doesn't amount to
much. The only problem is when you get lots of OTHER people on T1s
running a max send of 100 and max receive of 500. The bandwidth can vanish
quite quickly that way.
For your typical modem user with a max receive rate of 150, nothing
happens except they are potentially flooded off of the reflector since
they can't support that rate. Ideally, the reflector should cut back the
receive cap if it notices lots of packet loss so eventually they won't be
flooded. Whether this happens or not, I don't know. I do know that too
high of max send and/or receive rates on modems is the main cause of lost
chat.

If the person who sets their max receive to 150 actually HAS the bandwidth
for it and they have enough vids open to actually receive 150kbps of data,
then it does eat up more bandwidth on the reflector. It will only slow
the reflector if the reflector has very limited bandwidth to begin with
(or its pipe is already full).

If the person who sets their max receive to 150 DOESN'T have the
bandwidth, it only potentially floods them. They can only receive
typically 28 or 33kbps so eventually they'll either get knocked off if
they have enough vids open to warrant 150kbps or the reflector will notice
they are dropping packets and cut their cap down. At least that's how I
understand it.

>From talking with Brian about something like this, his Enhanced Reflector
doesn't boot participants off for incorrect receive settings because the
reflector just limits how much it sends to each client.

> Debate #2: Setting mins to 1 on a client always boosts performance.
> Which begs the question, Why not just make 1 the default mins? True,
> False, somewhere in > between?

False...Setting mins to 1 on a client DOESN'T boost performance at all.
The only time I've seen lowering the mins help was when I was on a
14.4kbps connection a few years back and trying to see someone on sending
at 28kbps. I couldn't see them well unless they lowered their max-send to
5 and my min-receive was at 5.

The mins don't really do anything at all from what I can tell..The
reflector isn't going to send vid data that isn't there.
It doesn't hurt to set the min to 1, but it certainly doesn't help much.
The only point I see for reflector operators to mess with the min rates is
to piss people off. It doesn't save them any bandwidth. All it does is
force people to reconnect if they have the wrong rates.

On the OTHER side of it, when I've conferenced on the campus' T3, it did
come in handy to be able to set the min SEND up to 30 or 40 so my rates
wouldn't drop down for modem users. But min receive didn't do anything.

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