Subject: Re: reading for INT SERV meetings

From: [email-masked] (Frank Kastenholz)
Date: Fri, 25 Mar 94 08:54:10 EST

> Convince the general public that IP is suitable for Integrated Services?>
 > I think you have to convince half the IETF too!

I would imagine that development and fielding of the necessary
protocols, even on an experimental basis, would present an existance
proof that IP is suitable, and therefore, be a credible and powerful
argument for the pro.

--
Frank Kastenholz
FTP Software
2 High Street
North Andover, Mass. USA 01845
(508)685-4000

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From: [email-masked] (Dave Crocker)
Date: Fri, 25 Mar 1994 07:51:23 -0800

At  3:48 PM 3/25/94 +0100, Christian Huitema wrote:
> What I mean is that for classic audio or
>video application, in a point to point or small group environment, it is
>possible to design applications that adapt dynamically to the network's
>quality of service. Much in the same way that the average TCP adapts its
>windows to the variable networking conditions.

ATM appears extremely well-suited for constant bit-rate work, along the
lines of classic telephony.  What seems to be missing from much of the ATM
discussion and work is a systems-level ability to deal with highly variable
(i.e., stochastic) behavior.  Hence, the right way to use ATM, now, is as
pure TDMA, with the very convenient ability to change the size of the FIXED
slices quickly and easily.  (An example of the difficulties for ATM is that
any tendency to deal with congestion by throwing cells away is going to
kill performance if the client protocol is fragmented to fit into cells.)

The data world, on the other hand, just LOVES stochastic behavior.  What
waits to be seen is whether we can add serious delivery timing guarantees.
(We also have to learn not to throw those packets away.)

Dave

P.S.  A small item that frequently is missed when talking about real-time
video or audio is that compression algorithms being used often produce a
VARIABLE bandwith stream.  I.e., the stuff ceases to be constant bit-rate.
I.e., the systems demand becomes variable.

Dave

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From: [email-masked] (Drew Perkins)
Date: Fri, 25 Mar 94 22:56:47 EST

> (We also have to learn not to throw those packets away.)

Dave,
	You may have not been following the work going on in the ATM Forum for
more than the last year.  ATM is being enhanced with an Available Bit-Rate (ABR)
capability to be used for data.  There are currently two schemes being
thoroughly investigated and discussed; one is rate-based and the other is
credit-based.  Once these are in place, ATM will simultaneously provide very
good support for Constant Bit-Rate (CBR) and Variable Bit-Rate (VBR) traffic like
voice and video, but will also include very good support for data traffic as
well.

Drew
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