Subject: Re: QOS Routing - high level comments (long)

From: [email-masked] (James E. [Jed] Donnelley)
Date: Thu, 4 Apr 1996 14:58:08 -0800

>I would like to solicit some responses to two questions
>with regard to QOS routing. Just to start off, I'm giving some
>possible answers.
>
>1. Is there a need for QOS routing in the internet?

I believe no.  I am sure you are familiar with George Gilder's
articles:

http://www.seas.upenn.edu/~gaj1/ggindex.html

If not, I would recommend at least the first and last (and perhaps
the second to last).

At any rate I basically buy his argument that the available bandwidth
is increasing at a sufficient rate (given that the regulatory
environment gets out of the way as it sort of seems to be
doing) that QOS in the insides of the network is not needed.
Bandwidth and performance (I expect) will soon become constrained by
the bandwidth to and in the home/office.  Even that bottleneck
will likely soon be replaced by one in the end equipment.
If that sort of environment would come to pass (is it wishful
thinking or a real direction?) then QoS inside the network
doesn't seem so necessary to me.

I base this position largely on the current availability
of OC48 equipment for deployment (generally not yet deployed),
OC192 equipment under test, and WDM equipment showing
promise in the research environment.  If the available capacity
from fiber in the ground goes in many cases from 45 Mb/s to
2.4Gb/sec and then to 10Gb/sec and then to 100Gb/sec, we are
talking about a factor of 2000 increase in available bandwidth
per fiber.  With somewhat more fiber at strategic places,
suitable caching for relatively static information, etc. I
believe our communication infrastructure can be made to
work without QoS guarantees.

I know this is a very high level argument.  I think sometimes
such high level arguments are appropriate.  I happen to think
this is one of those times.  Just an opinion.

>2. Assuming that an IP QOS routing architecture is needed, what are the
>requirements for it?

NA

>Regards,
>Bala Rajagopalan
>([email-masked])

I am guessing that a lot of the communication optimization efforts
of the past will begin to look a bit like the software optimization
efforts of the more distant past - namely somewhat overdone.  A base
level of optimization is important (e.g. compilers in the software
case, reasonable minimization of headers, compression at
appropriate places, caching, etc.) in the communication case.  However,
I expect that the careful customization of communications to squeeze
out the last 10%-20% will probably soon be seen as silly.

Note particularly the interesting "flate rate" argument
near the end of the last Gilder article.  That does seem
to fit a trend.  With more real bandwidth available to
feed it, that approach could really catch on.  QoS and
flat rate don't seem to fit together in my opinion.

This will be interesting to watch...

>This is a good point, and I guess it applies to the notion
>of IP QOS in general. But once IP QOS (along with RSVP) is
>an accepted notion, the traditional simplicity vanishes, and
>QOS routing seems to be just a missing (essential)component
>of the picture.

Why do you think it is essential?  I know this is a popular
concept, but I just don't see it.  With enough bandwidth
I don't think I need QoS.

Having said all that, I must admit that I have developed a
switching approach that assures "QoS" that I call "Just In
Time Switching" for the WDM environment.  I don't see much
future for it, however, until WDM becomes real and the
electronic bottleneck begins to be felt - 5 years?  What
do you think?

Regarding the note from  [email-masked]
(Albert E. Manfredi):

>If the basic nature of that
>traffic and those users changes radically, one would have to expect that
>the algorithms supporting that traffic and user base will no longer be
>optimal. Simple "reachability" criteria, which are all that's now
>provided, are not adequate for the general case.

As I mentioned, I believe there is a bit too much emphasis in some
quarters on optimality and not enough on gross performance and
functionality.  If we have some number of OC192 pipes coming into
a switching center, I think the main issue will be getting that
data in and out in the right direction.  It will be important
not to throw the data on the floor except when there is real
and substantial congestion, but beyond that I think the
capacity will be there to handle it.  QoS as it is currently
being configured appears to me to be more a hinderance than a help.

An opinion.  You asked.  Your question was pretty high level.

--Jed   http://www-atp.llnl.gov/atp/jed-signature.html

---

From: [email-masked] (Andrew T. Campbell)
Date: Thu, 4 Apr 1996 18:48:11 -0500 (EST)

> doesn't seem so necessary to me.

WDM or not - you will need some QoS controls inside the network.
Conjecture: as the pipe grows its very likely that 
the required QoS controls inside the network grows too.
Of course, that is for networks which choose to 
distinguish per-flow QoS.

> With enough bandwidth I don't think I need QoS.

Ditto.

-- 
Andrew
http://www.ctr.columbia.edu/~campbell
(212)-854-3109