Time To Get To Thinking

[David Farber <farber () central cis upenn edu>]

Time To Get To Thinking


Professor David Farber
The Alfred Fitler Moore Professor of Telecommunication Systems
University of Pennsylvania
200 S. 33 rd Street
Philadelphia PA 19104-6389
farber () cis upenn edu


Prepared for ERCIM News of the Swedish KTH


Over the past four years, the United States has undertaken a joint
industrial, university, and governmental research initiative designed to
study the impact of gigabit networking on the future of networking,
networking applications, and computer architecture.  This study has led to
the formation of five testbeds, each exploring different aspects of the
emerging technology as well as motivating several non US experiments The
experiment is now drawing to a close, at least in its first phase, so it is
reasonable to ask what we've learned and what the implications are for the
future.


First, and maybe foremost, we have shown that industry and academia can
work together for their mutual benefit.  In the case of the US. testbeds,
the largest percentage of the resources and manpower were contributed to
the effort by industry without government support or extraordinary tax
incentives.  Universities, while supported by the government, found
themselves as partners in pushing the frontiers of research.  Students and
engineers worked hand in hand in each others laboratories.  This model of
collaborative research, which was so effective here, should be applicable
to other frontier activities.


But what did we learn from the research activities themselves?  Gigabit
speeds have raised a whole new set of very difficult technical issues.
Designing and building switching devices and interface devices which can
operate at these speeds is not simple.  It pushes both hardware design and
VLSI technology to their limits.  As a result, it has been necessary to
take innovative architectural approaches to even hope to achieve speeds
nearing a gigabit.


Perhaps most interesting, though, is the conclusion that many of the ideas
developed over the past twenty years in computer architecture, operating
system design, and networking protocols seem to be ineffectual when applied
to such high speeds.  It is worth observing that these communication speeds
are of the same order of magnitude as the main memory bus speeds of modern
workstations.  Thus it is not surprising that we have run into problems.
When streams of data arrive at memory speeds, it becomes difficult, given
the protocol systems currently in use, to get the data into memory, to
allow the processor enough processing bandwidth to examine the data and
move it, and still to have processing power left over for other tasks.  I
will not elaborate in this piece on the solution I and others have proposed
for this problem.  But basically, the solution revolves around the creation
of a geographically dispersed distributed machine, the components of which
would be interconnected by high-speed networks.  This approach has been
well documented.


What is more important than a particular solution is the challenge of
facing a future in which gigabit speed networking will be considered slow,
in which our communication infrastructure will consist of multi-gigabit,
low error, high-latency networks, in which our processing units, while
growing faster, will not keep up with increasing communication speeds.  It
is too easy to just remove a few instructions, hack a few cures, and show
that one can operate not too badly at current speeds of communication.
Perhaps this is equivalent to saying, "let the next generation solve the
problem."  I believe that there is a challenge facing the computer
communication field of at least the same magnitude as the challenge the
field faced in the very early days of networking.  Attacking this problem
will require the talents of people from every area of both the computer and
communications fields--people willing to experiment and willing to face the
same set of challenges those in the fifties faced with the then-new
computers.


In 1996, we will be celebrating the fiftieth anniversary of the Eniac
computer, developed at the University of Pennsylvania.  The children of the
Eniac have transformed our society in many ways, both for better and for
worse.  As we turn to the next fifty years, we are facing an era in which
the convergence of computers and communications will be the key
technological innovation.  The impact of this development on our technology
and our society will most likely be considerably greater than that of the
previous fifty years of evolution.  It is time to start thinking and
working and innovating, so that in 2046 we can look back at these fifty
years as a time of insight and advance even greater than that of the last
fifty.