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XX-C381B-39

February 1982

9 pages

Original

0.4MB

Document:	Why Digital is Committed to Ethernet for the Fifth Generation
Order Number:	XX-C381B-39
Revision:	0
Pages:	9
Original Filename:	Ethernet_announcement_820210c.pdf

OCR Text

WHY DIGITAL IS COMMITTED
TO ETHERNET
FOR THE FIFTH GENERATION

A summary of remarks made by Gordon Bell, Vice PresidentEngineering, Digital Equipment Corporation, at the
Xerox/Intel/Digital Seminar.

New York, February lo,1982

WHY DIGITAL IS COMMITTED
TO ETHERNET
FOR THE FIFTH GENERATION
ABSTRACT
What the Digital Unibus did for minicomputers, Ethernet will do for the Fifth
Generation.
Nearly all recent computers are organized around a single, high speed bus (Unibus-type
structure) which provides communications among its processors, memory, disks, and interfaces to the external environment. This simple structure has been one factor in the rapid
evolution and proliferation of computers. Unfortunately, a bus for interconnecting computer
components within a cabinet, is not suitable for interconnecting a network of computers
within a building.
Ethernet is a high speed, 10 megabits per second, standard bus providing the first two
levels of the IS0 Open Systems Architecture. It permits the dynamic connection of computers at a site to form a local-area network (LAN) in an open-endedfashion without the
need of centralized equipment or planning and control In the Fifth Generation, the network
becomes the system and Ethernet is a key prerequisite of the generation
Ethernet, will be used initially in an evolutionary fashion, to int,erconnect net,works of
today’s computers to each other and to terminals and personal computers. Since Ethernet
is a factor of 1000 higher speed standard than today’s network links, and easily used to
form networks, we expect a rapid transition to a tightly integrated network, where the network is the system. In this generation, separate function computers (ey personal workstation, file server,print server, real time, timeshared) will be tightly integrated, interchang
ing many types of messages, such as, files, computed graphics, pictures, and voice. This
kind of network will permit a radically different use of computers, and only then can we be
certain that this is the Fifth Computer Generation
Because Ethernet is so important to the Fifth Generation, Digital is committed to it
as a standard We use these networks and will be providing products in the near future.

Ethernet
Is The Unibus
Of The Fifth Generation

“You have to look at
Ethernet as a standard. . .”

Ethernet is one of the keys to the development of
the Fifth Generation because it provides a standard for
the interconnection of all sizes and types of computers
in a passive, local-area network.
Up until now, interconnection has been a very
difficult task simply because there has been no standard.
A standard is a blueprint that shows you how to
build the components that will go into a system or onto
a network.

system components are
connected by a single highspeed bus in an open-ended
fashion.”
“

. . .

Unibus*-type
interconnection
for Computers

15m

“Think of Ethernet as an
extended bus.. I’

Ethernet Interconnection
Forms
The Basis Of Local Area
Networked
Computing

(~~

21Lrn

If you look at current computer architecture you
will find standards. One such standard is the Digital
Unibus that defines the architecture used in the largest
selling series of minicomputers ever built-the PDP-11
series. The Unibus standard made it possible for our
users and a number of different manufacturers to build
memory boards, communications interfaces, and other
components that can be plugged directly in a PDP-11
system in an open-endedfashion.
If you look at the Unibus-type architecture, or any
competitive implementations of the Unihus idea such as
Intel’s Multihus or Motorola’s Versahus,you will find that
all system components-processor, system memory,
data storage, and data communications interfaces-are
connected by a single, high-speed data path or bus.
This bus enablesthe computer to move data
within the system at very high speeds.Unfortunately
there has been no standard bus to move data between
systems at the similar speeds.Ethernet communications
won’t replace Unihus or any competitive busses hut
Ethernet will solve the local-area networking problem.

Ethernet is an extended bus. Up until now busses
have provided high-speed computer communications
within a very limited area-a single cabinet or room.
Ethernet provides an extended bus that will link information processing nodes throughout a building, campus,
or industrial complex
The system components don’t change. You have the
same components in an Ethernet as you have in a single
system. The only difference is that you now have more
components and they’re dispersed over a wider area.
Where a IJnihus system has a single processor, an
Ethernet can have many
Where a Unibus system has local data storage, an
Ethernet, will support databases distributed throughout
the network.
Where a Unibus system interfaces to other computers, an Ethernet interfaces to other networks through
gateways.

.
.

‘
.

“The network becomes the
system. . . I’

In other words, with Ethernet, the network
becomes the system. And when this happens,we will
have a whole new computer generation-The Fifth
Generation.
We-that is Digital Equipment Corporation-want
to be a leader in the development of this new generation
just as we were the leader in interactive computing and
the development of the minicomputer generation that
made distributed data processing possible.
Let me take a minute to define what I mean by
a computer generation.
A new generation of computers comes about when
there is a convergence of Technology and Need that
forms a new Structure that is then followed by general
Use.
With Ethernet and VLSI-Very Large Scale Integrated Circuits-we have the technology. That technology is needed to build and network an ever-growing
number of computers, terminals, intelligent workstations,
and personal computers that are being bought to solve
many of the productivity problems facing businesstoday.
There is also a new structure, the local-area network. Just as minicomputers and distributed processing
changed the way computers were used in the 7Os,localarea networks and personal workstations will change
the way computers are used in the 80s.
The final requirement for a new computer generation is customer acceptance. Will the new technology
and the new structure come into general use? In this
particular case, I am convinced it will. Just as I’m convinced that Ethernet is the technology that will make
this happen
Ethernet provides the simplicity, speed, and universality needed in local-area networking.
Unlike other local-area networks, Ethernet is openended. It allows the user to build a local-area network
from the bottom up without making a large capital investment or developing an inflexible long-range plan
As I mentioned earlier, Ethernet is a passive communications medium. An Ethernet is really nothing more
than a coaxial cable and standard protocols that define
the way dat,a is transmitted. For example, the Ethernet
protocol defines packet size. It defines the way packets
are addressed.It’s really very simple. And its been tested
for 10 years and it works.

Ethernet can carry a great deal of information at
very high speeds.But you don’t have to take my word
for it. I’d like to read you part of an advertisement
written by another computer manufacturer who adopted
the Ethernet standard.
“Instead of taking. . . 44 seconds to transmit 10
pages of data, the transfer takes place in .042 second.
In the 4.4 seconds it would take a conventional network
to send one page of War and Peace.. . you could send
the entire thousand page novel.”
It is not difficult to see the benefits. You can tmnsmit entire files from a computer to a personal workstation almost instantaneously. You can transmit
photographs, data sheets, engineering drawings, or even
voice messages.
The key is universality Any manufacturer who
follows the Ethernet, standard can build equipment to
go onto the network.
But it is important that we realize that a network
is more than just lines and nodes.Higher level protocols
are needed to support the interconnection of dissimilar
computers; to implement complex network functions
such as tile transfers and terminal-to-terminal communications; and to provide network management
capabilities.

“Higher-level
needed.. f

protocols are

These protocols are complex. But they are a prerequisite for building a network such as the one that
serves Central Engineering at DigitaL One of the reasons we are committed to Ethernet is that it fits into
the framework defined by Digital Network Architecture.
We don’t have to change the higher level protocols that
are being used to support tens of thousands of DECnet
nodes around the world. We can make Ethernet part
of DECnrt. We have a fit. And we have the range of
capabilities required to implement complex computer
networks.
Let’s look at an example.
Digital’s Engineering Network is made up of over
200 different systems serving about eight thousand
terminal users. But interestingly enough, 80% of the
traffic on this network is local traffic-only 20% of the
traffic is hetween locations.
Local-area networking addresses the local problem.
It provides high speed interconnection among computers within the same building or complex, and it simplifies the interconnection of terminals and processors
to host computers.

“Ethernet can eliminate
this complexity while
providing the flexibility
needed for future growth’

Let’s look at the computer-to-computer and
terminal-to-computer interconnection problem in a little
detail
The problem is a wiring prohlem. It is one thing to
connect A to B; quite another thing to connect A to B
through Z. Before you know it you have a very complex
maze of wires and switches. This is the wireroom in our
Spitbrook, New Hampshire facility. As you can see,
interconnecting a large number of devices is-at besta very messy and, I might add, very expensive, business.
You have fixed wires running all over the place. It’s
difficult to add systems or make changes.
Ethernet can eliminate this mess and provide
needed flexibility Ethernet will let us replace all this
wiring with a single coaxial cable that will run throughout the building. When we want t,o add a terminal we’ll
just tap into the cable. It won’t be necessary to run
wires hack to a central location. And we’ll he able to add
terminals t,o the network without interrupting network
operations.
But we-like most other large organizations-are
starting to provide individual users with intelligent
workstations or personal comput,ers rather than simple
terminals. A simple t~erminalis usually a low speed
device that, can operate over telephone-type wiring.
After alI I can only read and writ,e just so fast. I can type
50 words a minute. I can read about 200 words a minute.
9.600 hit per second transmission is more than fast
enough for me as long as I only have a simple terminal.
But when I have an intelligent, terminal that tan deal
with information a lot faster than I can, I need to be able
to communicate at computer speeds.Ethernet provides
the speed needed to support intelligent user devices.
The speed neededt,o transfer entire files or complex
graphic images in a hxtion of a second.I needEthernet
communications.

“This is how our computers
are connected today”

“Ethernet eliminates
message switchingJ

At the same time Ethernet solves the problem of
interconnecting computer systems.
This is how the comouters at Digital’s Spitbrook.
New Hampshire facility are connected today-As you
can see messages have to bc routed through the network. This creates computer over-he&d.Many systems
spend much of their time switching and forwarding
messages.And as more and more systems are added to
the network this overheadjust keeps growing and
growing.
Fortunately, Ethernet can eliminate the overhead
problem because it eliminates message switching and
forwarding. This is how Spitbrook will look when we
install an Ethernet.
As you see each system is connected directly to
the Ethernet. There is no message switching. No
routing. No forwarding. No computer overhead.
Instead of a maze of wires you have a high-speed,
high-capacity extended bus that serves the entire complex. As you see Ethernet is changing the vep definition of a system. With Ethernet, the network becomes
the system.
We have a new technology. A pressing user need.
And, a new structure. Three of the four prerequisites
for a new computer generation. The fourth requirement
is use. There are currently about 100 Ethernet,s in
operation There are going to be thousands. We’ve
already talked to our customers. We know what they
want and we know that many of them are going to
install Ether-nets.That,‘s why I believe that we’re looking
at a new computer generation.

“Within the next few months
we will be introducing our
first Ethernet products.”

We’re going to build that generation. That’s why
we joined with Xerox and Intel to develop the Ethernet
Specification. That specification conforms to both The
Open Systems Architecture proposed by the International Standards Organization and Digital Network
Architecture used in thousands of networks around the
world. Right now we are implementing Ethernet as a
part of Digital Network Architecture and within the
next few months we will be announcing our Ethernet
program and introducing our first Ethernet products.
I believe that Ethernet is one of the keys to the
development of the Fifth Generation just as the Digital
Unibus was one of the keys to the development of the
minicomputer generation.