[ih] [addendum, lost email of Jack Haverty, for the record] Re: Baran and arbitrary reliability from arbitrarily unreliable components
mbaer at cs.tu-berlin.de
Tue Feb 16 14:31:44 PST 2010
I have just realized that a previous email from Jack Haverty in a March
2009 thread on this list did not actually make it to the list, but only
to me -- god knows why. here it is, for the record:
Date: Thursday, March 19, 2009 9:08:26 PM
Subject: Re: [ih] Baran and arbitrary reliability from arbitrarily unreliable
Hmmm. I tried to send this yesterday, but since it hasn't come back to me yet
it must have been drawn into one of those Internet black holes. Apologies if
you get it twice.... /Jack
Greetings everyone. Good to hear voices from the past, and it's a great
discussion -- made me feel guilty enough to sit down and type in my 2
cents..maybe making amends just a little bit for all those papers that never got
written back in the 70s/80s. If you're not interested, just hit delete now....
Matthias' original question concerned whether and to what extent prior academic
work influenced the Internet. That got me thinking about the question more
generally - namely what *did* influence the zillions of decisions made by people
building the Internet. I've always been accused of being a "big picture" kind
I agree wholeheartedly with the previous comments about the difficulty of
determining whether or not someone's work or publication influenced someone
else. Even if you could somehow prove that someone subscribed to a journal, or
actually read a paper, or even understood it, he or she may not have agreed with
it - and simply ignored it as noise. I'm equally suspect of anyone who claims
to have invented any particular mechanism or approach. It's simply too hard,
in my experience at least, to be sure that an idea that pops into your head is
original, and not a product of your subconscious working on something you saw,
or heard, or read, days or months before.
Still, it's interesting to try to deduce where things have come from, especially
things as pervasive, influential, and surprising as "The Internet". So here goes...
I think the first issue to nail down is exactly what you mean by "The
Internet". In my experience, it means different things to different people,
depending on facts like how and when you first encountered "it", what you were
doing at the time, and how long it took you to recognize it as something new and
important to you. For some people, the Internet is email. Others equate it
with the Web. To some it began with the Arpanet, which was "Release 1". Or it
may have begin with CSNET and/or NSFNET, which enabled a lot of people to
"connect" for the first time. Did any particular piece of prior work influence
those efforts? I think you'd have to ask the people involved in building them.
So, although it's difficult to determine what influenced someone's decisions,
it's perhaps more reasonable to ask what influenced your own decisions. It's
not so easy to answer that question, but at least you're asking an "eye
witness". So, since I was involved in various aspects of what many people might
call "The Internet" for much of the late 70s and 80s, I've been asking myself
that question. What influenced me?
First, the definition, or better put, my own definition -- The Internet. I
think I personally focus on the "Inter" part of "Internet". There have been
many networks over the years. In the 70s/80s, there were a variety of computer
networks. Mujltidrop lines and terminal networks had been around for a while; I
remember using one around the late 60s, which connected MIT to Xerox. IBM had
SNA. ARPA had ARPANet. Other technologies were being created to form networks
of computers, e.g., the "Packet Radio" networks for tactical military use.
Commercial X.25 networks were seeking customers for the telephone companies of
the world. Tymnet, Compuserve, and others were connecting users to applications.
All of those networks used a variety of technologies, but had some common
characteristics: each was composed of uniform components (no SNA nodes in the
ARPANet, for example); each was owned and operated by a single owner; and except
for very special ad-hoc linkages, each was isolated from the others.
Where the ARPANet focused on connecting dissimilar computers, my personal
definition of the Internet focuses on "Inter"connection of dissimilar "net"works.
In particular, ARPA had this problem of building different kinds of networks,
with a need for computers on one network to talk to ones on the other. As far
as I remember, at least in the late 70s (when I first encountered "The
Internet") there wasn't any project specifically to "build the Internet".
Instead, there were a variety of projects to build different kinds of networks,
and applications that would run over those networks, and every project had the
requirement to interconnect with the others to make those applications
possible. There were a variety of scenarios that had to work. E.G., someone in
a helicopter, obviously on a radio-based network, interacting with someone on
another continent at headquarters, obviously not on the same radio network. The
aggregate of those projects' teams were the de facto Internet team - which in
fact started as two separate teams: the "TCP" and the "IP" working groups, but
was pretty quickly merged.
The obvious determinant of "dissimilar" networks was that they used different
technologies. ARPANet, SATNET, PRNet, etc. all had their own unique hardware,
software, algorithms, and architectures. I think at first that's how we
thought of the problem. TCP/IP was the "glue" that allowed communication to be
accomplished through a series of dissimilar steps.
But there was another, and I believe in retrospect even more important, nature
of being "dissimilar", namely organizational. In the 70s, I think networks were
pretty consistently homogeneously managed. I'm sure someone will correct me if
that's wrong... But as I remember, networks were owned by someone, either a
government agency, or a company, or a utility like a PTT. It was also likely
that all of the components were the same, or at least from the same vendor.
Even the ARPANet, which interconnected dissimilar computers, was built and
operated by one company. Someone was in charge - not zero, not two or more;
some ONE. That was simply the state of the art at the time.
In retrospect from 2009, the Internet is a bonanza of heterogeneity. No one
owns it, and it's not clear why it works or whose hand is on the wheel.
Virtually anyone can buy some hardware and become an ISP, hooking yet more
things into "The Internet".
Since that aspect of organizational dissimilarity wasn't prominent in the very
early days of interconnecting ARPANet with PRNet, I started wondering how did we
get from there to here. As was pointed out previously, CSNET and NSFNET
arguably led the way in making the Internet organizationally heterogeneous. But
what made it possible for CSNET and NSFNET to do that...?
If I remember correctly, at the time the ARPANet had been very successful, and
had become more of an operational communications utility than a research
project. Lots of organizations and universities wanted to connect, but couldn't
because either it was very expensive (IMPs, IMP ports and circuits cost $$s), or
because they weren't ARPA contractors and the ARPANet was restricted to support
ARPA business. There was a pent-up demand to "get on the net".
Going back to my earlier comment above, I've been thinking about what influenced
me personally at that time in the work I was doing. I was at BBN, managing a
bunch of projects which were arguably part of "the Internet", for DARPA as well
as other government agencies, all involved with either building parts of "the
Internet", or deploying clones of it into other organizations (Yes, there are
"Internets"). One of the DARPA projects was the building and operating of the
"core gateways", which were the ones which interconnected various long-haul
networks among others. So I think it's reasonable to consider whatever was
influencing me in working on those projects was influencing "the Internet" too.
At the time, there was a lot of pressure to deploy a functional Internet - one
which could support successful demonstrations of the kinds of mostly
government-oriented applications that would cause the "operational" government
gang to keep the research funding going and the funds going to ARPA (and then to
us and others). That focus, coupled with the fact that BBN was not a
university, led to a noticeable bias toward engineering rather than science.
Getting it to work, using proven techniques rather than academic ideas, became
the primary goal. Writing papers, presenting at conferences, trying new
interesting approaches, and other such science-oriented activities got pushed to
the back burner. As I remember also, all through that period most of the
interesting discussion and argument happened on the various mailing lists, or at
the quarterly Internet meetings, rather than in the traditional journals -- at
least from my personal perspective at the time. Sadly, I suspect all of that
has been lost.
The focus on engineering and using proven techniques to get things to work led
naturally to what I think was the primary influence on the Internet -- the
ARPANet, which was arguably "working" well, and more specifically the *internal*
unpublicized mechanisms of the ARPANet which had evolved over a decade of its
operating experience. Although there was considerable material in publication
about the more mathematical aspects of the ARPANet, especially the routing
algorithms, there was a rich soup of engineering "best practices" embedded in
the IMP code, the NOC tools, policies, and procedures, and the management
approaches. If I remember correctly, there were something like a thousand
separate parameters in the code that could be "tweaked" to deal with different
situations that had come up over time. As far as I know, little if any of this
was ever documented in any detail in any public way. It was pretty boring after
all. Some of it was simply to be experienced - standing as a fly on the wall of
the NOC during some network crisis was very educational.
The "Internet guys" resided at BBN literally just around the corner from the
"ARPANet group". This was purposeful, and I fought several battles over the
years within the BBN management to keep it that way. As a result, a lot of the
internal decisions associated with the "core gateways" were to steal, adapt, and
integrate ARPANet mechanisms and philosophies into the nascent Internet. This
wasn't really intentional, it just happened because of the proximity -
"technology transfer" at its best.
That ARPANet influence would naturally have evolved the core gateways and "the
Internet" into a homogeneous network like the ARPANet. All gateways would be
built by BBN, all software running the same release (and obviously the same
algorithms etc.), all operated by the same single centralized entity.
Speaking of "inventing" things, I might feel inclined to claim responsibility,
or blame, for causing a mutation of the Internet. Originally, the idea was that
the Internet interconnected networks, and the boxes that accomplished that were
called "gateways". I pushed the notion that a wire, i.e., a leased line or
virtual circuit, was simply a very degenerate type of network, which could
connect to only two "hosts" -- "this end" and "that end". So, if you put a
wire from a port on one gateway to a port on another, and treated it as just a
very simple "network", the overall Internet would still work just fine. I must
have given the slideshow presentation about this concept at least a hundred
times. Of course it meant that you would no longer need those ARPANet IMPs to
plug your gateway into. You could just unplug the long-haul leased line from
the IMP port, plug it into the gateway port instead, and the Internet would
simply take over the task of routing traffic across that line. We actually did
exactly that, to make sure it worked. At that point the boxes we called
"gateways" became "routers" and took on the role of switching. I don't think
the BBN management ever understood the implications of that concept on future
sales of packet switches, despite my slideshow efforts. Of course, at the time,
the "conventional wisdom" was that the Internet was just a research project, and
the "real" system was going to come from the PTTs, CCITT, ISO, and other
professionals, with X.25 and X.75 playing the lead role to upstage TCP and IP.
Anyway, that environment would have led to an Internet that looked a lot like
the ARPANet, probably ending up as a homogeneous network of routers
interconnecting mostly Ethernets, thanks to Bob Metcalfe. There was a lot of
momentum along that trajectory. But Bob Kahn stepped in the way....
This is one case where I remember quite clearly how the Internet was
"influenced" to change directions radically. Again, all of this is from my
personal perspective, with my personal definition of "the Internet". Others
undoubtedly had different experiences.
I was at one of innumerable meetings. Sorry, I can't remember where or when.
It was probably in DC, where I spent a lot of time, but my gut feeling tells me
it was the European Internet meeting, maybe in Munich. Anyway,... Bob and I
were hanging on the same subway strap, with the usual group of a dozen or two
people heading out to find dinner. Bob wanted to talk about the Internet
architecture, and in particular the core gateways. He managed over the
squealing of the car's wheels to overcome my skepticism and make it clear that
it would be a good idea to figure out how to make it possible for gateways not
built by BBN to be full participants in the system of gateways. I don't know
whether this was motivated by political pressures to enable CSNET/NSFNET, or
some technical considerations, or by the ARPA charter to focus on new technology
and new ideas, rather than replicating the old ones. But he convinced me, and I
went away with a new direction, and a harder task to make something work using
an unproven approach.
Back at BBN, the challenge was not only to figure out how to make a stable
heterogeneous Internet, but also how to convince the people on the project that
it was a good idea to let other people build gateways and hook them up to "our"
system. Fortunately the meetings of the TCP and IP working groups were great
training for this kind of work. I recruited one of the best thinkers from the
ARPANet crowd - Dr. Eric Rosen. He and I sat down for several multi-hour
brainstorming sessions, and came up with the notion of "autonomous systems",
which were sets of routers owned/managed by a single organization, and
interconnected with other such systems to form the overall Internet. EGP (which
I think evolved into BGP) and the concept of IGP (which basically means whatever
mechanisms are used among the routers inside their own closed system) made it
possible to use different approaches within different ASes. This led to RFC
827 and a bunch of others in the early 80s.
To me, this is what diverted the Internet from homogeneous to heterogeneous in
nature and enable the "Inter"connection of different organizations -- even if
they used the same network products, they retained control over their own
assets. In retrospect, given the experiences I later had in various commercial
"user" situations, this characteristic was crucial to making the Internet
reliable and successful.
Of course, this wasn't a new idea. Mainframes and timesharing were succumbing
to the onslaught of PCs - which allowed you to own and control your own
computing resources, rather than being at the mercy of the clowns in the "Data
Center". People like to control what's important to them.
Bob Kahn had it just right. Maybe that subway strap should be bronzed and put
in the Smithsonian. Of course, adding in all of Vint's "subway straps" would
require another wing.
These have been just a few examples, of the influences I felt while doing what I
was doing to help build what I think of as the Internet. Whew, that should be
Getting back to Matthias' original question... I'd have to say that Pouzin's or
Baran's ideas and papers, or anyone else's papers for that matter, didn't have
much direct influence on the Internet mechanisms that I was associated with.
The culture wasn't very scientific/academic oriented; magazines like Data
Communications were popular, and maybe some IEEE journals, but they were
peripheral. The science didn't apply very readily to the Internet environment
where nice well-understood, easily modelled wires were replaced by a gaggle of
networks with unknown, unpredictable, and variable behavior. So, the design
and implementation decisions were made by the practical needs of trying to make
something that worked, even if we couldn't explain why. It was very much an
experimental, engineering kind of world - watch what's happening, try something
that seems likely to help, repeat until done; this was largely what had been
going on in the ARPANet for a while at that point to refine the basic mechanisms
of packet switching. The ARPANet was probably the biggest influence on the
Internet at that time (again, from my personal perspective). To the extent
that the ARPANet mechanisms were influenced by earlier academic work, that
influence may have flowed forward to the Internet. You'd have to ask the
I think it's also true that a big influence on decisions is simply the personal
experience of the people involved. In my youth I had a model train set, and
learned something about how railroads worked. If you think of the movement of a
commodity like coal, or wheat, or logs, there's lots of analogies to "packet
switching". Logs or lumps of coal are like bits, cars ("wagons" in Europe) are
like packets, freight yards are like routers. In the late nineteenth and early
twentieth centuries, railroads built by different companies used different sizes
of track, so that cargo had to be moved from one car to another at their
junctions - not unlike what a "gateway" had to do? Railroads encountered all
sorts of problems, many with blatant relationships to our Internet world
(congestion control comes to mind), and they developed elaborate technologies to
deal with it, such as a series of signalling systems and "routing protocols" -
all well before Eniac (or pick your favorite "first computer").
With personal experiences like that, what you know from those "technology
architectures" can easily influence decisions made in a new situation. In the
Internet meetings in the early 80s, concepts like "expressway routing" were
discussed at length, and people pretty much knew the issues from their human
experiences with the highway systems. Their experiences must have influenced
their Internet work too, probably more than just adopting highway terminology.
So, if the notion of "packet switching" has a long history, how do you tell
whether you're influenced by a recent example, or one from centuries ago. Roman
generals used to dispatch several runners with copies of a message to assure
that their reports got back to Rome. They used to split messages up and send
pieces by different messengers, over different routes, to avoid interception by
the enemy. I don't think they called it "fragmentation and reassembly" but
it's the same idea. I knew this history from high school -- did it influence me
in my later work on the Internet? Did it influence Pouzin and others?
Enough philosophy, and enough words. If you've gotten this far, thanks for
listening, and I hope I've helped answer the original question at least a little
To me, the history of the Internet is the aggregate of all of these kinds of
anecdotes by all the people involved in whatever they individually think of as
"the Internet". Unlike other huge projects, like putting a man on the moon,
there was no "Internet project", and no crisp milestones -- like when it
started, or when it was completed. Are we done yet? There weren't a whole crew
of journalists documenting it along the way, since it was supposed to be
ephemeral and wasn't considered important enough to warrant the attention. But
it's a fascinating story.
Just for completeness, my personal view of the Internet was driven by my
involvement, so here's a brief summary for the record. In the mid 70s, I was a
user of the ARPANet, building various applications that ran over the net - in
particular email. From 1978 through to 1990 I was at BBN, doing a variety of
things over time, almost all somehow associated with the Internet. I started by
building TCP for Unix, ended up managing a gaggle of research projects, and
later created a "system engineering" organization to help real users (government
and early commercial adopters) deploy and use their own Internets. In 1990 I
went west to Oracle as "Internet Architect", which among other things involved
getting the corporate internet up and running, getting products to be
Internet-capable, and helping Oracle's customers (which is just about everybody)
understand the new-fangled Internet stuff and get it to work, since none of the
Internet industry's products seemed to come with a "How to Run and Manage an
Internet" or a "How to Use Your New Internet for Fun and Especially Profit"
pamphlet. So, my personal perspective on "the Internet" is an amalgam of all
The Internet is like the elephant in those proverbial stories about the elephant
and the blind man. What you think it is depends on your perspective as you
A few years ago, some organization (Smithsonian I believe) ran a project to
capture as much as possible of the experiences of World War II veterans, in
order to document the "inside" of the war experience while the opportunity still
existed. Perhaps, in its role as organizer of the world's information (which
continually amazes me), Google might take on such a project for the
Internet...? Vint, did you make it this far through my rambling......?
Point Arena, CA
- where we still don't have cell service, and the phones only do 24kb/sec, but
fortunately there are satellites.....and I'm not on the hot seat at the
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