|Implications, the First International Conference on Computer
Communication, October 24-26, 1972, Washington, D.C.
Special thanks to Yngvar Lundh, Paal Spilling, Gisle Hannemyr, Peter Kirstein, Les Earnest, Louis Pouzin, Dag Belsnes, Andrew Hinchley, Robert Kahn, Dave Mills, Vint Cerf, Horst Claussen, and Hans Vorst for providing background
or documents about this important period of Internet history. Ole Jacobsen,
Patrice Flichy and Klaus Fuchs-Kittowski also provided helpful material or suggestions on people to contact, as did several people on mailing lists. Please know the help is appreciated. And thanks to Jay Hauben and in memoriam to Michael Hauben for the work done that has set a foundation for the understanding of Internet history. Also I want to thank Dr. Samuel Moyn for his encouragement, helpful comments and discussion toward the research for this paper.
An issue of the Computer Communications Review (vol 20, no 5, Oct
1990) provides a set of ARPANET maps documenting different phases in the
development of the ARPANET. The maps are also helpful in providing a
chronology of the transition from the ARPANET to the Internet.
Following are some of the relevant dates:
Jun. '75 - Satellite circuits now cross oceans to Hawaii and the UK.
First TCP implementations tested in this configuration by Stanford,
Bolt Beranek and Newman (BBN), and University College London (UCL).
April '79 - Multiple satellite links to UK and Norway. According to
Kirstein, one UK-US link made via the commercial British Post Office
International Packet Switched Service(IPSS) using IP/X.25, the other
using the SATNET. Some UK traffic starts using the IPSS route.
Mar '82 - Norway leaves the ARPANET and become an Internet connection
via TCP/IP over SATNET.
Nov '82 - UCL leaves the ARPANET and becomes an Internet connection.
Cerf writes that in 1979 satellite systems were extended to include
the ground stations in Italy and Germany. (Cerf, "How the Internet Came
to Be") Horst Claussen confirms this:
Describing the participation of Germany in SATNET, Claussen writes:
"Having no access to some of the documents I saved back in Salzburg:
the first access to the Arpanet was established in the 1977-1978 timeframe
when I was involved in the DARPA HOL program which later on led to the
programming language Ada. We connected through a Public Data Network to the
VAN gateway at BBN and were "on the net". Later on the idea came up to
cooperate with the German Space Research Center (then DFVLR - now called
DLR) in Oberpfaffenhofen who was involved in satellite communications
and had a cooperation with Comsat Labs. Comsat Labs also was involved in
the SATNET and this way we got back to DARPA - Bob Kahn was very
supportive and so was Vint Cerf. Then I joined DFVLR in 1981 and we
found support in the German Ministry of Defense and we also could get
funding for a PSP (I recall that the thing cost us $275K - and that at a
time when the exchange rate for the German Mark fell through the bottom!)
The most difficult thing was to get the support of the German PTT - Research
Center people who "owned" and operated the old Symphonie Station at
Raisting; Symphonie was an early satellite project funded by the EEC which
had been terminated and there was this beautiful antenna and ground station
building sitting empty at Raisting. Mostly through the unofficial support by
the local engineers we were able to set up the PSP and the gateway at
Raisting and connect to the research center at Oberpfaffenhofen which is
some 20 miles away. Don't ask me how much we had to pay for the 9.6kbit/sec
leased line from Oberpfaffenhofen to Raisting - horribly expensive.
When it comes to the exact dates I will have to dig up some of my old files
but officially it must have been at least 1982, maybe even 1983 until we
got the official permission, however, we did operate the SATNET station
almost a year under a ‘temporary testing agreement’.
In May 1985 we ran a combined Packet Radio - SATNET demonstration for the
German Armed Forces and for the US Army at Heidelberg simultaneously and
this was quite successful. SATNET was in operation after I left DFVLR for
another year or two and used mainly for measurements and tests besides being
used for Internet protocol development. (I forgot to mention that we did
implement IP, TCP, UDP etc. in Modula-2 for our own VAX system and that this
implementation was later ported to the Siemens computers used by FGAN
(another government lab working for MOD) for the Packet Radio - SATNET
demonstrations.” (Horst Claussen, Email, April 17, 2003)
Hans Dodel offers a similar account:
"The German participation in SATNET began in the seventies, when the German military became interested enough to ask their ‘Consultant Agency’ IABG to watch what was going on there. Within IABG it was Dr. Horst Claussen who would come to the SATNET meetings then, which I joined in 1979 or 1980.
Horst and I both joined the German Air and Space Administration
DFVLR and spent many years there, working on SATNET and
establishing the first Gateway to SATNET in continental Europe.
(I think the Royal Signals and Radar Establishment in Malvern,
UK, beat us by a few months.)” (Hans Dodel, Email, April 17, 2003)
These accounts help to document that there were both ARPANET and Internet connections between UCL, Norway, Germany and the US.(36) The Packet Satellite Program (PSP) provides a means of understanding the transition from the ARPANET to the Internet with the development of TCP/IP. First the ARPANET was used to
develop TCP/IP. Then SATNET was created as a packet satellite network, and the research on TCP/IP was transitioned from the ARPANET to SATNET providing communication between diverse networks via TCP/IP. Hence this was an important step to creating the Internet. A series of Packet Satellite Program Working Papers (PSPWP) were issued to document "Ideas, specific investigations, and results and software and hardware specifications." (Spilling, Lundh, and Aagesen) Like the Packet Switching Protocol group that Lundh describes, the Packet Satellite Program (PSP) held regularly scheduled meetings, rotating through the institutions where the researchers worked. This was to encourage
the exchange of ideas and the coordination of their activities. Norwegian researchers explain the nature of the program. They write (Spilling, Lundh, and Aagesen):
"In mid 1975 the Packet Satellite Program (PSP) was initiated
by DARPA, with the purpose to develop a satellite-based, packet-
switching communication network, to demonstrate its capabilities,
and to investigate its performance factors."
The program involved the collaboration of a number of research groups in the US and Europe. In the appendix to the Report they list the groups.
SATNET was used as an experimental testbed for their research. To begin
with, SATNET was an integral part of the ARPANET, but as the research evolved,
SATNET became a free standing separate network. The devices connecting
SATNET with the ARPANET were called Gateways.
Describing the importance of gateways and Kahn's foresight regarding
the development of the Internet, Kirstein writes (Kirstein, Email, July 3,
"Bob Kahn's real contribution here was to recognize in 1974
the conceptual need of these gateways and to design them
at a level which would endure."
Kirstein also describes other important innovations that were crucial at
the time, but didn't endure. Yet these innovations played an important
role in helping the Internet survive a number of obstacles it faced.
Kirstein writes, (Ibid):
"One of the really important developments of the mid '70s
was the ability to create relays and gateways between
networks to allow different technologies to be interconnected --
without a complete capitulation by each group to adopt the
US and Internet Suite. Some like DECNET and BITNET capitulated
in the late '80s; others like the British networks, stayed different
until the early '90s. However, it was because they were
interconnected, and IP was then demonstrated to be better that it
really won the war....My own approach was pragmatic; it worked
well at the level, and for the purpose, that I intended; however,
it could not be extended to meet the needs of the future generation.
To give...an example of the importance of the connection capability,
I was ordered by 1977 (by people in our research council) to stop
work on IP networks, because they were contrary to the British
activities. It was only because of support from other bodies in
the UK and US, and because I could continue to work with the IP
networks connected to the favoured British flavours, that the
large-scale experimental services could continue over the next
Elaborating on how ARPANET and SATNET were different entities,
"ARPANET and SATNET operated in parallel for a long period.
UCL in London and NDRE at Kjeller had both access to
ARPANET via a TIP at UCL and a TIP at Kjeller....There
was a leased line from London to Kjeller and a fully or
partly defence-related line from Kjeller to Wiesbaden
in Germany and then over satellite to the ARPANET in the US
This was the situation as far as I can remember until say mid
1982. The SATNET experiment ran from 1976 till 1979. Then it
turned 'operational.' That meant, no real experiments.
Further it meant that European sites, mainly NDRE and UCL
could start interconnecting their local networks to SATNET
via Gateways at Kjeller and UCL, and communicate with US hosts
through a Gateway in the US This replaced gradually the
services provided by the TIPs or via the TIPs. This was then to
be known as the INTERNET, with capital letters, and as such was
a fact at the end of 1979.
Spilling notes that:
"ARPANET links from the US over satellite to Kjeller and a
narrow-bank link further on to UCL, were not efficient and required
special treatment by BBN. It was therefore a push to move away
from ARPANET and over on SATNET. NDRE had its first INTERNET
host up 1981/82, making use of Dave Mills' 'fuzzball' software."
But Spilling does not have a direct reference to when the ARPANET
link to Kjeller/London was decommissioned. Kahn confirms these accounts.
He writes (Kahn, Email, Sept. 5, 2002):
"(I)n the 1970s, I initiated a broadcast packet satellite (SATNET)
experiment on INTELSAT IV with the first participants being the US
and UK. The third participant (of what eventually were five
participants) was Norway. We were already conducting internet
experiments over SATNET in the late 1970s using TCP/IP.
In the early 1980s, we decided to rely solely on SATNET for
connectivity with Europe and thus the two 9.6 kbps lines, which were
running in parallel with the SATNET connections, were decommissioned."
As Kirstein and Kahn emphasize, there were five nations who were
participants in the SATNET experiment. He writes that SATNET included
not only the US, Norway and Great Britain, but eventually also sites
at DFVLR in Oberpfaffinghofen, Germany (near Munich), and CNUCE in
Pisa, attached to the Fucino earth station in Italy. (Kirstein, Email,
July 3, 2002)
Providing a general chronology of the development of the
3 different packet networks that TCP/IP interconnected to become
the Internet, Spilling writes, "DARPA...had three different networking
technologies under development in the '70s, namely:
o The ARPANET; 1969 ->
o The Packet Radio Network (PRNET); 1973 ->
o A packet satellite network, called SATNET; 1976-1979
"This implies," Spilling writes, "that the need for a protocol
that would connect these diverse networks was recognized early
on and that resulted in the paper by Cerf and Kahn, "A Protocol
for Packet Network Intercommunication."
Explaining the difficulty of involving different countries in
the research process, Spilling writes:
"The start of the development and experimentation with SATNET
was considerably delayed. The idea was to use one 64 kb/s
channel in the so called 'Multi-destination half duplex'
mode, with ground stations in Norway, England, Germany, Italy
and the USA. The endpoints of this channel were terminated
in equipment owned by different organizations. This was unheard
of in the Intelsat/Comsat organisations, and they had no policy
for handling this case -- no regulations and no tariff ratings.
If I remember correctly, Bob Kahn spent a long time hammering on
the satellite organizations -- more than a year -- to have them
accept this new mode of operation."
Spilling explains the result of the creation of SATNET was the
creation of the INTERNET. He writes:
"When SATNET development was ending in 1979 and the TCP/IP protocols
were matured sufficiently, SATNET was used as a means to interconnect
local area networks in Norway, England, Germany, and Italy with
ARPANET, which interconnected many LANs scattered all over the US
continent. This constellation formed the INTERNET with capital letters,
interconnecting defence institutions and research institutions with
military contracts, hence forming a very closed community. As you
have mentioned, you needed permission from DARPA in order to connect
with this community.
According to Kahn, by the 1980s there was a connection between
these different country networks using a gateway to SATNET and then
a gateway to connect to the ARPANET, "This was not a link over ARPANET,"
he emphasizes(Kahn, Email, Sept 11, 2002), "It was a connection
using SATNET, which was a broadcast satellite system.... This is
if you like an ETHERNET IN THE SKY with drops in Norway (actually routed
via Sweden) and then the UK and later Germany and Italy. (Graphic IV)
Kahn explains that NDRE and UCL had been experimenting with TCP/IP before
the cutover to TCP/IP took place on the ARPANET in January 1983. Therefore
until January 1983, NDRE and UCL had two paths they would use. They could
still use NCP over the ARPANET links until they were dismantled...and in
parallel TCP/IP could be used over SATNET. Once the ARPANET links were
dismantled, they had only the SATNET remaining." (See also From the ARPANET to the Internet: A Study of the ARPANET TCP/IP Digest.) http://www.ais.org/~ronda/new.papers/tcpdraft.txt
When the ARPANET nodes serving the UK and Norway were decommissioned,
researchers in these countries had to use TCP/IP over SATNET.
Responding to a question as to whether the 1983 cutover to TCP/IP
on the ARPANET created a new form of connection on the ARPANET,
Kahn replies, "No. It was not a new form of connection so much as it was
using a different protocol over the ARPANET (i.e. TCP/IP vs NCP) and thus,
in effect, everyone on the ARPANET was now Internet enabled since they
could talk with anyone else with TCP/IP on the Internet."
Graphic I – Diagram of NPL, CYCLADES and ARPANET as prototype for Internet
Graphic II – Diagram of UCL, NORSAR and ARPANET links from Kirstein’s 1975 paper
Graphic III – Diagram of plan for 1981 IIASA computer networking linking research centers in Eastern and Western Europe and U.S.
Graphic IV – SATNET as an Ethernet in the Sky
Graphic V – 1977 Internet Experiment
Ronda Hauben © 2004
Last updated: May 1, 2004
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