20 YEARS - ONE STANDARD: The Story of TCP/IP

[Dave Farber <dave () farber net>]

------ Forwarded Message
From: "Jonathan B. Spira" <jspira () basex com>
Date: Wed, 1 Jan 2003 13:51:10 -0500
To: farber () cis upenn edu
Subject: 20 YEARS - ONE STANDARD: The Story of TCP/IP


Dave, Happy New Year

In recognition of TCP/IP's 20th, we prepared this short history, which may
be of interest to IP readers.

Best. 

/s/ Jonathan 

Jonathan B. Spira
CEO and Chief Analyst
Basex
E-mail: jspira () basex com
Tel: +1 (212) 725-2600 x113
www.basex.com
_______________________



01.01.03
20 YEARS - ONE STANDARD: The Story of TCP/IP
by Jonathan B. Spira


The story of TCP/IP began in 1973, when Robert Kahn, a former Bolt Beranek
Newman (BBN) employee who had joined DARPA after BBN had built and
delivered the first node of what was then considered a new
government/research network to UCLA, joined forces with Vinton Cerf, then a
graduate student at Stanford.  The experience Kahn had had with the
Interface Message Processor (IMP) and Cerf with the Network Control
Protocol (NCP) made them the perfect team to collaborate on the development
of what was to become TCP/IP.

Kahn and Cerf were acutely aware of the difficulties of making computer
communication more widespread; heterogeneous computers with differing
operating systems needed to communicate freely.  Their eventual design was
prescient, as today's Internet is a decentralized system; each node
(regardless of its function, e.g. as a Web server, a Web browser, a mail
server) is a peer and this aspect is perhaps the greatest reason for the
Internet's ubiquity today.

Cerf and Kahn, in the summer  of 1973, sent a proposal to the International
Network Working Group for a "Protocol for Packet Network
Inter-Communication."  The proposal described a new protocol that acted
like an envelope, carrying parts of a letter inside; the broken up letters
were called "datagrams."  This new protocol was called the Transmission
Control Protocol (TCP).

In 1977, BBN used TCP for the very first time on a UNIX system.  In 1978,
Cert, Jon Postel (1948-1998), then Director of the University of Southern
California's Information Sciences Institute (ISI), Computer Networks
Division, and Dany Cohen, in a meeting at ISI, decided to split TCP into
two separate protocols.  The result was TCP and the Internet Protocol (IP).
TCP retained the responsibility for brekaing up the datagrams and messages
and reassembling the packets at the destination.  IP was resonsible for
transmitting the individual datagrams across the network.  IP essentially
addressed the "envelope" and ensured it reached its proper destination.

In November of 1981, Postel posted Request for Comment (RFC) 801, the
NCP/TCP Transition Plan.  The RFC outlined a migration path from the
ARPANET's Network Computer Protocol, or NCP, to TCP/IP.  The installation
of the ARPANET itself had begun in September 1969, and it was operational
by 1971.  When Postel penned RFC 801, the ARPANET had been an operational
service for over ten years.  In the years leading up to 1981, ARPA had
sponsored research to evolve the ARPANET.  There was great interest in
digital packet broadcast radio and satellite networks.  There was also much
interest in local networks.   Although the Network Control Protocol, or
NCP, had run ARPANET since its inception, it was inadequate as a foundation
for future network growth. NCP was designed to guarantee delivery of every
data packet a user might transmit.  However, as ARPANET grew more complex
and its volume of usage increased, this built-in failsafe made the network
less scalable.  In addition, other networks were beginning to develop but
were unable to communicate with each other.

TCP, on the other hand, allowed the network to lose a packet occasionally -
without compromising the integrity of the transmission - in order to
improve the efficiency of the flow and reduce the network's vulnerability
to any disruptions (such as the link between sender and receiver).

Postel, in the RFC, noted that the Department of Defense had recently
adopted the internet "concept" and the IP and TCP were now DoD standards
for all DoD packet networks.  Computerworld, in February 1982, proclaimed
that "[T]wo communications protocols [are] expected to appear this year in
commercial DP products... [and will] allow major reductions in data
communications costs..."

By then, vendors such as Xerox and 3Com were getting on the TCP/IP
bandwagon, although some experts were cautioning that mainframe operating
systems from IBM and other major vendors were "too complex" for TCP/IP to
be added in a cost-effective manner.

In writing what was to be a kind of network independence manifesto
(declaration of network independence?), Postel took care to proclaim this
sea change with a caveat, one that is very revealing of the collaborative
culture of the nascent Internet of the day: "As with all new systems, there
will be some aspects which are not as robust and efficient as we would like
(just as with the initial ARPANET).  But with your help, these problems can
be solved and we can move into an environment with significantly broader
communication services."

Postel outlined a schedule, which called for "Full Internet Service" on
January 1, 1983.  This was specifically defined as

     All hosts are TCP-capable and use TCP-based services.  NCP is
     removed from service, relay services end, all services are
     TCP-based.

Postel had a very long-term outlook for the "new" ARPANET.  He also knew
that many developers might be tempted to advance short term goals at the
cost of long-term growth.  His caution still rings true today:

     There are some very tempting shortcuts in the implementation of IP
     and TCP.  DO NOT BE TEMPTED!  Others have and they have been
     caught!

The close of the last century was perhaps marked by a new way of telling
time, famously called Internet time by many.  Surely the Internet has
speeded up processes, relationships, and given an entirely new meaning to
"instant gratification."  However, to its credit, the Internet itself
changes on what might best be described as the antithesis of Internet time.
The Internet actually took the first 20 years, from 1973 to 1993, of its
existence to gain a foothold.  In the past ten years, 1993-2003, the
Internet assumed a place of mammoth importance in the worlds of commerce,
government and society so much so that it would be difficult to imagine a
world sans Internet today.

The secret of the Internet's success was its adherence to standards, a
philosophy which forward thinking computer scientists such as Kahn and Cerf
instilled in it.  In fact, the history of TCP is a textbook example of why
standards are of paramount importance: they should never be underestimated.
In a universe without TCP/IP, the computer world would still be searching
for its lingua franca, possibly even paralyzed by a babel of strange and
unintelligible languages.

Jonathan B. Spira is the CEO and Chief Analyst at Basex, a research and
consulting firm based in New York City.

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