Transcript Where Did TCP/IP Come From

Where Did TCP/IP
Come From
Last Update 2009.06.29
1.0.0
Copyright 2009 Kenneth M. Chipps Ph.D.
www.chipps.com
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Protocols Used in Internetworks
• Today’s internetworks rely solely on
TCP/IP for the protocols used to manage
conversations between points
• This was not always the case
• Let’s see how we got to where we are
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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NCP
• The original internetwork or network of
networks was ARPANET
• It originally used a single protocol named
NCP
• However, NCP did not have the ability to
address networks and hosts further
downstream than a destination on the
ARPANET itself
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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TCP Comes on the Scene
• Robert Kahn who had done some of the
basic work in this field decided to develop
a new version of the protocol which could
meet the needs of an open architecture
network environment
• This protocol would eventually be called
the TCP/IP - Transmission Control
Protocol/Internet Protocol
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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Requirements Set for TCP/IP
• Four ground rules were critical to Kahn's
early thinking
– Each network would have to stand on its own,
no internal changes would be required to a
network
– Communications would be on a best effort
basis
• If a packet didn't make it to the final destination, it
would be retransmitted from the source
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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Requirements Set for TCP/IP
– Black boxes would be used to connect the
networks
• There would be no information retained by the
black boxes about the individual packets passing
through them
• Thereby keeping them simple and avoiding
complicated recovery routines
– There would be no global control at the
operations level
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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Requirements Set for TCP/IP
• Other requirements included
– Algorithms to prevent lost packets from
permanently disabling communications and
enabling them to be successfully
retransmitted from the source
– The need for global addressing
– Techniques for host to host flow control
– Interfacing with the various operating systems
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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Development of TCP/IP
• In the spring of 1973 Kahn asked Vint Cerf
to work with him on the detailed design of
the protocol
• Cerf had been intimately involved in the
original NCP design and development and
already had the knowledge about
interfacing to existing operating systems
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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Development of TCP/IP
• So armed with Kahn's architectural
approach to the communications side and
with Cerf's NCP experience, they teamed
up to spell out the details of what became
TCP/IP
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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Development of TCP/IP
• The first written version of the resulting
approach was distributed at a special
meeting of the INWG - International
Network Working Group which had been
set up at a conference at Sussex
University in September 1973
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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Development of TCP/IP
• Some basic approaches emerged from
this collaboration between Kahn and Cerf
– Communication between two processes
would logically consist of a very long stream
of bytes - called octets
– The position of any octet in the stream would
be used to identify it.
– Flow control would be done by using sliding
windows and acknowledgments
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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Development of TCP/IP
– The destination could select when to
acknowledge and each ack returned would be
cumulative for all packets received to that
point
– Although Ethernet was under development at
Xerox PARC at that time, the proliferation of
LANs were not envisioned at the time, much
less PCs and workstations
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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Development of TCP/IP
– The original model was national level
networks like ARPANET of which only a
relatively small number were expected to exist
– A 32 bit IP address was used of which the first
8 bits signified the network and the remaining
24 bits designated a host on that network
– This assumption, that 256 networks would be
sufficient for the foreseeable future, was
clearly in need of reconsideration when LANs
began to appear in the late 1970s
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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Development of TCP/IP
• The original Cerf and Kahn paper on the
Internet described one protocol, called
TCP, which provided all the transport and
forwarding services in the Internet
• However, the initial effort to implement
TCP resulted in a version that only allowed
for virtual circuits
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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Development of TCP/IP
• This model worked fine for file transfer and
remote login applications, but some of the
early work on advanced network
applications, in particular packet voice in
the 1970s, made clear that in some cases
packet losses should not be corrected by
TCP, but should be left to the application
to deal with
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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Development of TCP/IP
• This led to a reorganization in 1978 of the
original TCP into two protocols, the simple
IP which provided only for addressing and
forwarding of individual packets, and the
separate TCP, which was concerned with
service features such as flow control and
recovery from lost packets
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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Development of TCP/IP
• For those applications that did not want
the services of TCP, an alternative called
UDP - User Datagram Protocol was added
in order to provide direct access to the
basic service of IP
• Much of the widespread use of TCP/IP
has come from three things besides its
excellent design
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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Deployment of TCP/IP
• TCP/IP was adopted as a defense
standard in 1982
– As such all defense related networks were
required to use it as the only protocol
standard
– Many of the original internetworks were
funded with defense related funds
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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Deployment of TCP/IP
• TCP/IP was widely distributed at low cost
to university computer science
departments
– Much of this was done by AT&T through UNIX
• ARPANET moved in mass from NCP to
TCP/IP in 1983
Copyright 2009 Kenneth M. Chipps Ph.D. www.chipps.com
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