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• TCP/IP Internet
• Internet Services
• Networking History
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Any collection of items tied together through
some media allowing transfer from one item to
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What are some networks?
– Telephone network
– Utility Network
– Satellite Network
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A collection of computers tied together by some
media to allow information exchange.
What is the simplest computer network you can think
What is the media used for information exchange in
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The customs and regulations dealing with the
ceremonies and etiquette of the diplomatic
courts and others at a court or capital.
How does protocol relate to network
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In general, protocol deals with rules and
regulations that must be followed for two parties
to get along and communicate.
In data communications, protocol deals with:
– Message format
– Message sequence
– Rules governing message transfer
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To have a computer network, we must have:
– At least two computers.
– The two computers are tied together via some
– The communications between the computers
must behave according to some set of
communication rules (the communication
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– Define a media
– Given this media
» Define a method of information encoding
» Define a standard to allow
Unreliable exchange of information
Reliable exchange of information
Write your message definitions, sequencing, and rules
down. Hand this in at the beginning of next class.
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Although there are many computer
communication protocols –
» ISO OSI
The Internet is primarily based on the protocol
TCP/IP (Transmission Connect
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The TCP/IP Internet is an example of a “de-facto”
At the time of the Internet’s emergence, there was a
competing standard ISO OSI (International
Standards Organization Open Systems
ISO OSI was defined by a standards committee.
TCP/IP was developed and defined “in-place” as part
of a research project.
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As has been seen in many other areas of computer
technology, the ISO Standards Committee
attempted to define a protocol that was “something
This slowed the implementation of the standard as
well as caused it to bloat.
TCP/IP grew out of an implementation.
TCP/IP won the Internet because it was already there.
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• Internet Services are based on protocols.
– Application-Level Services (Application
» FTP (File Transfer Protocol)
» Telnet (Remote Login)
» HTTP (Hyper Text Transfer Protocol)
» POP (Post Office Protocol)
» SMTP (Simple Mail Transfer Protocol)
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• Internet Services are based on protocols.
– Network-Level Services (Network Layer)
» Connectionless Packet Delivery
Packets are delivered through what is known as a virtual
This means the path between node A and B could change
at any time during network based communication.
What are the ramifications of such a scheme?
» Reliable Stream Transport
Delivery of information is guaranteed to arrive at the
network destination end-point in the order in which it was
Applications do not need to worry about checking delivery
status and buffering data until it is all delivered.
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• TCP/IP Features
– Technology Independent : Drivers can be
written for any underlying physical transport
– Universal Interconnect : Any computer on the
network is recognized due to a standardized
– End-to-end Connectivity : Messages pass from
source to destination and are acknowledged as
such. Intermediate routing does not change
– Standardized Applications : e-mail, ftp, etc.
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1966 ARPA packet-switching experimentation done
1969 First ARPANET nodes go operational.
1972 Network based e-mail written by Ray Tomlinson and brought on-line.
1973 First non-US computer linked to the ARPANET
1975 ARPANET transferred to the DOD to become DARPANET.
1980 TCP/IP protocol experimentation begins
1981 Every 20 days, a now host computer is added to the DARPANET.
1983 DARPANET is switched over to use the new TCP/IP protocol suite.
1986 NSF funds and creates the NSFnet to connect 6 supercomputer centers.
1990 ARPANET is retired
1991 Gopher introduced, WWW invented, PGP released
1992 Mosaic released after being developed by Mark Andreasson et. al. at NCSA.
1995 Internet backbone goes private.
1996 OC-3 (155 Mbps) backbone built.
1998 Number of registered domain names exceeds 2 million
2000 Number of indexable web pages exceeds 1 billion. – currently at 11.5 billion
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Internet growth from
1981 through 2000
plotted on a log scale
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The IAB (Internet Architecture Board) was founded
in 1983 to oversee the coordination of the TCP/IP
• Encourage exchange of ideas.
• Focus common objectives for research activities.
• Control direction of network based technologies
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Internet Requests For Comments
• A series to technical papers covering the TCP/IP
• These papers chronicle the work done on the
TCP/IP protocol standard as well as work intended
for future research.
• RFCs are located at http://www.rfc-editor.org
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By 1989, the work in networking had become so
large that the informal RFC method for
communication and standardization no longer
Two groups were introduced:
• IRTF (Internet Research Task Force) : concentrates on long
• IETF (Internet Engineering Task Force) : concentrate on
short-term engineering issues.
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To get a standard:
1. The basic idea must be explained in an RFC.
2. The RFC must generate enough interest to warrant
3. The RFC will then be advanced to a Draft Standard.
4. A reference implementation must be produced and tested.
5. If the software is sound and the idea works, the IAB will
advance the Draft Standard to become a Standard.
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The 802 working groups. The important ones are
marked with *. The ones marked with are
hibernating. The one marked with † gave up.
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