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Introduction

CST 415

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Topics• Definitions

• TCP/IP Internet

• Internet Services

• Networking History

• IAB

• RFC

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DefinitionsNetwork

Any collection of items tied together through some media allowing transfer from one item to the next.

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DefinitionsWhat are some networks?

– Telephone network– Utility Network– Satellite Network– Other?

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DefinitionComputer Network

A collection of computers tied together by some media to allow information exchange.

What is the simplest computer network you can think of?

What is the media used for information exchange in this network?

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DefinitionProtocol

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 communications?

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DefinitionProtocol

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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DefinitionTo have a computer network, we must have:

– At least two computers.– The two computers are tied together via some

communication media.– The communications between the computers

must behave according to some set of communication rules (the communication protocol).

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DefinitionExercise

– 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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TCP/IP InternetAlthough there are many computer

communication protocols –» NetBEUI

» ISO OSI

» etc.

The Internet is primarily based on the protocol TCP/IP (Transmission Connect Protocol/Internet Protocol)

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TCP/IP InternetThe TCP/IP Internet is an example of a “de-facto”

standard.

At the time of the Internet’s emergence, there was a competing standard ISO OSI (International Standards Organization Open Systems Interconnect).

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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TCP/IP InternetAs has been seen in many other areas of computer

technology, the ISO Standards Committee attempted to define a protocol that was “something for everybody”.

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• Internet Services are based on protocols.

– Application-Level Services (Application Layer)» 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• Internet Services are based on protocols.

– Network-Level Services (Network Layer)» Connectionless Packet Delivery

Packets are delivered through what is known as a virtual circuit.

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 sent.

Applications do not need to worry about checking delivery status and buffering data until it is all delivered.

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Internet Services• TCP/IP Features

– Technology Independent : Drivers can be written for any underlying physical transport mechanism.

– Universal Interconnect : Any computer on the network is recognized due to a standardized address mechanism.

– End-to-end Connectivity : Messages pass from source to destination and are acknowledged as such. Intermediate routing does not change delivery.

– Standardized Applications : e-mail, ftp, etc.

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Historical PerspectiveYear Event1966 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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Historical Perspective

Internet growth from 1981 through 2000 plotted on a log scale illustrates the exponential growth.

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IABThe IAB (Internet Architecture Board) was founded

in 1983 to oversee the coordination of the TCP/IP protocol suite.

Goals:• Encourage exchange of ideas.• Focus common objectives for research activities.• Control direction of network based technologies

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RFCInternet Requests For Comments

• A series to technical papers covering the TCP/IP Protocol suite.

• 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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RFCBy 1989, the work in networking had become so

large that the informal RFC method for communication and standardization no longer worked.

Two groups were introduced:• IRTF (Internet Research Task Force) : concentrates on long

term research.

• IETF (Internet Engineering Task Force) : concentrate on short-term engineering issues.

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RFCTo get a standard:

1. The basic idea must be explained in an RFC.

2. The RFC must generate enough interest to warrant consideration.

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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RFC

The 802 working groups. The important ones are marked with *. The ones marked with are hibernating. The one marked with † gave up.