What hath God wrought?

- Samuel F.B. Morse

First telegraph message on 24 May, 1844 from Supreme Court chamber in Washington, D.C. to the B&O's Mount Claire Station in Baltimore, Maryland

Communication

Telecommunication

Data Communication

Communicating devices must be part of a data communicating system (DCS), a combination of hardware and software

Data

Protocol

Sender

Receiver

Medium

Message

Simplex

Half-duplex

Full-duplex/duplex

Direction of data at time 1

Direction of data at time 2

set of devices (nodes) connected by communication links

uses distributed processing

Point to Point

Multipoint/Multidrop

refers to the way in which a network is laid out physically

geometric representation of the relationship of all the links and nodes to one another

Hub

Tap

Drop line

Repeater

Allows heterogeneous networks created by different entities to communicate

OSI (Open Systems Interconnection) model defines a seven-layer network

Internet model defines a five-layer network

internet

Internet

two or more networks that can communicate with each other

collaboration of more than thousands of interconnected networks

1967 - at an ACM meeting, Advanced Research Projects Agency presented ARPANET

small network of computers which used Interface Message Processors

1972 - Vint Cerf and Bob Kahn worked on the Internetting Project

1973 - paper on Transmission Control Protocol (TCP)

protocols to achieve end-to end delivery, encapsulation, the datagram and functions of a gateway

split into TCP and IP

TCP responsible for higher-level functions such as segmentation, reassembly and error detection

IP handles datagram routing

Autonomous Systems  (AS)

collection of routers whose prefixes and routing policies are under common administrative control

Peering - two or more autonomous networks interconnect directly with each other to exchange traffic

Transit - one autonomous network agrees to carry the traffic that flows between another autonomous network and all other network

Peering

Transit

Transit

Transit

Transit

Transit

Transit

Communication occurs between entities in different systems 

Entity - anything capable of sending or receiving information

Protocol - set of rules that govern data communications

Elements of a Protocol

Syntax - structure and format of data

Semantics - meaning of each section of bits

Timing - when data should be send and how fast they can be sent

creates and maintains an open and competitive market for manufacturers

guarantees national and international operability of data and telecommunications technology and processes

De facto ("by fact") - have not been approved by an organized body but have been adopted as standards through widespread use

De jure ("by law") - have been legislated by an officially recognized body

Standard creation committees

ISO, ITU-T, CCITT, ANSI, IEEE

Slow approval process

Forums

speeds up acceptance and use of technology

conclusions presented in standards bodies

Government Regulatory Agencies

FCC/NTC

To protect public interest

A thoroughly tested specification that is useful to and adhered to by those who work with the Internet

Specification begins as an Internet draft

work in progress, 6 month lifetime

Upon recommendation, may be published as Request for Comment

edited, assigned a number, made available to interested parties

Invented by Steve Crocker to provide record of
Network Working Group's (NWG) design of the ARPANET

RFC 1 - “Host Software”

RFC 1000 - “Request for Comments Reference Guide”