Week 1

The history of the internet:

1969: ARPANET (Advanced Research Projects Agency)

• Created by the U.S. Defense Department

• In 1969, the first message was sent from 2 computers

1962: IPTO (Information Processing Techniques Office)

• A branch of ARPA

• Creates the ARPANET

1969:

• ARPANET uses "packet switching"

• First 4 nodes being UCLA, UCSB, Stanford, and Univ. of Utah

1977-78:

• MODEM software created

• Computer Bulletin Board System (BBS) Created

o Made for public messaging

1983-88:

• MILNET splits off from ARPA (due to security)

• In 1984, the NSFNET (National Science Foundation) is created.

• By 1990, NSFNET replaces ARPANET

1990:

• The internet goes private

• ISPs (Internet Service Providers) get created

• One large company at the time being AOL (America Online)

1991:

• Tim Berners-Lee Creates WWW (World Wide Web)

o Made using:

• Hypertext Markup Language (html)

• Hypertext Transport Protocol (http)

• URLs (Uniform Resource Locators

1993:

• The first web browser "Netscape" is created

1996:

• 45 million users using the internet!

2002:

• Mobile phones become big

• 544.2 million users using the internet!

Telecommunication - "the exchange of information over large distances"

Data communications - "exchange of data between 2 or more devices"

5 components of data communication: • Sender

• Message

• Receiver

• Transmission media

• Protocol

Data representation: • Text - coded

• Numbers - Binary (e.x. 11110101), Hexadecimal (F5), Deimals (245)

• Images: uses RGB or YCM pixels

• Audio

• Video: Images in a set sequence presented at a certain rate

Data Flow • Simplex

• Half-duplex

• Full-duplex

Network - "an interconnection of devices capable of communication

• Made up of

o Nodes

• End nodes

§ PC, Phones, Servers

• Connecting nodes:

§ Routers, Switches, Modems

o Links

o Interfaces

• Network criteria

o Performance:

• How fast it responds/delivers

• How may users it can contain

• if there is any delay

o Reliability

• How frequent do failures occur

• How fast it can recover

o Security

• Confidentiality

• Integrity

• Availability

Types of connections: • Point-to-Point: Connection between 2 devices

• Point-to-Multipoint: One central device connecting to multiple devices

Topologies: • Mesh

o Every node is connected to eachother

o Reliable but expensive

o To calculate link and interfaces

• n(n-1)/2 = links

• n(n-1) = interfaces

• Star

• bus

o Not used in modern networks

• Ring

o Connected point-to-point forming a ring

o Used with Optical Fibre network in WANs

• Hybrid

o A combination of other topologies

o Very practical

o Seen as an extended star topology

Network Types: • PAN (Personal Area Network)

o Covers the least space, typically just a room

o E.x. a room with a computer, printer, Bluetooth speakers)

• LAN (Local Area Network)

o Typically privately owned in small office's

o E.x. two computers and a printer in an office

o Each host has an identifier address

o A sent packet from one host to another holds both the source and destination address'

of the host

• MAN (Metropolitan Area Network)

o Covers larger geographical ground then land

o Owned by business or leased by customers

• WAN (Wide Area Network)

o Covers a much larger area then LAN

• Can be town, country or region wide

o Typically used by large companies

Switching • Circuit-Switched (CS) network

o All packets go through same path

o Can waste bandwidth

• Packet Switched (PS) network:

o Packets travel through their own paths

o No bandwidth reservation

Internet standards • Internet standard - rules to be followed when working with the internet

o Made by the IETF (Internet Engineering Task Force) being 1/2 sub-organizations of the

internet society

• Internet draft - a working document with a six month lifetime

• RFC - Request for Comment

Standardization Bodies • International

o ISO (International Organization for Standardization)

• Responsible for creating international standards for a large range of industries

o ITU (International Telecommunication Union)

• Responsible to developing standards for telecommunication (Radio, satellites,

the internet, etc)

o IEC (International Electrotechnical Commission

• Responsible for standards for electrical and electronic related technologies

• Regional

o ETSI (Europe)

• Responsible for developing standards information technologies exclusively

withing europe (IoT and 5G)

• Country

o Standards Council of Canada (SCC)

• Responsible for overseeing national standards within canada

• Other

o IEEE (Institute of Electrical and Electronics Engineers)

• Responsible for developing standards for electrical and electronic technologies

(such as WI-FI)

o IETF (Internet Engineering Task Force)

• Responsible for developing internet standards (such as HTTP and TCP/IP)

o W3C (World Wide Web Consortium

• Responsible for developing standards for the world wide web (such as HTML,

CSS and overall accessibility guidelines)