Understanding Technology and Information

Technology Revolution

• In the 18th century, mechanical systems were the focus
• The 19th century saw the rise of the steam engine
• The 20th century was defined by information, characterized by gathering, distribution, processing, and creating
• The 21st century is defined by networks, supporting human-to-human and machine-to-machine

Information Gathering

• Information is collected from sources like books, websites, interviews, and surveys
• The goal is to understand a topic or issue by collecting a range of data

Information Distribution

• Involves sharing data and information among individuals, groups, or parts of an organization
• Facilitates communication and knowledge sharing across an entire network

Information Processing

• Involves several steps consisting of acquiring, inputting, validating, manipulating, storing, outputting, communicating, retrieving and disposing of new data

Information Creation

• Converts raw data into meaningful information which relies on presenting data in a way that the recipient understands
• This conversion requires processing and organizing data to create actionable knowledge

What is a Computer Network

• Consists of communication elements connected by communication links

Communication Elements

• Include devices such as computers, printers, mobile phones, routers, and switches

Communication Links

• Include optic fiber, coaxial cable, twisted pair cables, and wireless connections like radio, microwave, and satellite

Network Topologies

• Common network arrangements include: Ring, Star, Bus, Tree, and Mesh

Computer Network Infrastructure

• Requires a combination of hardware and software for effective operation

Computer Network Resource Sharing

• Allows sharing of data, files, computing power, and video resources

Information Highway

• Enables communication among geographically dispersed users
• Facilitates connectivity and collaboration across distances

Electronic Society

• Includes Cyberspace, the virtual environment for online interaction
• Encompasses a Virtual Global Nation, where digital interactions form social structures

Computer Networks - Key Concepts

• Collection of interconnected autonomous computers

Internet - Key Concepts

• Characterized as a "network of networks"
• Loosely hierarchical structure

Internet Access

• Can be achieved through public Internet (shared networks) or private intranet (dedicated networks)

World Wide Web

• The WWW is a distributed system that runs on top of the Internet

Computer and Distributed Systems

• Distributed systems, also known as distributed computing, has multiple components located on different machines
• High levels of cohesiveness and transparency are required

Distributed Systems in Networks

• Software system is built on top of a network, having multiple components on multiple machines

Digital Modulation and Multiplexing

• Analog signals used to send digital information
• Digital Modulation refers to the process of converting between bits and signals
• Multiple signals often share channels, and is referred to as Multiplexing

Types of Digital Modulation and Multiplexing

• Baseband Transmission
• Frequency Division Multiplexing
• Time Division Multiplexing
• Code Division Multiplexing

Uses of Computer Networks

• Business applications
• Home applications
• Mobile users

Business Applications of Networks

• Resource sharing covering hardware, software and information
• Providing communication mediums like e-mail and videoconferencing
• Electronically doing business using B2B, B2C and e-commerce

Company Goals of Networks

• Client-server model to structure network
• Resource sharing of equipment, programs and data
• High reliability through replicated data and flexible hardware
• Saving money, mainframes are faster, but PCs are cheaper
• Scalability of mainframe networks via replacement
• Scalability of client-server networks via adding more servers
• Communications medium for separated employees

Client-Server Model

• It involves two processes which consist of the client-server model and peer-to-peer
• A communication network is needed for operation
• Describes communication between two computing entities over a network
• There must be a server providing that resource or service
• Involves request and replies

Socket Processing

• A process for clients to communicate with the server
• Port connection between the client and server is required

Socket Programming With TCP

• The client must contact the server
• Client must create a connection with the server's TCP to establish connection
• The created server TCP creates a new socket
• TCP provides reliable transfer of byets between the client and server

Home Network Applications

• Enables access to remote information
• Provides person-to-person communication
• Access to interactive entertainment
• Allows electronic commerce

Networks for People

• Include access to remote information through shopping, news and digital libraries
• Allow person-to-person communication such as with email, video conferences, and newsgroups
• Grant access to interactive entertainment, with videos, movies or TVs, along with game playing.

Peer to Peer Networks

• (P2P) network in which interconnected nodes ("peers") share resources amongst each other
• Based on the client-server model, but there are no fixed clients and server

Electronic Commerce

• Business-to-consumer (B2C), such as ordering books online
• Business-to-business (B2B), such as car manufacturer ordering tires from supplier
• Government-to-consumer (G2C), like government distributing tax forms electronically
• Consumer-to-consumer (C2C), allows auctioning of second-hand products on-line
• Peer-to-peer (P2P), allows music sharing

Mobile Network Users

• Combinations of wireless networks and mobile computing
• Combinations include wireless and mobile, wireless and non-mobile
• Non-wireless and mobile together, and non-wireless and non-mobile

Types of Networks

• Personal Area Networks (PAN)
• Local Area Networks (LAN)
• Metropolitan Area Networks (MAN)
• Wide Area Networks (WAN)

Network Hardware

• A classification of interconnected processors by scale

Personal Area Network (PAN)

• Includes devices within a square meter

Local Area Network (LAN)

• Includes devices within a room, building or campus

Metropolitan Area Network (MAN)

• Includes devices within a city

Wide Area Network (WAN)

• Includes devices within a country, continent or planet

Transmission Technology

• Broadcast Links are used to transmit radio, television and internet streams
• Point-to-Point Links are used for dedicated links between two devices

Broadcast Networks

• Use a single communication channel shared by all machines
• Types of communications includes broadcasting and multi-casting

Point-to-Point Networks

• Point-to-Point consist of many hops and routing algorithms
• Primarily used by Large Networks

Network Components

• Minimum of two computers
• Cables to connect computers, wireless communication is becoming more common
• Network Interface Card (NIC)
• "Switch" is used, Hubs are phased out of new systems
• Network Operation System (NOS) software

WLAN Specific Advantages

• Easier to add or remove work stations
• Easier to provide connections in areas with complicated cabling
• Installation is easy, needs less cables through walls and ceilings
• Networks can be accessed anywhere near an access point
• Wireless LAN allows portable buildings
• Can create movable "computer suites" using laptops

WLAN Specific Disadvantages

• Data can decrease with new wireless and access points
• Lower bandwidth, video streaming is best on wired LAN
• Security is difficult, and needs configuration
• limited range depending on used standard

Network Usage

• Centralized Computer Systems from the old days
• Computer Networks are now interconnected
• Distributed Systems come across as a coherent system to users

Network Usage Versus Distributed Systems

• Computer networks are collections of autonomous computers, single tech
• Distributed Systems provide users with a single coherent system, but not a single network

Business Applications

• Include resource sharing and making sure data/programs available online
• Bulleting board systems (BBS)
• Email
• Video conferencing
• E-commerce such as B2B, B2C

Home Applications Examples

• Access Remote Information
• Person-to-person communication
• Electronic Commerce
• Interactive Entertainment
• Ubiquitous Computing

E-Commerce Tags

• Business-to-consumer (B2C)
• Business-to-business (B2B)
• Government-to-consumer (G2C)
• Consumer-to-consumer (C2C)
• Peer-to-peer (P2P)

Internet Usage Examples

• Access to financial institutions, personalized news, information systems, science, sports + more
• Internet carries phone calls/video and also includes Facebook, chat-rooms
• Wiki For Tele-learning

Mobile Applications

• Portable offices that allows for driver/military support
• This can be in the form of m-commerce or m-learning

Social Issues with Networks

• Content on public forums with lack of censorship and regulation
• Junk Email
• Identity theft
• Ill-informed information

Classification of Networks

• Transmission Technology or Scale
• Includes: Broadcast Networks, Point-to-Point Networks or Scale

Broadcast Networks

• Have single communication channel shared by all machines
• Communication can be Unicast, Broadcast, or Multicast

Unicasting

• A single communication that links only two hosts

Broadcasting

• Uses all network communication nodes, messages are from single person

Multi-casting

• Is a type of group communication method.

Scale

• Interprocessor distance impacts communication properties: PAN, LAN, MAN, WAN

LAN (Local Area Network)

• Privately owned networks, can have up to 1km radius
• Traffic is restricted so transmission time bounded
• Transmission technology is high speed
• Topology such as bus, ring, or star (hub)

LAN Communication

• Depending on the situation can be static or dynamic

LAN Home Advantages

• Easy installation, foolproof operation and expandable capacity

MAN (Metropolitan Area Network)

• Bigger Version of LAN
• Broadcasting means connectionless data transfer so can be Cable TV or WiMAX

MAN Cable Systems

• Connectionless, so has data transferred without dedicated connection requirements

WAN Wide Area Network

• WAN has connected machines (hosts/end systems) by Subnet
• Transmissions are used, for switching and with routers in multiple lanes

Internet

• This is a Interconnected Network that has different owners and techs

Layer and Protocols

• Layer is the number of layers that are available
• Protocol is the name of and details of each layer

The Protocol and Peers

• Agreement between communicating parties
• Peers work due to communication

Network Architecture

• A set of layers and protocols

Virtual Communication

• Through the use of digital communication tools like video or email

Two Device Communication

• Communication is direct at physical layer over a stream or bits
• Package is coded and converted to make it ready

Layer Design Issues

• Addressing and channel control are used

Service Issues

• Service can be Connection-oriented with session layer
• OR Connectionless with the goal and connection established even with no connection

Service Primitives

• They can be reliable or unreliable, connection or connectionless

Five Service Primitives

• listen, command, receive, send & disconnect

Protocol and Service

• A service includes all operations
• A protocol has rules and dictates how the messages are coded

The OSI Reference Models

• Design principles and different layers
• Should be minimised info & boundaries and should have limited layers
• Has the following layer:
• Physical
• Data Link Layer
• Network Layer
• Transport Layer
• Session Layer
• Presentation Layer
• Application Layer

Reference With Protocols

• HTTP & TCP/IP
• This is an alternative approach