The Internet: Technology Background

Internet and world wide web

  • internet
    • interconnected network of thousands of networks and hundreds of millions of computers
    • links businesses, educational institutions, government agencies, and individuals
  • world wide web (web)
    • one of the internet’s most popular services
    • provides access to billions, possibly trillions, of web pages

The evolution of the internet

  • innovation phase (1961 - 1974)
    • creation of fundamental building blocks
  • institutionalization phase (1975 - 1995)
    • large institutions provide funding and legitimization
  • commercialization phase (1995 - present)
    • private corporations take over, expand internet backbone and local service

Key technology concepts

  • internet defined as network that
    • uses IP addressing
    • supports TCP/IP
    • provides services to users, in manner similar to telephone system
  • packet switching
    • slices digital messages into packets
    • sends packets along different communication paths as they become available
    • reassembles packets once they arrive at destination
    • use routers
      • special purpose computers that interconnect the computer networks that make up the internet and route packets
      • routing algorithms ensure packets take the best available path toward their destination
    • less expensive, wasteful than circuit-switching
  • TCP/IP communication protocol
    • transmission control protocol (TCP)
      • establishes connections among sending and receiving web computers
      • handles assembly of packets at point of transmission, and reassembly at receiving end
    • internet protocol (IP)
      • provides the internet’s addressing scheme
    • 4 TCP/IP layers
      • network interface layer
        • e.g. ethernet, token ring, frame relay, ATM, bluetooth, WiFi
      • internet layer
        • e.g. IP
      • transport layer
        • e.g. TCP, UDP
      • application layer
        • e.g. HTTP, Telnet, FTP, SMTP, BGP
    • OSI, a reference model, has 7 layers
    • internet addresses (IP)
      • IPv4
        • 32-bit number
        • four sets of numbers marked off by periods
          • class C address: network identified by first 3 sets, computer identified by last set
      • IPv6
        • 128-bit addresses
        • able to handle up to 1 quadrillion addresses (IPv4 can handle only 4 billion)
    • domain names
      • IP address expressed in natural language
    • domain name system (DNS)
      • allow numeric IP addresses to be expressed in natural language
    • uniform resource locator (URL)
    • dynamic host configuration protocol (DHCP)
      • port number
        • for client: 68
        • for server: 67
      • usually, we do not have a fixed IP address
  • other internet protocols and utility programs
    • internet protocols
      • HTTP
      • email: SMTP, POP3, IMAP
      • FTP, Telnet, SSL/TLS
    • utility programs
      • ping
      • tracert
  • client/server computing
    • powerful personal computers (clients) connected in network with one or more servers
    • servers perform common functions for the clients
      • storing files
      • software applications
      • access to printers, etc.
    • cloud computing model
      • firms and individuals obtain computing power and software over internet
      • services
        • infrastructure as a service (IaaS)
        • software as a service (SaaS)
        • platform as a service (PaaS)
      • public, private, and hybrid clouds
      • radically reduces costs of
        • building and operating web sites
        • infrastructure, IT support
        • hardware, software
      • drawbacks
        • security risks
        • shifts responsibility for storage and control to providers

The mobile platform

  • primary internet access is now through
    • tablets supplement PCs for mobile situations
    • smartphones are a disruptive technology
      • new processors and operating systems
  • mobile apps
    • use of mobile apps has exploded
      • most popular entertainment media, over TV
      • always present shopping tool
      • almost all top 100 brands have an app
    • platforms
      • iOS
      • Android
    • app marketplaces
      • Google Play
      • Apple’s App Store
      • Amazon’s Appstore

Internet Infrastructure

The reason of internet growth has boomed without disruption

  • client/server computing model
  • hourglass, layer architecture
    • network technology substrate
    • transport services and representation standards
    • middleware services
    • applications

Architecture

  • internet network architecture
    • internet backbone
      • comprised of fiber-optic cable: hundreds of glass strands that use light to transmit data
        • faster speed and greater bandwidth
        • thinner, lighter cables
        • less interference
        • better data security
      • tier 1 internet service provider or transit ISPs
      • numerous private networks physically connected to each other
      • undersea fiber optics, satellite links
  • 3 tiers internet
    • internet exchange points (IXPs)
      • regional hubs where tier 1 ISPs physically connect with one another and with regional tier 2 ISPs
      • tier 2 ISPs provide tier 3 ISPs with internet access
      • originally called network access points (NAPs) or metropolitan area exchanges (MAEs)
      • e.g. HKIX
    • tier 3 ISPs
      • retail providers
        • lease internet access to home owners, small businesses
        • large providers
          • Comcast, AT&T, Verizon in US
          • PCCW, Hutchison Telecom, HK Broadband in HK
        • smaller local providers in most countries
      • services
        • narrowband
        • broadband
        • digital subscriber line (DSL)
        • cable internet
        • satellite internet

Area Networks and Internet Access

Campus/corporate area networks

  • local area networks operating within single organization
    • e.g. HKU, Microsoft Corporation
  • lease internet access directly from regional and national carriers

Internet access

  • mobile internet access
    • two basic types of wireless internet access
      • telephone-based
        • e.g. mobile phones, smartphones
      • computer network-based
        • e.g. wireless local area network (WLAN) - based internet access
          • WiFi (various IEEE 802.11 standards)
            • high-speed, fixed broadband wireless LAN (WLAN)
            • wireless access point (hot spots)
            • limited range but inexpensive
          • Zigbee (for IoT), Bluetooth, BLE
          • LoRaWan -> low power WAN
  • telephone-based wireless internet access
    • currently based on 3G and 4G technologies
    • 5G will provide higher bandwidth with speeds reaching 10 Gbps or more, with much lower latency
  • intranets
    • TCP/IP network located within a single organization for communications and processing
    • used by private and government organizations for internal networks
    • all internet applications can be used in private intranets
  • the internet of things (IoT)
    • objects connected via sensors/RFID (Radio Frequency Identification) to the internet
    • smart things
    • interoperability issues and standards
    • security and privacy concerns
  • limitations and the current internet
    • bandwidth limitations
      • slow peak-hour service
    • quality of service limitations
      • latency
    • network architecture limitations
      • identical requests are processed individually
    • wired internet
      • copper and expensive fiber-optic cables
  • governance
    • Internet Corporation for Assigned Names and Numbers (ICANN)
    • Internet Engineering Task Force (IETF)
    • Internet Research Task Force (IRTF)
    • Internet Engineering Steering Group (IESG)
    • Internet Architecture Board (IAB)
    • Internet Society (ISOC)
    • Internet Governance Forum (IGF)
    • World Wide Web Consortium (W3C)
    • Internet Network Operators Groups (NOGs)

The Web

Hypertext

  • text formatted with embedded links
    • links connect documents to one another, and to other objects such as sound, video, or animation files
  • uses Hypertext Transfer Protocol (HTTP) and URLs to locate resources on the web

Markup languages

  • Hypertext Markup Language (HTML)
    • fixed set of pre-defined markup “tags” used to format text
    • controls look and feel of web pages
    • used in conjunction with Cascading Style Sheets (CSS)
    • HTML5, the new version
  • eXtensible Markup Language (XML)
    • designed to describe data and information
    • tags used are defined by user

Web servers and web clients

  • web server software
    • enables a computer to deliver web pages to clients on a network that request this service by sending an HTTP request
    • basic capabilities
      • security services
      • FTP
      • search engine
      • data capture
  • web server
    • may refer to either web server software or physical server
    • specialized servers
      • database servers
      • ad servers
  • web client
    • any computing device attached to the internet that is capable of making HTTP requests and displaying HTML pages

The internet and web

  • features on which the foundations of e-commerce are built
    • communication tools
      • email
      • messaging applications, e.g. instant messaging
      • online message boards
      • internet telephony, e.g. Voice Over Internet Protocol (VOIP)
      • video conferencing, video chatting, telepresence
    • search engines
      • identify web pages that match queries based on one or more techniques
        • keyword indexes
        • page ranking
      • also serve as
        • shopping tools
        • advertising vehicles (search engine marketing)
        • tool within e-commerce sites
      • procedure of Google
    • downloadable and streaming media
      • downloads
        • growth in broadband connections enables large media file downloads
      • streaming technologies
        • enables music, video, and other large files to be sent to users in chunks so that the file can play uninterrupted
      • podcasting
      • explosion in online video viewing
    • web 2.0 applications and services
      • base on demand of users
      • online social networks
        • services that support communication among networks of friends, peers
      • blogs
        • personal web page of chronological entries
        • enable web page publishing with no knowledge of HTML
      • wikis
        • enables doucuments to be written collectively and collaboratively
    • virtual reality and augmented reality
      • VR
        • immersing users within virtual world
        • typically uses head-mounted display (HMD)
        • e.g. Oculus Rift, Vive, PlayStation VR
      • AR
        • overplaying virtual objects over the real world, via mobile devices or HMDs
        • e.g. Pokémon GO
    • intelligent digital assistants
      • computer search engine using
        • natural language
        • conversational interface, verbal commands
        • situational awareness
      • can handle requests for appointments, flights, routes, event scheduling, and more
        • e.g. Apple’s Siri, Amazon Alexa, Google Assistant

Additional Reading