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Human-Computer Interface

Human-Computer Interface. Human-Computer Interface. Course 4. Content. History of Internet What is Internet ? Internet Protocols The OSI 7 layers model TCP/IP The World Wide Web Internet Security Mail, WWW, HTTP, FTP, SSL. Internet History.

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Human-Computer Interface

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  1. Human-Computer Interface Human-Computer Interface Course 4

  2. Content • History of Internet • What is Internet ? • Internet Protocols • The OSI 7 layers model • TCP/IP • The World Wide Web • Internet Security • Mail, WWW, HTTP, FTP, SSL

  3. Internet History • 1969 – Birth of Internet - DoD project - wartime digital communications. Solution - The Defense Advanced Research Projects Agency (DARPA) launched the DARPA Internet Program • 1970 – Infancy – 1 decade of research obscurity. • 1975 – Project success=> handed to the Defense Communication Agency

  4. Internet History • 1980 – Key protocols are stable and used (IP and TCP) • 1983 – ARPANET – Internet community dominated by research and military sites. • 1983 – 562 ARPANET registered hosts. • Unix – the first operating systems implementing Internet protocols. • Late 1980 – The PC and LAN Revolution.

  5. Internet History • 1987 – The first Internet Worm appeared. • 1987 – NSFNET – backbone = T1 line connected to 170 small networks at 1.544 Mbps • Early 1990 – Internet faces the Address Exhaustion Problem – Solution CIDR = Classless Inter domain routing • Mid 1990 – Internet Exponential Growth

  6. What is Internet ? • Internet = a set of interconnected networks. • Backbone = a trunk connecting multiple access points together. • Internet communication – follows some predefined rules = communication protocols.

  7. What is Internet Internet Structure

  8. The Internet Protocols • Protocol = "a formal description of message formats and the rules two or more machines must follow to exchange those messages." • Internet communicates using multiple protocols at different levels: • IP , TCP, UDP • DNS, FTP, WWW, etc

  9. Protocol Layering • Simplifies network designs by dividing it in functional layers and assigning protocols to perform each layer's task. • Layering models: • The OSI Seven layer model • The DoD Network model (original for Internet)

  10. Dod Network Model 4 Layers • Network access • Internet IP • Host to host (TCP/UDP) • Process

  11. The OSI 7 Layer model All People Seem To Need Data Processing

  12. The TCP/IP protocol • TCP/IP the ARPANET communication protocol. • TCP/IP provides: • TCP - connection oriented reliable comm. • UDP - connectionless unreliable comm. • ICMP – error reporting and protocol diagnostic. Tightly integrated into IP.

  13. TCP/IP Addressing • Each host on the network has a UNIQUE IP address on 32 bits = 4 bytes. Ex: www.cs.ubbcluj.ro - 193.231.20.34 • 4 bytes = 232 = 4,294,967,296 • Address = Net Part + Host part.

  14. IP Address Classes • Class A (1 Byte Net Address) => (1=126).x.x.x =>126 class networks with 224-2 hosts each. • Class B => (2 bytes Net Address) => (128-191).N.x.x =>16384 Networks with 216-2 hosts. • Class C => (3 bytes Net Address)=>(192-223).N.N.x => networks with 254 hosts. • Class D => (Octet 1- 1110) – multicast • Class E => (Octet 1- 1111) - Experimental

  15. Routing • Method for choosing the path of a TCP/IP packet. • Implemented as tables • Each entry specifies the next hop. • Default entry = the next hop for non specified targets. • Each network provides a gateway that routes packets.

  16. Routing • Router = special machine implementing the routing algorithms. • Router’s tasks • Ensures that information doesn’t go where is not needed. • Ensures that information does make it to its destination

  17. Routing • Internet Routing

  18. LAN/WAN/Internet • LAN – small area network with reduced routing capabilities. Communication is based on the Ethernet’s broadcast nature. • WAN – wide area networks – based on inter-connection of multiple lines over leased lines, Fiber optic, radio links, etc. Provides and requires important routing support in order to function properly.

  19. ISPs and Internet connection

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