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Internet Building Blocks

Internet Building Blocks. Networking Basics Internet Protocols Internet Addressing Client-Server Model. Evolution of the Internet. Started as 4 machine demonstration ARPANET (UCLA, UCSB, SRI , UoU)  first packet-switched network

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Internet Building Blocks

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  1. Internet Building Blocks • Networking Basics • Internet Protocols • Internet Addressing • Client-Server Model Internet Technology

  2. Evolution of the Internet • Started as 4 machine demonstration • ARPANET (UCLA, UCSB, SRI, UoU)  first packet-switched network • With TCP/IP, homogeneous communication between heterogeneous hardware became possible. • The Internet evolved into a network of networks • an open system for sharing data • a fundamental technology for applications to communicate. Internet Technology

  3. Building Blocks of the Internet • Networking Technology • Interconnecting computers • Communication Protocols • Transmission Control Protocol / Internet Protocol • Addressing System • Domain Name System (Service) • Client-Server Paradigm • Internet Applications Internet Technology

  4. Networking Basics • Packet Switching vs. Circuit Switching • Medium for Transmission • LAN’s & WAN’s • Network Speed • Main Considerations for the Internet Internet Technology

  5. Networking Basics:Circuit and Packet Switching Circuit Switched Communication Dedicated Line Packet Switched Communication Receiver Sender Data broken up into packets Internet Technology

  6. Networking Basics:Circuit vs. Packet - Pros and Cons • A packet-switching scheme is an efficient way to handle transmissions on a connectionlessnetwork such as the Internet. • An alternative scheme, circuit-switching, is used for networks allocated for voice connections. In circuit-switching, lines in the network are shared among many users as with packet-switching, but each connection requires the dedication of a particular path for the duration of the connection. Packet Switched • More efficient resource sharing, but…. • More overhead Circuit Switched • Guaranteed capacity • Inefficient use Internet Technology

  7. Networking Basics:Packets • In reality, each “letter” is sent in a bunch of pieces • as if you had sent it one page at a time. • These pieces are packets. • Each of these packets is separately numbered and includes the Internet address of the destination. • The individual packets for a given file may travel different routes through the Internet. • When they have all arrived, they are reassembled into the original file (by the TCP layer at the receiving end). Internet Technology

  8. Networking Basics:Medium for Transmission • Copper wire (SLIP/PPP, ISDN, ADSL) • Cable • Fiber optic strands • Wireless • Infrared • Satellite • Radio Wave Internet Technology

  9. Networking Basics:Local Area Networks • Developed in 1960-1970's • Typically linked to personal computers • Reliable, fast (100 Mbps) • Intra-building connectivity • Users can print, share files, and use other services as needed through applications run on the LAN server Internet Technology

  10. Networking Basics:Wide Area Networks • Geographically dispersed network • a broader communication structure than LAN • WAN usually consists of interconnected LANs • Why not just use LAN or WAN for the Internet? • Incompatible technologies across LANs • Physical Limitations • Unreliable Delivery Internet Technology

  11. Networking Basics:Method for Data Communication • IP (Internet Protocol) • Method for Routing Data • Defines how packets reach specified destination • Best-effort delivery (i.e. connectionless, unreliable) • data corruption, lost packets can occur • Encapsulates a TCP segment in an IP packet • IP header contains the destination IP address • TCP (Transmission Control Protocol) • Responsible for ensuring reliable & accurate delivery of data • e.g., error-checking, end-to-end acknowledgement, etc. • Breaks up a file to transmit into a set of TCP “segments”. • TCP header contains sequence #, ACK, checksum Internet Technology

  12. Networking Basics:Network Speed • How fast does data travel from computer screen to computer screen? • The network is as fast as its slowest segment • Transmission medium • Routing software • Application process time • Bits per Second (BPS) • 28.8 baud modem: 28000 b/s • 10baseT Ethernet: 10,000,000 b/s (10 Mbps) • High speed Ethernet : 100,000,000 b/s (100 Mbps) • Fiber optic: 155,000,000 b/s (155 Mbps) Internet Technology

  13. Networking Basics:Main considerations for the Internet • Need homogeneous communications between heterogeneous hardware and software. • Layered Networking Structure • TCP/IP • DNS • Need efficient method of data exchange for a distributed and decentralized system • Client-Server model Internet Technology

  14. Networking Basics:Four Layer Model 14 Internet Technology

  15. Internet ProtocolsTCP/IP • Provides • reliable, in-order, end-to-end transmission of data • IP makes sure • the envelope is addressed in the same way • so that anyone could receive it • TCP is more like sending a certified letter . • You get a response that someone has received it. • TCP also makes sure that the parts of the letter are all received and are IN ORDER. Internet Technology

  16. Internet ProtocolsApplication Layer Protocols • Application layer protocols • ensure that the sender and receiver are speaking the same language, and that the letter can be interpreted • HTTP, FTP, SMTP , Telnet, SSH Telnet Protocol HyperText Transfer Protocol File Transfer Protocol Simple Mail Transfer Protocol Transmission Control Protocol Internet Protocol LAN IP Packet Internet Technology

  17. Internet: User’s View widit.slis.indiana.edu widit.knu.ac.kr 155.230.194.233 uicc.knu.ac.kr widit.kmu.ac.kr www.google.com www.naver.com Internet Technology

  18. Internet: Physical View LAN 155.230.194.233 widit.knu.ac.kr www.google.com Routers LAN uicc.knu.ac.kr www.naver.com Internet Technology

  19. Internet: Physical View 155.230.194.233 cisco.ss.knu.ac.kr Local Area Network Routers widit.knu.ac.kr Campus Network cisco.uicc.kmu.ac.kr uicc.knu.ac.kr Local Area Network Internet Technology

  20. Internet: IP Addresses 155.230.194.233 155.230.0.5 155.230.194.245 155.230.0.58 155.230.13.7 Internet Technology

  21. Internet Addressing • IP address • a unique number assigned to a host • assigned by IANA • e.g.155.230.194.245 • Hostname • a unique name assigned to a host • named by organizations • e.g. widit.knu.ac.kr • Domain name • a name assigned to an entity. • e.g. knu.ac.kr Internet Technology

  22. Internet Addressing:Domain Name System (DNS) • Hostname to IP Address mapping system • DNS servers store the name/address pair. • Applications use resolvers query DNS servers. • Main Characteristics • Hierarchical • Sub-domains on the left (e.g. lis.kmu.ac.kr) • Distributed • Authoritative name servers for each domain & sub-domains • When a DNS server is missing an entry, next server is checked • A client (resolver) must know at least 1 DNS server Internet Technology

  23. Internet Addressing: DNS is Hierarchical .edu unc.edu ncsu.edu duke.edu cs.unc.edu med.unc.edu ils.unc.edu Internet Technology

  24. Specificity Specificity Most Least Internet Addressing Hostname vs. IP Address widit.knu.ac.kr Top Level Domain 155.230.194.245 Assigned locally IANA assigned Most Least Internet Technology

  25. Fully qualified resource name Internet Addressing:Anatomy of a URL • URL stands for Universal Resource Locator • sometimes seen as Uniform Resource Locator • e.g., http://kiyang.lis.kmu.ac.kr/teaching/IT/schedule.htm Hostname Protocol Domain Item requested knu.ac.kr /~kiyang/teaching/IT/s13/schedule.htm widit. http:// • Certain protocols assume certain ports (e.g., http → port 80) • When non-standard port is use, it can be specified in the URL • - e.g., http://widit.knu.ac.kr:8800/ Internet Technology

  26. Client-Server Model • Client • The user of a service • User interface • Initiates interaction • Server • The provider of the service • Data & service warehouse • Listens for client requests • Requires a protocol that • Defines the set of interactions between client and server • Specifies the details of each interaction • Defines error conditions and resulting actions to perform Internet Technology

  27. Client-Server Architecture Client Initiates a Connection Server Waits & Responds to Incoming Connections 155.230.194.233 155.230.194.245 Application Protocol (HTTP) Client Application Server Application program running on client machine (e.g., Internet Explorer) program running on server machine (e.g., Apache Web Server) Internet Technology

  28. Client-Server Model: Overview • Servers • Can be hardware (computers) or software (programs) • One computer can run many server applications. • e.g., http (web), ftp, email, telnet, etc. • Server Address = IP address + port number • Each server application listens on a different port • e.g., http → 80, SMTP → 25, telnet → 23, ssh → 22, ftp → 21 • Clients • There can be many clients for a given application • People interface with them directly • HTTP Clients: Internet Explorer, Firefox, Chrome • Email Clients: Outlook, Pine, Lotus Notes • Telnet/SSH Clients: Putty, SSH Secure Shell Internet Technology

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