Internet Home networking Prof J WonKi Hong jwkhongpostech

Internet & Home networking Prof. J. Won-Ki Hong jwkhong@postech. ac. kr Dept. of Computer Science & Engineering POSTECH 1

Internet & Home Networking Contents Data Communication Network Internet & World Wide Web Home Networking 2

Internet & Home Networking Data Communication Network 3

Internet & Home Networking Brief History of Computer Networks • 1960’s – “How can we transmit bits across a communication medium efficiently and reliably? ” • 1970’s – “How can we transmit packets across a communication medium efficiently and reliably? ” • 1980’s – “How can we provide communication services across a series of interconnected networks? 4

Internet & Home Networking • 1990’s – “How can we provide high-speed, broadband communication services to support high-performance computing and multimedia applications across the globe? ” • 2000's – What do you think will dominate in the next 10 years? 5

Internet & Home Networking A Communication Model 1 2 3 4 5 6 Input Device Transmitter Source System Transmission medium Receiver Output Device Receiver Sender Input data g Transmitted Received Output data g’ Output Information or signal or signal Information m g(t) s(t) r(t) g’(t) m’ ’ Destination System 6

Internet & Home Networking Common Communication Tasks Data encoding: the process of transforming input data or signals into signals that can be transmitted Signal generation: generating appropriate electromagnetic signals to be transmitted over a transmission medium Synchronization: timing of signals between the transmitter and receiver ; when a signal begins and when it ends; duration of each signal 7

Internet & Home Networking Error detection and correction: ensuring that transmission errors are detected and corrected Flow control: ensuring that the source does not overwhelm the destination by sending data faster than the receiver can handle Multiplexing: a technique used to make more efficient use of a transmission facility. This technique is used at different levels of communication 8

Internet & Home Networking Addressing: indicating the identity of the intended destination Routing: selecting appropriate paths for data being transmitted Message formatting: conforming to the appropriate format of the message to be exchanged Security: ensuring secure message transmission Systems management: configuring the system, monitoring its status, reacting to failures and overloads, and planning for future growth 9

Internet & Home Networking Communication Network A communication network is a collection of devices connected by some communications media • Example devices are: – – – – mainframes, minicomputers, supercomputers workstations, personal computers printers, disk servers, robots X-terminals Gateways, switches, routers, bridges Cellular phone, Pager, TRS Refrigerator, Television, Video Tape Recorder 10

Internet & Home Networking • Communications Media – twisted pairs – coaxial cables – line-of-sight transmission: lasers, infra-red, microwave, radio – satellite links – fiber optics – Power line 11

Internet & Home Networking Network Structures Point-to-Point Networks • each communication line connects a pair of nodes • a packet (or message) is transmitted from one node to another • intermediate nodes, in general, receive and store entire packet and then forward to the next node • also called “store-and-forward” or “pack-switched” • some topologies: star, ring, tree 12

Internet & Home Networking Broadcast Networks • have a single communication line shared by all computers on the network • packets sent by a host are received by all computers • some topologies: bus, satellite, radio 13

Internet & Home Networking Types of Communication Networks • Local Area Networks (LANs) – – < a few km high data transmission rate (at least several Mbps) ownership usually by a single organization e. g. , Ethernet, IBM Token Ring, Token Bus, FDDI, Fast Ethernet, ATM, Gigabit Ethernet 14

Internet & Home Networking POSTECH LAN (1998. 6) 15

Internet & Home Networking POSTECH LAN (1999. 3) 16

Internet & Home Networking • Metropolitan Area Networks (MANs) – – – up to 50 km fibre optics is a popular technology for MANs may be private or public may involve a number of organizations e. g. , cable TV networks (CATV), ATM networks 17

Internet & Home Networking • Wide Area Networks (WANs) – – a few km to thousands of km point-to-point networks (also called long-haul networks) lower data transmission rate than LANs fiber optics is a popular technology for MANs ownership usually by more than a single organization – e. g. , ARPANET, MILNET (US military), CA*NET, NSFNET, KREONET, Bora. Net, KORNET, Internet 18

Internet & Home Networking Internet in Korea (1995. 5) 19

Internet & Home Networking Internet in Korea (1999. 6) 20

Internet & Home Networking Growth of Internet Users in Korea 21

Internet & Home Networking Growth of Internet Hosts in Korea 22

Internet & Home Networking Computer Communication Architecture • Computer Communication – the exchange of information between computers for the purpose of cooperative action • Computer Network – a collection of computers interconnected via a communication network 23

Internet & Home Networking • Protocol – agreement required between the communication entities and consists of three components: Syntax: data format and signal levels Semantics: control information for coordination and error handling Timing: speed matching and sequencing • Communications Architecture – a structured set of modules that implements the communication function 24

Internet & Home Networking ISO-OSI Reference Model • International Standards Organization (ISO) – Open Systems Interconnection (OSI) Reference model is a framework for connecting computers on a network • Motivation? – to reduce the complexity of networking software – as a step towards international standardization of the various protocols 25

Internet & Home Networking • The main principles applied to the OSI layered architecture are – each layer represents a layer of abstraction, – each performs a set of well-defined functions, – implementation of a layer should not affect adjacent layers, and inter-layer communication should be minimized 26

Internet & Home Networking OSI Stack Application Presentation Session Transport Network Data Link Physical 27

Internet & Home Networking Functions of the OSI Layers 1. Physical layer – responsible for the electromechanical interface to the communications media 2. Data link layer – responsible for transmission, framing and error control over a single communications link. 3. Network layer – responsible for data transfer across the network, independent of both the media comprising the underlying subnetworks and the topology of those subnetworks. 28

Internet & Home Networking 4. Transport layer – responsible for reliability and multiplexing of data transfer across the network (over and above that provided by the network layer) to the level required by the application. 5. Session layer – responsible for establishing, , and managing sessions between cooperating applications. 6. Presentation layer – responsible for providing independence to the application process from differences in data representation (syntax). 7. Application layer – ultimately responsible for managing the communications between applications. 29

Internet & Home Networking How Communication Takes Place Between the Layers • communication takes place between peer entities. • a layer provides services to the layer above it. • services are available at SAPs (Service Access Points) – analogous to telephone numbers and street addresses 30

Internet & Home Networking Relation Between Layers at an Interface IDU ICI SDU SAP ICI SDU Layer N + 1 Interface Layer N SDU Layer N entities exchange NPDUs in their layer N Protocol SAP = Service Access Point Header IDU = Interface Data Unit SDU = Service Data Unit PDU = Protocol Data Unit ICI = Interface Control Information 31

Internet & Home Networking • On the sending side: – a layer receives a PDU (Protocol Data Unit) from the layer above it, with some ICI (Interface Control Information) (such as address, data size, etc. ). – the layer ads some PCI (Protocol control Information) to the APDU and passes the enlarged PDU to the layer below along with more ICI. – A layer may also fragment a PDU into several smaller pieces to be passed separately to the layer below (in this case, the peer entity at the receiving end will reassemble the fragments). 32

Internet & Home Networking • At the receiving end: – a layer receives a PDU from the layer below. – The layer strips off the PCI added by its peer, and passes the PDU to the layer above it. – If the sending layer fragmented a PDU, its peer is responsible for reassembling it before passing it up. 33

Internet & Home Networking Other Communication Models The Anarchistic Network Model • have been used mostly in PCs The TCP/IP Model • only 5 layers exist • used mostly in Internet network applications 34

Internet & Home Networking The Anarchistic Network Model The OSI Model Application Presentation Operatin g System The TCP/IP Model Application Session Transport Network Transport Controller Data Link Physical Network the network 35

Internet & Home Networking Communication Service Types • Connection-oriented service – modeled after the telephone system – must establish a connection before use, and terminates the connection when finished. – FIFO guaranteed. – the path from the sender to receiver is fixed. – resources are pre-allocated at setup time 36

Internet & Home Networking • Connectionless service – modeled after the postal system – no connection required, but instead full addressing required in each message – FIFO not guaranteed. – the path is not fixed – resources are dynamically allocated 37

Internet & Home Networking Standards Organizations ITU-T (International Telecommunication Union Telecommunications Sector) - formerly CCITT (International Telegraph and Telephone Consultative Committee), a committee within ITU, a United Nations agency, responsible for X. 25, X. 21, X. 400, X. 500, X. 700, X. 900, etc. ISO (International Standards Organization): ISO 8073 (connection-oriented transport protocol) ANSI (American National Standard Institute) IEEE (Inst. of Electrical and Electronics Engineers): IEEE 802 38

Internet & Home Networking IETF (Internet Engineering Task Force): TCP/IP, FTP, SNMP W 3 C (World-Wide Web Consortium): HTTP, HTML, XML ATMF (ATM Forum) - ATM related standards TMF (Tele. Management Forum) - formerly known as NMF, Network Management Forum 39

Internet & Home Networking Internet and World Wide Web 40

Internet & Home Networking History of the Internet 1969 - Researchers at four US campuses create the first hosts of the ARPANET 1971 - The ARPANET grows to 23 hosts connecting universities and research centers 1973 - The ARPANET goes international with connections to England Norway 1982 - The term "Internet" is used for the first time and TCP/IP is created 1992 - Internet Society is chartered. World-Wide Web released by CERN. 41

Internet & Home Networking Definitions • A network of networks • Based on TCP/IP (Transmission Control Protocol/Internet Protocol) • A variety of services and tools 42

Internet & Home Networking Network of networks a group of two or more networks that are : • interconnected physically • capable of communicating and sharing data with each other • able to act together as a single network • virtually all of today’s computers are connected via Internet 43

Internet & Home Networking Based on TCP/IP enables the different types of machines on separate networks to communicate and exchange information. TCP/IP is • • A suite of protocols Rules for sending and receiving data across networks Addressing Management and verification 44

Internet & Home Networking Variety of services or tools The Internet offer access to data, graphics, sound, software, text, and people through a variety of services and tools for communication and data exchange • • • E-Mail Usenet FTP Gopher Telnet World Wide Web 45

Internet & Home Networking World Wide Web • A way to provide and access information resources on the Internet • Using Web Browser & Web Server • Based on HTML and HTTP • Multimedia – Hypertext "links" can lead to other documents, sounds, images, databases (like library catalogs), e-mail addresses, etc. • Non-Linear – There is no top, there is no bottom. Non-linear means you do not have to follow a hierarchical path to information resources. 46

Internet & Home Networking Web Browser • a piece of software that acts as an interface between the user and the Internet, specifically the World Wide Web • The browser acts on behalf of the user. The browser: – contacts a web server and sends a request for information – receives the information and then displays it on the user's computer • The browser can be graphical or text-based and can make the Internet easier to use and more intuitive • The helper applications are automatically invoked by the browser when a user selects a link to a resource that requires them • A Web browser can be used on most of computers 47

Internet & Home Networking Web Server • Also known as HTTP Server or HTTP Daemon • The repository of web pages of which types are HTML and any application data with MIME type • Listens for HTTP requests from the web browsers, serves those requests • Designed to communicate with web browsers using HTTP protocol • Typically runs on general purpose computer 48

Internet & Home Networking HTML • consists of standardized codes, or "tags", that are used to define the structure of information on a web page • defines several aspects of a web page including heading levels, bold, italics, images, paragraph breaks and hypertext links to other resources. • a sub-language of SGML (Standard Generalized Markup Language) that defines and standardizes the structure of documents. • standardized and portable: A document that has been prepared using HTML can be viewed using a variety of web browsers, such as Netscape and Lynx 49

Internet & Home Networking HTTP • the set of rules, or protocol, that governs the transfer of hypertext between two or more computers. • Based on Client/Server paradigm • Convey variety of Internet resources: HTML documents, text files, graphics, animation and sound • HTTP also provides access to other Internet protocols, among them: – – File Transfer Protocol (FTP) Simple Mail Transfer Protocol (SMTP) Network News Transfer Protocol (NNTP) etc. 50

Internet & Home Networking URL • • a standardized addressing scheme for Internet resources used to link documents on the Internet the browser knows where to go to get the document basic format of an URL type-of-resource: // domain. address: port/path/filename – – – ftp: //ftp. postech. ac. kr/pub/welcome. txt file: ///C|/My Documents/resume. htm news: han. protocol. http telnet: //vision. postech. ac. kr http: //www. postech. ac. kr/index. html 51

Internet & Home Networking 52

Internet & Home Networking Definition the collection of technologies and services that make it possible to connect • • PCs Network devices Appliances Security equipment 53

Internet & Home Networking Why now? Building “Internet” into consumer products is now possible • Standardization has occurred • Costs are low Low-cost, high-speed LAN and routers • Ethernet, IEEE 1394, Phone Wire, PLC, RF, etc. • Video rate networks - IEEE 1394, Gigabit Ethernet Modem and broadband networking are becoming ubiquitous Golden age of networking 54

Internet & Home Networking Technology Enablers ADSL and HFC (cable) networks • Enable broadband Internet to the home LANs, power line carrier, phone line networks, and wireless • Enable ubiquitous connectivity Internet connection sharing • Brings the Internet to everything in the home The communications software infrastructure has been determined: The Web and TCP/IP 55

Internet & Home Networking Analogous History • • Single to multiple cars per family One to multiple phones per household Multiple phone lines per house One to multiple TVs per house Mega. Trend: From one Internet device per home to MANY 56

Internet & Home Networking Roles for Home Networking Data • Extension of current use of Internet by PDAs, tablets, multiple PCs Communications • Telephony, videophone, chat, conferencing Entertainment • Games, TV, high-fidelity audio Control • Lights, HVAC, security, appliances 57

Internet & Home Networking Connecting Everything Public networks PSTN, Internet Network camera Home. PNA Phone line network Power line network Hub Web phone Printer IEEE 1394 Home. RF Communications and control Camera Entertainment Center Scanner 58

Internet & Home Networking Challenges for deployment of home network Ease of installation • There are no Net admins at home… Network configuration has to be automatic • There are no Net admins at home… Network health and recovery • There are no Net admins at home… 59

Internet & Home Networking Home Network Architecture Public networks PSTN, Internet Connection Sharing End to end broadband New media support Camera Printer 60

Internet & Home Networking Architecture for The Future Leveraging Web technologies Great standards exist today • IETF: TCP/IP, DNS, DHCP, HTTP, SSL, LDAP, IPSEC • W 3 C: HTML, XML Great services exist today • Today: e. Commerce, search • Early Stages: Internet audio/video, IP Telephony - much like early 1950 s TV • Billions of Web hits served daily Internet exists and it works 61

Internet & Home Networking TCP/IP and Web is the software infrastructure Web is evolving • HTTP v 1. 1 for performance improvements • XML extends Web for software applications – “Pages” can now be simply data – Internet Explorer 5. 0 has XML support Easy to wrap existing programs/tools/systems in Web • Programming language neutral • Contents neutral • Operating system neutral 62

Internet & Home Networking Web for “Devices” Device or service specific code Application specific size Embedded web server 20 ~ 80 K bytes code 30 ~ 90 K gates on silicon TCP/IP stack 30 ~ 90 K bytes code 30 ~ 80 K gates on silicon Ethernet, 1394 or PPP/async driver Device specific size 63

Internet & Home Networking Example Web Devices Refrigerator PC: Sharewave 64

Internet & Home Networking Example Web Devices Internet-on-a-chip design from Toshiba Semiconductor • Features: – – Network Stack - TCP, IP, UDP and PPP General Sockets - 4 - Email - SMTP, POP 3 and MIME Web - HTTPv 1. 0 and HTMLv 3. 2 (text only) Japanese and English character support • Interfaces: – – CPU Interface (Generic 80 x 86 CPU Interface) SRAM Interface Physical Layer Interface (RS 232 C & parallel port) Decoder Interface 65

Internet & Home Networking Example Web device Interactive TV from Spyglass 66

Internet & Home Networking Example Web devices Internet Router from POSTECH 67

Internet & Home Networking Conclusion 68