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Internet & Home networking. Prof. J. Won-Ki Hong [email protected] Dept. of Computer Science & Engineering POSTECH. Contents. Data Communication Network Internet & World Wide Web Home Networking. Data Communication Network. Brief History of Computer Networks.

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internet home networking

Internet & Home networking

Prof. J. Won-Ki Hong

[email protected]

Dept. of Computer Science & Engineering

POSTECH

contents
Contents
  • Data Communication Network
  • Internet & World Wide Web
  • Home Networking
slide4

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?
slide5
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?
a communication model

1

2

3

4

5

6

Input

Information

m

Input data g

or signal

g(t)

Transmitted

signal

s(t)

Received

signal

r(t)

Output data g’

or signal

g’(t)

Output

Information

m’

Transmission

Input

Output

Sender

Receiver

Transmitter

Receiver

Device

medium

Device

Source System

Destination System

A Communication Model
common communication tasks
Common Communication Tasks
  • Data encoding: the process of transforming input data or signals into signals that can be transmitted
  • Signal generation: generating appropriate electro-magnetic 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
slide8
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
slide9
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
communication network
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
slide11
Communications Media
    • twisted pairs
    • coaxial cables
    • line-of-sight transmission: lasers, infra-red, microwave, radio
    • satellite links
    • fiber optics
    • Power line
network structures
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
slide13
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
types of communication networks
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
slide17
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
slide18
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, BoraNet, KORNET, INET, Internet
computer communication architecture
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
slide24
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
iso osi reference model
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
slide26
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
slide27

OSI Stack

OSI Stack

OSI Stack

Application

Application

Application

Presentation

Presentation

Presentation

Session

Session

Session

Transport

Transport

Transport

Network

Network

Network

Data Link

Data Link

Data Link

Physical

Physical

Physical

slide28
Functions of the OSI Layers

1. Physical layer – responsible for the electro-mechanical 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.

slide29
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.

slide30
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
slide31

Relation Between Layers at an Interface

IDU

Layer N + 1

ICI

SDU

SAP

Interface

Layer N entities

exchange N-PDUs

in their layer N Protocol

Layer N

ICI

SDU

SAP = Service Access Point

IDU = Interface Data Unit

SDU = Service Data Unit

PDU = Protocol Data Unit

ICI = Interface Control Information

SDU

Header

slide32
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).
slide33
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.
other communication models
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
slide35

The Anarchistic

Network Model

The OSI Model

The TCP/IP Model

Application

Application

Application

Presentation

Session

Operating System

Transport

Transport

Network

Network

Data Link

Controller

Data Link

Physical

Physical

Physical

the network

communication service types
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
slide37
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
standards organizations
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
slide39
IETF (Internet Engineering Task Force): TCP/IP, FTP, SNMP
  • W3C (World-Wide Web Consortium): HTTP, HTML, XML
  • ATMF (ATM Forum) - ATM related standards
  • TMF (TeleManagement Forum) - formerly known as NMF, Network Management Forum
history of the internet
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 and 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.
definitions
Definitions
  • A network of networks
  • Based on TCP/IP (Transmission Control Protocol/Internet Protocol)
  • A variety of services and tools
network of networks
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
based on tcp ip
Based on TCP/IP
  • 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
variety of services or tools
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
world wide web
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.
web browser
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
web server
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
slide49
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
slide50
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.
slide51
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
definition
Definition
  • the collection of technologies and services that make it possible to connect
    • PCs
    • Network devices
    • Appliances
    • Security equipment
why now
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

technology enablers
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

analogous history
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

MegaTrend: From one Internet

device per home to MANY

roles for 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
connecting everything

Public networks

PSTN, Internet

Network

camera

HomePNA

Phone line network

Power line

network

Hub

Web phone

Printer

IEEE 1394

HomeRF

Entertainment

Center

Communications

and control

Camera

Scanner

Connecting Everything
challenges for deployment of home network
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…
home network architecture

Internet

Connection

Sharing

End to end

broadband

New media support

Home Network Architecture

Public networks

PSTN, Internet

Camera

Printer

architecture for the future
Architecture for The Future

Leveraging Web technologies

  • Great standards exist today
    • IETF: TCP/IP, DNS, DHCP, HTTP, SSL, LDAP, IPSEC
    • W3C: HTML, XML
  • Great services exist today
    • Today: eCommerce, search
    • Early Stages: Internet audio/video, IP Telephony - much like early 1950s TV
    • Billions of Web hits served daily

Internet exists and it works

tcp ip and web is the software infrastructure
TCP/IP and Web is the software infrastructure
  • Web is evolving
    • HTTP v1.1 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
web for devices

Device or service

specific code

Embedded web

server

20 ~ 80K bytes code

30 ~ 90K gates on silicon

TCP/IP stack

30 ~ 90K bytes code

30 ~ 80K gates on silicon

Ethernet, 1394 or

PPP/async driver

Device specific size

Web for “Devices”

Application specific size

example web devices
Example Web Devices
  • Refrigerator PC: Sharewave
example web devices65
Example Web Devices
  • Internet-on-a-chip design from Toshiba Semiconductor
    • Features:
      • Network Stack - TCP, IP, UDP and PPP
      • General Sockets - 4 - Email - SMTP, POP3 and MIME
      • Web - HTTPv1.0 and HTMLv3.2 (text only)
      • Japanese and English character support
    • Interfaces:
      • CPU Interface (Generic 80x86 CPU Interface)
      • SRAM Interface
      • Physical Layer Interface (RS232C & parallel port)
      • Decoder Interface
example web device
Example Web device
  • Interactive TV from Spyglass
example web devices67
Example Web devices

Internet Router from POSTECH

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