Session 1. Objectives: By the end of this session, the student will be able to: Define the basic terminology of networks Recognize the individual.

Session 1

Objectives:By the end of this session, the student will be able to:

Define the basic terminology of networksRecognize the individual components of the big picture of computer networksOutline the basic network configurationsCite the reasons for using a network model & explain how they apply to current network systemsList the layers of the OSI model and describe the duties of each layerList the layers of the TCP/IP protocol suite and describe the duties of each layerCompare the OSI and TCP/IP protocol suite and list their differences and similarities

Definition of a Network

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Network“An interconnection of computers and computing equipment using either wires or radio waves over small or large geographic areas”

Direct InteractionInternetABMInteracPhone

Indirect InteractionTTCroads (driving)shopping (the store's inventory tracking system)

Definition of a Network

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Scale of a networkPAN - Personal Area Network

span several metres – laptops, PDAs, wireless

LAN – Local Area Networksspan a room, floor, building, campus

MAN -Metropolitan Area Networksup to 80km (typical city size). High-speed networks connecting businesses and businesses to Internet

WAN – Wide Area Networksspans portions of provinces, multiple provinces, countries and the world

Data and Signals

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Data and SignalsData – an aspect of information to be moved from one computer to another

Signals – the means to move the data

T E S T

http://www.anbg.gov.au/flags/semaphore.html

Data and Signals

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Data and SignalsDigital Signal

Analog Signal

Data and Signals

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Data CommunicationsTransmission of Digital Data or Analog Data over Digital or Analog Networks

Digital Network Analog NetworkDigital Data no conversion requires modem

Analog Data requires sampling, no conversionthen encoding usingdigitizer (a.k.a CODEC)

Voice Network vs. Data Network

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Voice NetworkHistorically an analog network carrying only voice (telephone calls)

Data NetworkHistorically a digital network carrying only data

Merging of the NetworksThese networks are merging with use of modems to carry data over voice networks and VoIP (Voice over IP) to carry voice (telephone calls) over data networks

Components of the Network

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Terminal/Microcomputer-to-Mainframe

Dumb TerminalTerminal without processor, limited RAM, and a modemTypically slow speedProprietary protocol

PC as a TerminalRequires emulation software, perhaps hardware as well

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Microcomputer-to-Local area network

Services providedPrinter sharing, file sharing, application sharing

Common implementation•Data on server is downloaded to PC. •PC manipulates data•PC returns data to server

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Microcomputer-to-Internet

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LAN-to-LAN

LAN-to-LAN•Share software and peripherals.•Screening information through switches for security or performance reasons

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PAN-to-Workstation

PAN-to-Workstation•PANs emerged in late 1990s.•Typically an off-line connection that requires the data repositories to periodically synchronize their data

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LAN-to-MAN

LAN-to-MAN•Typically uses fibre-optic links.•Can transmit data at LAN speeds (very fast).•Businesses use it to connect to their ISP.

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LAN-to-WAN

LAN-to-WAN•A business may wish to connect their LAN to the Internet (a WAN)•A router is used to convert the LAN data into WAN data•Modern routers can also provide some security functions

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Sensor-to-LAN

Sensor-to-LAN•Common in manufacturing environments•Connected to

– assembly lines– robotic control devices– oven temperature– chemical analysis equipment

•to data gathering computers that control movements, operations, sound alarms, etc.17

Satellite and Microwaves

Satellite and microwavesA means to connect networks over prohibitively expensive distances (using wire), or over rough terrain (mountainous regions). Both voice networks and data networks use this technology.

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Wireless Telephone

Wireless telephone (cell phone)•Newer technologies have less background noise•Can transmit limited amounts of data•Police and Emergency services use a portion of the frequency range to transmit data between laptops and central computer systems •Cellular Digital Packet Data standard governs this technology

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Components of a Network

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Components of a networkWiresPrinted circuit boardswiring connectors and jackscomputerscentrally located wiring concentratorsdisk and tape drivescomputer applicationsData communications programs for:

data transfererror checkingnetwork accessnetwork privacy

Open Systems Interconnect Model

Application LayerThe application that is using the network resides here:

•Email•file transfer•remote login•web browsing

Creates data package with message contents and addresses.

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Message and addressing


Presentation LayerMiscellaneous functions for ensuring message is presented properly to sender or receiver:

•Performs code conversion (ASCII/EBCDIC)•Encryption / Decryption•Compression/Decompression

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addressing


Session LayerLeast used layer

Responsible for•Establishing sessions between users•Token management (a software token is passed back and forth to determine which computer talks during the current session),•Synchronization points (backup points in case of errors or failures, eg transmitting a large book, and having synchronisation points at the end of each chapter)

Tokens now are usually inserted at the Application layer, possibly the Transport layer

Synchronisation now points are usually inserted at the Application layer

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addressing


Transport LayerEnsures the data packet that left the originating station is identical to the packet received at the final destination•No transmission errors•Data arrives in the same order it was transmitted•No duplication of data

Responsible for end-to-end error control and end-to-end flow control

This layer must be able to work across all kinds of networks whether thay are reliable or not

Will try to recover from error conditions and return to a known safe-state if the underlying layers experience reset or restart conditions

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addressingError detectionFlow control


End-to-end LayersThe end-to-end layers are:•Application Layer•Presentation Layer•Session Layer•Transport Layer

These four layers are responsible for the data transmitted between the end points of the network.

They are only acted on by the end points, whereas the remaining layers perform their function at each node along the network path

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Network LayerResponsible for:•Creating•Maintaining•Endingnetwork connections

As package of data is sent from node to node on the network, this layer ensures that proper addressing is added to get the packet to its next intended receiver

Applies:•Routing information to get packet through network•Performs congestion control

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addressingError DetectionFlow Control

NetworkLayer info


Data-link LayerResponsible for taking data from Network layer and transforming it into a Frame

Contains:•Identifiers that mark the beginning and ending of the frame•Control information•Address information (identifies a particular workstation in a line of mulitiple workstations)

May perform Error Control

Must perform Flow Control to ensure next workstation is not overwhelmed with too much data

Whereas the Transport Layer performs error control and flow control between end-points, Data-link Layer performs error control and flow control between each node on the path

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NetworkLayer info

Data-linkLayer info


Physical LayerHandles transmission of bits over a communications channel

Responsible for:•voltage levels•plug and connector dimensions•pin configurations•usually choice of wire or wireless media determined•other electrical and mechanical issues

As digital or analog data is encoded or modulated onto a digital or analog signal, this layer also determines the encoding technique or modulation technique.

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NetworkLayer info

Data-linkLayer info

TCP/IP Protocol Suite

Application LayerSupports network applications

Also incorporates the functions of the Presentation layer of the OSI model

Frequently used applications:•File Transfer Protocol (FTP)•Telnet•Simple Mail Transfer Protocol (SMTP)•Simple Network Management Protocol (SNMP)•Hypertext Transfer Protocol (HTTP)

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Transport LayerSimilar to OSI Transport Layer

Commonly uses TCP (Transmission Control Protocol) to maintain error-free, end-to-end connection

TCP includes:•error control information in case one packet of a sequence does not arrive at its destination•packet sequencing information so that all packets stay in the same sequence

UDP (User Datagram Protocol) is another protocol at this level, although less frequently used

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Error DetectionFlow Control


Network LayerRoughly equivalent to OSI Network Layer

However, TCP/IP uses Internet Protocol (IP) almost exclusively to transfer data between networks

Prepares a packet (a fixed-sized collection) of data so that it can move between networks on the Internet or between corporate networks.

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NetworkLayer info


Network Access LayerRoughly equivalent to OSI Data-link and Physical Layers

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NetworkLayer info

NetworkAccess Layerinfo

Request for a Web Page

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Logical / Physical Connections

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RFC Process

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RFCs are available at: http://www.ietf.org/rfc.html

RFC Process

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Process•Internet draft – worked on by 1 or more groups until ready to be published as an RFC•RFC assigned a number (proposed standard)•Implemented and tested by a number of groups- results published•If passes a minimum of two independent and interoperable implementations elevated to Draft Standard•After results of test implementations, and if no further problems, elevated to Internet Standard

Internet Bureaucracy

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Internet Society(ISOC)

Internet Architecture

Board(IAB)

Internet EngineeringTask Force

(IETF)

Internet ResearchTask Force

(IRTF)

Non-profit, international committee that provides support for the entire standards making process

Technical Adviser to ISOC

Working groups:Internet protocols, security, user services, operations, routing and network management

Long-range goals of InternetWorking groups:Architecture, technology, applications and protocols

Session 1. Objectives: By the end of this session, the student will be able to: Define the basic terminology of networks Recognize the individual.

Documents

data networks

data pc

data merging

data repositories

network model

voice networks

world slide

codec slide