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Lecture 6: Networking

J. S. Chou, P.E., Ph.D.National Chung Cheng University

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Human Communication

MessagesHuman communication involves the sharing of information between senders and receivers. The information is shared in the form of a message

SenderInitiates the message by formulating the message content in the brain and coding the message in a form that can be communicated to the receiver (e.g. voice)

SenderInitiates the message by formulating the message content in the brain and coding the message in a form that can be communicated to the receiver (e.g. voice)

Receiver Uses their receiving mechanism (e.g. eyes, ears) to receive the encoded message and then attempts to decode its content or requests the message be resent

Receiver Uses their receiving mechanism (e.g. eyes, ears) to receive the encoded message and then attempts to decode its content or requests the message be resent

Communication Pathway

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Human Communication Example

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Requirements for Communication (Computer)

Senders and Receivers There must a be a sender and a receiver with something to share via a message to facilitate communication

Senders and Receivers There must a be a sender and a receiver with something to share via a message to facilitate communication

Communication Medium A medium must exist between the sender and receiver over which the message travels (e.g., a cable)

Communication Medium A medium must exist between the sender and receiver over which the message travels (e.g., a cable)

ProtocolsProcedures, rules, or standards must be followed by computers when sending or receiving data

ProtocolsProcedures, rules, or standards must be followed by computers when sending or receiving data

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Communication (Human versus Computer)

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Computer Networks

Distributed Computing (1980s)The use of small computers networked together allowing users to perform a subset of tasks that in aggregate are equal to that of a centralized computer while also being able to share information between those computers

Distributed Computing (1980s)The use of small computers networked together allowing users to perform a subset of tasks that in aggregate are equal to that of a centralized computer while also being able to share information between those computers

Centralized Computing (1970s)The centralized computing model utilizes a central computer (mainframe) connected to terminals with all processing being done on the central computer

Centralized Computing (1970s)The centralized computing model utilizes a central computer (mainframe) connected to terminals with all processing being done on the central computer

Collaborative Computing (1990s)A synergistic form of distributed computing in which two or more networked computers are used to accomplish a common processing task where they are not only sharing data but also sharing processing responsibilities

Collaborative Computing (1990s)A synergistic form of distributed computing in which two or more networked computers are used to accomplish a common processing task where they are not only sharing data but also sharing processing responsibilities

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Types of ComputingDistributed Computing

Collaborative Computing

Centralized Computing

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Types of Networks

NetworksMost networks utilize a combination of computing models that have evolved over time and are connected by one or more of the following network types:

• Private Branch Exchange (PBX)• Local Area Network (LAN)• Wide Area Network (WAN)• Global Networks• Enterprise Network• Value-added Network (VAN)• Metropolitan Network (MAN)• Personal Area Network (PAN)

NetworksMost networks utilize a combination of computing models that have evolved over time and are connected by one or more of the following network types:

• Private Branch Exchange (PBX)• Local Area Network (LAN)• Wide Area Network (WAN)• Global Networks• Enterprise Network• Value-added Network (VAN)• Metropolitan Network (MAN)• Personal Area Network (PAN)

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Private Branch Exchange

PBXA telephone system serving a location by connecting one telephone line to another then to an outside telephone network. Can also connect PCs, fax, but at low phone- cable speeds

PBXA telephone system serving a location by connecting one telephone line to another then to an outside telephone network. Can also connect PCs, fax, but at low phone- cable speeds

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Network Types – Local Area Network

Local Area NetworkA computer network that spans a relatively small area allowing all computer users to connect with each other to share information and peripheral devices (e.g., printers)

Local Area NetworkA computer network that spans a relatively small area allowing all computer users to connect with each other to share information and peripheral devices (e.g., printers)

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Types of Networks – Wide Area Networks (WAN)

Wide Area Networks (WANs)A computer network that spans a relatively large area and is typically used to connect two or more LANs using different kinds of hardware and transmission media to cover large distances efficiently

Wide Area Networks (WANs)A computer network that spans a relatively large area and is typically used to connect two or more LANs using different kinds of hardware and transmission media to cover large distances efficiently

GlobalA WAN that spans multiple countries and may include the networks of several organizations (e.g. the Internet)

GlobalA WAN that spans multiple countries and may include the networks of several organizations (e.g. the Internet)

Value-added Network (VAN)A medium-speed, third-party-managed network that is economical as it is shared by multiple customer organizations that lease lines rather than investing in dedicated network equipment

Value-added Network (VAN)A medium-speed, third-party-managed network that is economical as it is shared by multiple customer organizations that lease lines rather than investing in dedicated network equipment

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Types of Networks – Wide Area Networks (WAN)Enterprise Network & MAN

EnterpriseA WAN that is the result of connecting the disparate networks of a single organization

EnterpriseA WAN that is the result of connecting the disparate networks of a single organization

Metropolitan Area (MAN) A WAN network of limited geographic scope, typically in a city-wide area that combines both LAN and high-speed fiber-optic technologies

Metropolitan Area (MAN) A WAN network of limited geographic scope, typically in a city-wide area that combines both LAN and high-speed fiber-optic technologies

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Types of Networks – Personal Area Network (PAN)

Personal Area NetworkAn emerging technology that uses wireless communication to exchange data between commuting devices using short-range radio communication (Bluetooth), typically within an area of ten meters

BluetoothIs the enabling technology of the Personal Area Network and is a specification for personal networking of desktop computers, mobile phones, pagers, portable stereos, and other handheld devices developed by its founders Ericsson, IBM, Intel, Nokia, and Toshiba

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Networking Fundamentals – Servers and Clients

ServerAny computer on a network that makes access to files, printing, communication, and other services available to users on the network

ServerAny computer on a network that makes access to files, printing, communication, and other services available to users on the network

ClientAny computer, such as a user’s workstation or a PC on the network, or software application such as word processing program that uses services provided by the server. A client only requests service and usually has only one user

ClientAny computer, such as a user’s workstation or a PC on the network, or software application such as word processing program that uses services provided by the server. A client only requests service and usually has only one user

NetworkA network consists of three separate components: servers, clients and peers

NetworkA network consists of three separate components: servers, clients and peers

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Networking Fundamentals – Peers

PeerA computer that may both request and provide services PeerA computer that may both request and provide services

Peer-to-Peer Networks (P2P)Enables any computer or device on the network to provide or request services with all peers having equivalent capabilities and responsibilities (e.g., Napster)

Peer-to-Peer Networks (P2P)Enables any computer or device on the network to provide or request services with all peers having equivalent capabilities and responsibilities (e.g., Napster)

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Networking Fundamentals - Network Services

Network ServicesThe capabilities that networked computers share through the multiple combinations of hardware and software

Network ServicesThe capabilities that networked computers share through the multiple combinations of hardware and software

File Services (a)The capabilities that networked computers share through the multiple combinations of hardware and software

File Services (a)The capabilities that networked computers share through the multiple combinations of hardware and software

Print Services (b)The capabilities used to control and manage user’s access to network printers, plotters, fax equipment, etc.

Print Services (b)The capabilities used to control and manage user’s access to network printers, plotters, fax equipment, etc.

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Networking Fundamentals - Network Services

Network Operating System (NOS)Is software that controls the network enabling computers to communicate by enabling network services

Network Operating System (NOS)Is software that controls the network enabling computers to communicate by enabling network services

Message Services (c)The capabilities that include storing, accessing, and delivering of text, binary, graphic, digitized video and audio data

Message Services (c)The capabilities that include storing, accessing, and delivering of text, binary, graphic, digitized video and audio data

Application Services (d)The capabilities that run software for network clients and enable computers to share processing power

Application Services (d)The capabilities that run software for network clients and enable computers to share processing power

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Networking Fundamentals – Media (Wireless)

WirelessA communication mechanism that has no physical transmission media, hence the name wireless, that works by transmitting electromagnetic signals through the air. Types of wireless media include:

• Infrared line of sight • High-frequency radio• Microwave methods

WirelessA communication mechanism that has no physical transmission media, hence the name wireless, that works by transmitting electromagnetic signals through the air. Types of wireless media include:

• Infrared line of sight • High-frequency radio• Microwave methods

Infrared Line of SightUses high-frequency light waves to transmit data on an unobstructed path between nodes – computers or some other device such as a printer – on a network up to 24.4 meters (i.e. most electronics remotes use this infrared light) and are susceptible to attenuation, EMI, eavesdropping, high-intensity light, and smoke

Infrared Line of SightUses high-frequency light waves to transmit data on an unobstructed path between nodes – computers or some other device such as a printer – on a network up to 24.4 meters (i.e. most electronics remotes use this infrared light) and are susceptible to attenuation, EMI, eavesdropping, high-intensity light, and smoke

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Networking Fundamentals – Media (Wireless)

High-Frequency RadioA fast transmission medium for distances up to 40 kilometers, depending on obstructions. Attenuation is very low but is susceptible to EMI and eavesdropping. Applications of this technology include pagers, cellular phones, and Wi-Fi

High-Frequency RadioA fast transmission medium for distances up to 40 kilometers, depending on obstructions. Attenuation is very low but is susceptible to EMI and eavesdropping. Applications of this technology include pagers, cellular phones, and Wi-Fi

PagersA one way, wireless messaging system in multiple typesPagersA one way, wireless messaging system in multiple types

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Networking Fundamentals – Media (Wireless)

Cellular PhoneA two-way wireless communication that assigns unique frequencies to calls and can transmit in analog or digital

Cellular PhoneA two-way wireless communication that assigns unique frequencies to calls and can transmit in analog or digital

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Networking Fundamentals – Media (Wireless)

Wireless LANs or Wireless Fidelity (Wi-Fi)Based on a standard called 802.11, this technology enables multiple computers to share Internet access, files, and peripheral devices

Wireless LANs or Wireless Fidelity (Wi-Fi)Based on a standard called 802.11, this technology enables multiple computers to share Internet access, files, and peripheral devices

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Networking Fundamentals – Media (Wireless)Wireless Media Benefits and Drawbacks

Comparisons of Wireless Media

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Network Hardware and Software (Hardware)

Modem (Modulator/Demodulator)Enables computers to connect and transmit data over phone lines by converting the sending computer’s digital signals to analog and back again for the receiving computer

Modem (Modulator/Demodulator)Enables computers to connect and transmit data over phone lines by converting the sending computer’s digital signals to analog and back again for the receiving computer

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Network Hardware and Software (Hardware)

RouterAn intelligent device used to connect two or more individual networks. When it receives a signal, it looks up the address and passes it to the appropriate network

RouterAn intelligent device used to connect two or more individual networks. When it receives a signal, it looks up the address and passes it to the appropriate network

BrouterShort for bridge router and provides the functions of bothBrouterShort for bridge router and provides the functions of both

Channel Service UnitA device that acts as a buffer between a LAN and a public carriers WAN to ensure signals placed on the public lines are appropriately timed and formed for the network

Channel Service UnitA device that acts as a buffer between a LAN and a public carriers WAN to ensure signals placed on the public lines are appropriately timed and formed for the network

GatewaysThis device performs a protocol conversion so that different networks can communicate even though they speak different languages

GatewaysThis device performs a protocol conversion so that different networks can communicate even though they speak different languages

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