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Chapter 6. Telecommunications and Networks. Presentation Overview. The Evolution of Networking Data Transmission Characteristics Communications Media Network Classifications Network Topologies Network Hardware Network Software Communications Software and Protocols.

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Chapter 6

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Chapter 6

Chapter 6

Telecommunications and Networks


Presentation overview

Presentation Overview

  • The Evolution of Networking

  • Data Transmission Characteristics

  • Communications Media

  • Network Classifications

  • Network Topologies

  • Network Hardware

  • Network Software

  • Communications Software and Protocols


The evolution of networking

Telecommunications, combined use of computer hardware and communications software for sending and receiving information over communications media, enables computer users throughout the world to communicate.

The Evolution of Networking


Data transmission characteristics

Data Transmission Characteristics

What are the characteristics of transmitted data?

  • Bandwidth – number of bits that can be transferred per second over a given medium

  • Analog signals – continuous waves transmitted over a medium at a certain frequency range

  • Digital signals send data in the form of bits


Data transmission characteristics1

Bandwidth

number of bits that can be transmitted per second

terms for measuring bandwidth

Data Transmission Characteristics


Data transmission characteristics2

Analog and Digital Transmission

Modulate – sending modem changes digital signal into analog signal

Demodulate – receiving modem changes analog signal back into digital signal

Data Transmission Characteristics


Data transmission characteristics3

Translating digital signals to analog signals

Data Transmission Characteristics


Data transmission characteristics4

Internal modem – electronic board plugged into a slot on a computer’s motherboard

Data Transmission Characteristics

External modem – stand-alone device connected by cable to a computer


Data transmission characteristics5

Parallel and Serial Transmission

Serial transmission sends 1 byte plus the parity bit one bit after another in a continuous line.

Parallel transmission sends 8 bits plus a parity bit at the same time over 9 separate paths.

Data Transmission Characteristics


Communications media

Coaxial cable is an insulated center wire grounded by a shield of braided wire.

Communications Media


Communications media1

Twisted-pair cable is two parallel copper wires, individually wrapped in plastic and bound by another plastic casing.

Communications Media


Communications media2

Fiber-optic cable transmits beams of light through a glass or plastic core.

Communications Media


Communications media3

Wired Communications Media

Integrated Services Digital Network (ISDN) Lines are used to dial into the Internet and receive information at high speeds.

Digital Subscriber Lines (DSL) use existing phone lines and new switched connections to get faster speeds than traditional phone access.

T Linesare digital, high-speed, long-distance lines capable of carrying signals across the line.

Communications Media


Communications media4

Microwave systems transmit data through the atmosphere from one microwave station to another.

Communications Media


Communications media5

Communications satellite is a solar-powered, electronic device with specialized radios (transponders) for receiving signals from ground transmission stations. A satellite receives transmitted signals, amplifies them, and retransmits them to other ground locations.

Communications Media


Communications media6

Infrared technology allows data as infrared light waves to be transmitted from a special port in a computer to an infrared sensor in a printer.

Communications Media


Communications media7

Wireless Communications Media

Bluetooth technology offers short-range connectivity with other Bluetooth devices.

Devices form a small, temporary network that can transmit voice and data.

Communications Media


Communications media8

Wi-Fi-enabled devices use a broadband Internet connection through a wireless access point.

Communications Media

home


Communications media9

Signals sent by cell phones are transmitted and received from cell to cell until they reach their destination.

Communications Media


Network classifications

Network Classifications

Networking paths allow networkedclient computers to send information to a server, which relays information back to the computer or to another on the network. Fax machines and printers are shared resources. The file server accesses a shared hard disk.


Network classifications1

Network Classifications

Local area network (LAN)is a private network using a file server that houses all networkresources.


Network classifications2

Network Classifications

Wide area network (WAN)spans a large geographical area connecting two or more LANs.


Network classifications3

Network Classifications

An intranetis a network within an organization to serve internal users.


Network hardware

A network interface card (NIC) is used for wired connections in a desktop PC.

A wireless NIC allows notebook computers to use Wi-Fi hotspots.

Network Hardware

Network Interface Card (NIC)

connects each client computer to a network


Network classifications4

Network Classifications

In peer-to-peer architecture, computers act as both client and server.


Network topologies

Network Topologies

Bus Topology

  • all computers linked to a single line of cable (bus)

  • all communications travel length of bus


Network topologies1

Network Topologies

Ring Topology has no hub, and each computer is connected to two other computers in a circular path.


Network topologies2

Network Topologies

Star Topology links multiple computers and devices to a central hub in a configuration resembling a star.


Network hardware1

Network Hardware

Hubs, Switches, Routers

devices that links computers in a network


Network hardware2

Network Hardware

A gatewayis a combination of hardware and software that allows dissimilar networks to communicate.

A bridge is a combination of hardware and software that enables devices on similar networks to communicate


Network software

Network Software

Network Operating Systems (NOS)

  • controls flow of messages from client computers and provides services such as file access and printing

  • systems such as Linux and Mac OS have networking functions built in

  • Windows systems include Novell’s Netware or Windows Server software to enhance the basic operating system


Communications software

Communications Software

Communication software programs can be used to

  • access and use services of an Internet service provider for e-mail and Web browsers

  • send and receive information to and from computers through LAN and WAN networks

  • send and receive faxes


Protocols

Protocols

What are protocols?

  • Protocols are rules and procedures for exchanging information among computers on a network.

  • Computers involved must have the same settings and follow the same standards.


Communications software and protocols

Communications Software and Protocols

With simplex data transmission, data flows only one way.

With half-duplex data transmission, data flows in both directions but only in one direction at a time.

With full-duplex data transmission, data flows in both directions at the same time.


Communications software and protocols1

Communications Software and Protocols

Synchronous Transmission Protocols

blocks of bytes are wrapped in a start and stop byte called a synch byte.


Communications software and protocols2

Communications Software and Protocols

Asynchronous Transmission Protocols

each byte of data is surrounded by control bits:

  • start bit signals the beginning of a character

  • stop bit signals the end

  • parity bitchecks for errors


Communications software and protocols3

Communications Software and Protocols

Local Area Network (LAN) Protocols

  • Ethernet protocol specifies how the network is set up, how devices communicate, how problems are identified and corrected, and how components are connected.

  • Token ringprotocol sends an electronic signal (token) around the ring quickly.


Communications software and protocols4

sending

receiving

user

user

protocol

stack

layer

physical media

physical media

Communications Software and Protocols

TCP/IPTransfer Control Protocol / Internet Protocol


Communications software and protocols5

Communications Software and Protocols

Circuit Switching / Packet Switching

  • Circuit switching

  • Networks create an end-to-end circuit between the sending and receiving computers.

  • Electronic switches establish and maintain the connection.

Packet switching

  • Outgoing messages are divided into fixed-size data units called packets.

  • Packets are numbered and addressed to the receiving computer.

  • Routers examine the packets and send them to their destination.


Packet switching

Packet Switching


Communications software and protocols6

Communications Software and Protocols

Internet and Web Protocols

  • Hypertext Transfer Protocol (HTTP) is used on the World Wide Web.

    • sends small blocks (packets) of data along the Internet to their destinations

  • File Transfer Protocol (FTP)transmits and receives large files over the Internet.


Communications software and protocols7

Communications Software and Protocols

Electronic Mail Protocols

  • Post Office Protocol (POP) server allows the recipient to retrieve the message.

  • Simple Mail Transfer Protocol (SMTP) determines how a message will be routed through the Internet and then sends the message.


Communications software and protocols8

Communications Software and Protocols

Variations of the 802.11 protocol

802.11 n 2007 600 Mbps


On the horizon

On the Horizon

Based on the information presented in this chapter and your own experience, what do you think is on the horizon?


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