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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

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

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 characteristics4
Internal modem – electronic board plugged into a slot on a computer’s motherboardData 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 media1
Twisted-pair cable is two parallel copper wires, individually wrapped in plastic and bound by another plastic casing.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 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 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

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







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.
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?