CHAPTER 4
Telecommunications &
Networking
4.1
© Prentice Hall 2002
TELECOMMUNICATIONS &
NETWORKING
• TELECOMMUNICATIONS:
Communications (both voice and data)
at a distance
• NETWORKING: Electronic linking of
geographically dispersed devices
*
4.2
© Prentice Hall 2002
THE NEED FOR NETWORKING
• SHARING OF TECHNOLOGY RESOURCES
• SHARING OF DATA
• DISTRIBUTED DATA PROCESSING AND
CLIENT/SERVER SYSTEMS
• ENHANCED COMMUNICATIONS,
INCLUDING ELECTRONIC DATA
INTERCHANGE (EDI) AND ACCESS TO
THE INTERNET
*
4.3
© Prentice Hall 2002
KEY ELEMENTS OF
TELECOMMUNICATIONS & NETWORKING
• ANALOG SIGNALS: Continuous
waveform, passes thru system. Example:
voice communications
• DIGITAL SIGNALS: Discrete waveform
two discrete states (1-bit & 0-bit, on /
off pulse). Data communication. Uses
modem to translate analog to digital, digital
to analog
*
4.4
© Prentice Hall 2002
MODEM
• ABBREVIATION FOR MODULATOR/
DEMODULATOR
• DEVICE THAT CONVERTS DATA
FROM DIGITAL FORM TO ANALOG
FORM TO BE SENT OVER ANALOG
TELEPHONE NETWORK
(RECONVERTS DATA AFTER IT HAS
BEEN TRANSMITTED)
*
4.5
© Prentice Hall 2002
SPEED OF TRANSMISSION
• BANDWIDTH: Difference between
highest and lowest frequencies (cycles per
second) that can be transmitted on a
particular medium; a capacity measure
• HERTZ: Cycles per second
• BAUD: Signals sent per second
• BITS PER SECOND (bps): Common measure
*
4.6
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TYPES OF TRANSMISSION LINES
• PRIVATE, OR DEDICATED, LINES
• SWITCHED LINES
• SIMPLEX TRANSMISSION
• HALF-DUPLEX TRANSMISSION
• FULL-DUPLEX TRANSMISSION
*
4.7
© Prentice Hall 2002
TRANSMISSION MEDIA
• TWISTED PAIR
• COAXIAL CABLE: Baseband and
broadband
• WIRELESS: Cordless phone, cellular
phone, wireless LAN, infrared devices
• SATELLITE: Microwave, line of sight
• FIBER OPTICS
*
4.8
© Prentice Hall 2002
ORBITING SATELLITES
MICROWAVE
TRANSMISSION
UPLINK
4.9
DOWNLINK
© Prentice Hall 2002
NEW SATELLITES
• OVER A DOZEN NEW PROJECTS
PROPOSED
• LOW EARTH ORBIT (LEO)
SATELLITES: Only 400 to 1000 miles above
the earth, compared to geosynchronous
satellites at 22,000 miles above the equator.
1,700 satellites to be launched by 2006
*
4.10
© Prentice Hall 2002
NEW SATELLITES
• IRIDIUM: 66 satellites offered mobile
telephony, paging, and data communications.
Bankrupt by 1999.
• TELEDESCIC: Will include 288 LEO to
provide low-cost, high-speed Internet access,
networking, teleconferencing
*
4.11
© Prentice Hall 2002
TELECOMMUNICATIONS
TRANSMISSION SPEEDS
•
•
•
•
•
•
•
•
•
Twisted pair - voice telephone
14.4 kbps -56 kbps
Twisted pair - conditioned
56 kbps - 144 kbps
Twisted pair - LAN
4 mbps - 100 mbps
Coaxial cable - baseband
10 mbps - 2 gbps
Coaxial cable - broadband
10 mbps - 550 mbps
Radio frequency wireless LAN
1 mbps - 11 mbps
Infrared light wireless LAN
4 mbps - 16 mbps
Microwave / Satellite
64 kbps - 100 mbps
Fiber optic cable
100 mbps - 100 gbps
*
4.12
© Prentice Hall 2002
TOPOLOGY OF NETWORKS
• BUS TOPOLOGY
• RING TOPOLOGY
• STAR TOPOLOGY
• TREE, OR HIERARCHICAL,
TOPOLOGY
• MESH TOPOLOGY
• MORE COMPLEX TOPOLOGIES
*
4.13
© Prentice Hall 2002
NETWORK TYPES
• COMPUTER
TELECOMMUNICATIONS NETWORK
• PRIVATE BRANCH EXCHANGE (PBX)
NETWORK
• LOCAL AREA NETWORK (LAN)
*
4.14
© Prentice Hall 2002
NETWORK TYPES
• BACKBONE NETWORK
• WIDE AREA NETWORK (WAN)
• INTERNET
*
4.15
© Prentice Hall 2002
LOCAL AREA NETWORKS
• CONTENTION BUS NETWORK: Uses
CSMA/CD protocol. Example: Ethernet
• TOKEN BUS NETWORK: Central to
Manufacturing Automation Protocol
(MAP)
• TOKEN RING NETWORK: Used in
LAN; unidirectional data flow
*
4.16
© Prentice Hall 2002
NEW LAN TECHNOLOGY
• FAST ETHERNET: Ethernet operating at
speeds up to 100 mbps
• FIBER DISTRIBUTED DATA
INTERFACE (FDDI): Token ring
architecture delivered on a dual ring at
speeds up to 100 mbps
*
4.17
© Prentice Hall 2002
BACKBONE NETWORKS
• MIDDLE DISTANCE NETWORKS:
Interconnect LANs in a single organization
with each other and with the organization’s
WAN and Internet
• EMPLOY HIGH-END LAN
TECHNOLOGY, OFTEN OPERATING
AT 100 MBPS OR MORE
*
4.18
© Prentice Hall 2002
BACKBONE NETWORK
TERMINOLOGY
• HUB: Simple device connecting one section of a
LAN to another
• BRIDGE: Connects two LAN segments when the
LANs use the same protocols
• ROUTER, OR GATEWAY: Connects two or more
LANs together. Networks may use different
protocols
• SWITCH: Connects more than two LANs that use
the same protocol into a backbone network
4.19
*
© Prentice Hall 2002
WIDE AREA NETWORKS
•
•
•
•
•
•
DIRECT DISTANCE DIALING (DDD)
WIDE AREA TELEPHONE SERVICE (WATS)
LEASED LINE: Most common, T-1 lines
SATELLITE: C-Band, KU-Band
VALUE ADDED NETWORK (VAN)
INTEGRATED SERVICES DIGITAL
NETWORK (ISDN)
*
4.20
© Prentice Hall 2002
VALUE ADDED NETWORK
(VAN)
• DATA-ONLY, PRIVATE, NONREGULATED
TELECOMMUNICATIONS NETWORK:
Uses packet switching
• AN ORGANIZATION MAY CHOOSE TO
BUY SERVICES OF A VAN TO IMPLEMENT
ITS WIDE AREA NETWORK (WAN)
*
4.21
© Prentice Hall 2002
PACKET SWITCHING
• INFORMATION DIVIDED INTO
PACKETS OF SOME FIXED LENGTH,
SENT OVER NETWORK SEPARATELY
• PERMITS MORE EFFICIENT USE OF
THE NETWORK
*
4.22
© Prentice Hall 2002
INTEGRATED SERVICES
DIGITAL NETWORK (ISDN)
• EMERGING SET OF INTERNATIONAL
STANDARDS
• USING PUBLIC TELEPHONE NETWORK
• EXTENSIVE NEW
TELECOMMUNICATIONS CAPABILITIES
• SIMULTANEOUS TRANSMISSION OF
VOICE AND DATA OVER SAME LINE TO
TELEPHONE USERS WORLDWIDE
*
4.23
© Prentice Hall 2002
USES OF ISDN
• CUSTOMER SERVICE APPLICATION:
Customer’s records automatically sent to
service representative’s workstation when
customer calls in
• SOLVES DIAL-IN PROBLEMS INTO
CORPORATE NETWORK FOR
TELECOMMUTERS, BRANCH
OFFICES
*
4.24
© Prentice Hall 2002
NEW WAN AND LAN
TECHNOLOGY
ASYNCHRONOUS TRANSFER MODE
(ATM): Switching technology employing
fast packet switching. Emerging standard for
broadband ISDN. Speeds from 1.544 mbps
to 622 mbps. Represents the future for both
LANs and WANs
*
4.25
© Prentice Hall 2002
PROTOCOL
RULES & PROCEDURES
TO GOVERN TRANSMISSION
BETWEEN COMPONENTS
IN A NETWORK
*
4.26
© Prentice Hall 2002
NETWORK PROTOCOLS
• OPEN SYSTEMS INTERCONNECTION (OSI):
Reference model, emerging standard
• TRANSMISSION CONTROL PROTOCOL /
INTERNET PROTOCOL (TCP/IP): Standard used on
the Internet
• SYSTEMS NETWORK ARCHITECTURE (SNA): IBM
standard
• FILE TRANSFER PROTOCOL (FTP): Allows file
transfer on Internet
*
4.27
© Prentice Hall 2002
INTERNET
• NETWORK OF NETWORKS THAT USE THE
TCP/IP PROTOCOL, WITH GATEWAYS
(CONNECTIONS) TO OTHER NETWORKS
THAT DO NOT USE TCP/IP
• INTERNET APPLICATIONS: e-mail,
Usenet newsgroups, listserv, FTP,
Gopher, Archie, Veronica, World Wide
Web
*
4.28
© Prentice Hall 2002
CONNECTIONS TO INTERNET
• PHONE LINE MODEM
• CABLE MODEM
• DIGITAL SUBSCRIBER LINE (DSL)
• T-1 DATA PHONE LINE
• SATELLITE
• FIBER OPTICS
*
4.29
© Prentice Hall 2002
INTRANET
• A NETWORK OPERATING WITHIN AN
ORGANIZATION EMPLOYING TCP/IP
PROTOCOL
• ORGANIZATION USES SAME WEB
BROWSER, CRAWLER, SERVER SOFTWARE
AS IT WOULD ON THE INTERNET, BUT
INTRANET IS NOT ACCESSIBLE FROM
OUTSIDE THE ORGANIZATION
*
4.30
© Prentice Hall 2002
CONNECTIVITY
MEASURE OF ABILITY OF
COMPUTING DEVICES TO PASS &
SHARE INFORMATION WITHOUT
HUMAN INTERVENTION
OPEN SYSTEMS: Software able to
function on different computer
platforms. Nonproprietary operating
systems, applications, protocols
*
4.31
© Prentice Hall 2002
INTERNET 2
•
•
•
•
WILL REPLACE INTERNET
LEADING-EDGE NETWORK CAPABILITY
HIGH-PERFORMANCE APPLICATIONS
RAPID TRANSFER OF SERVICES,
APPLICATIONS TO BROADER INTERNET
COMMUNITY
*
4.32
© Prentice Hall 2002
CHAPTER 4
Telecommunications &
Networking
4.33
© Prentice Hall 2002