Title: Telecommunications, the Internet, Intranets, and Extranets
1Telecommunications, the Internet, Intranets, and
Extranets
2Learning Objectives
-
- Define the term telecommunications and identify
and describe the function of the components of a
telecommunications system. - Identify and briefly describe three basic data
processing strategies, including their advantages
and disadvantages.
3Learning Objectives
- Briefly describe how the Internet works,
including alternatives for connecting to it and
the role of Internet service providers. - Identify and briefly describe common Internet
services.
4Learning Objectives
- Describe the World Wide Web and the way it works,
including the use of Web browsers, search
engines, Java, and other Web tools. - Define the terms intranet and extranet and
discuss how organizations are using them. - Identify several control and management issues
associated with the use of networks.
5Telecommunication
- Electronic transmission of signals for
communications - Telecommunications device is a hardware component
that allows electronic communication to occur - Telecommunications medium carries an electronic
signal and interfaces between a sending device
and a receiving device
6Elements of a Telecommunications System
7Media Types (1)
- Twisted-pair wire cable Twisted pairs of copper
wire - Used in telephone service
- Slow transmission
- Coaxial cable Conductor wire is insulated
- Faster than twisted-pair
- Fiber-optic cable Thin strands of glass bound
together - Uses light beams
- Faster than coaxial cable
8Media Types (2)
- Microwave transmission High-frequency radio
signal - Must have unobstructed line of sight between
sender and receiver - Possible to intervene
- Cellular transmission Divide area into cells
- Each cell has a mobile telephone subscriber unit
- Possible to intervene
- Infrared transmission Signals as light waves
9Common Wiring and Cabling Types
10Common Telecommunications Devices
- Modem Translates data from digital form into
analog form (for ordinary phones) and back - MOdulation and DEModulation
- Fax modem Facsimile device but also a modem
- Multiplexer Allow several signals to be
transmitted over the same line - PBX Manages both voice and data transfer
- Switching equipment routes phone calls and
messages within the building
11Carriers and Services
- Common carriers Turk Telecom, ATT
- Switched lines
- Use switching equipment to connect one phone to
another - Switch Special purpose circuit that directs
messages in certain directions - Digital subscriber lines (DSL)
- Use existing lines to transmit signals over
500Kbps - Faster Internet access
12Costs, Advantages, and Disadvantages of Several
Line and Service Types
Line/Service Speed Cost per month Advantages Disadvantages
Standard phone line 56Kbps 10-40 Broadly available Too slow
ISDN 64-128Kbps 50-150 Faster Not available everywhere
DSL 500Kbps-1.5Mbps 20-120 Use standard line Expensive not available ew.
Cable modem 500Kbps-1.5Mbps 20-120 Use existing cable
T1 1.544 Mbps 600-1200 FAST used by corporations EXPENSIVE
Satellite 60-800Kps 30-120 Instead of cable or DSL Expensive installation
13Networks and Distributed Processing
- Computer network - communications media, devices,
and software needed to connect two or more
computer systems. - Centralized processing - processing occurs in a
single location or facility. - Decentralized processing - processing devices are
placed at various locations. - Distributed processing - computers are placed at
remote locations but are connected to each other
via telecommunications devices.
14Terminal-to-Host Connection
- Host computer has the data and the processing
power - Dumb terminal contacts host computer for jobs
15File Server Connection
- The application and database reside in host
computer. - Files transferred as a whole and processed by the
user
16Client/Server Connection
- Servers have special functionalities (database
server, program execution, etc.) - Clients request services from servers
- Clients process service results
17Network Types
- Local area network (LAN)
- Same geographic area
- Wired into office buildings (unshielded
twisted-pair) - Wide area network (WAN)
- Microwave and satellite transmission
- Long-distance calls
- International network
- Transborder data flow
- International laws
18 A Typical LAN
19A Wide Area Network
20 Connecting Computing Devices Using a Home Network
21Communications Software and Protocols
- Communications software - provides a number of
important functions in a network - Network operating system - controls the computer
systems and devices on a network and allows them
to communicate with each other - Network management software - a manager can
monitor the use of individual computers and
shared hardware - Communications protocol - rules and standards
that make communications possible
22Common Communications Protocols
Protocol Description
Open Systems Interconnection (OSI) Divides data communication into seven layers for maintenance
Transport control protocol/Internet Protocol (TCP/IP) Primary communication protocol of the Internet
Ethernet Used in LANs
Asynchronous transfer mode (ATM) Organizes data into 53-byte cells for fast transmission
802.11a Supports wireless ATM devices
Bluetooth Wireless communication for cell phones, handheld computers
802.11b (Wi-fi) Wireless communication for cell phones, handheld computers
23Use and Functioning of the Internet
24Routing Messages Over the Internet
25How the Internet Works
- Internet Protocol (IP) Set of rules to pass
packets from one computer to another - Transport Control Protocol (TCP) Set of rules to
establish and break connections - Internet Protocol Address Unique address for
each computer on the Internet - Static vs. dynamic
26U.S. Top-Level Domain Affiliations
27Three Ways to Access the Internet
28Internet Service Providers
- Organizations that provide access to the Internet
- Choose based on price, reliability, other
features (e-mail address) - Examples Superonline, E-kolay
29Internet and Telecommunications Services
30Summary of Internet Services (1)
- E-mail
- Instant messaging
- Telnet/SSH
- FTP
- Chat rooms
- Internet phone
- Internet video conferencing
31Summary of Internet Services (2)
- Shop on the Web
- Auctions http//www.gittigidiyor.com/
- Distance learning
- Music, radio on the Internet
32Common Abbreviations Used in Personal E-Mail
33Two Approaches to Electronic Data Interchange
34Public Network and Specialized Services
35The World Wide Web
36The World Wide Web
- An Internet service comprising tens of thousands
of independently owned computers that work
together as one. - Home page Cover page with text and graphics
- Hypertext markup language (HTML) Standard
language to describe Web pages
37Several Interesting Web Sites
38Sample HTML
39Search Engine
40Intranets and Extranets
41Intranets and Extranets
- Intranet an internal corporate network built
using Internet and WWW standards and products - Extranet - a network that links selected
resources of the intranet of a company with its
customers, suppliers, or other business partners - Virtual private network - a secure connection
between two points across the Internet - Firewall - a device that sits between your
internal network and the outside Internet
42Summary of Internet, Intranet, and Extranet Users
43Virtual Private Network
44Net Issues
45Privacy and Security
- Cookie Text that is put on user computer to
track Web site usage - Cryptography Converting a message into a secret
code and then back into the message - Encryption
- Digital Signature Who sent the message, did the
message change on the way?
46Cryptography
47Summary
- Networks - used to share hardware, programs, and
databases across the organization. -
- Internet - transmits data from one computer
(called a host) to another. - The Web - a collection of tens of thousands of
independently owned computers that work together
as one in an Internet service.