1. Networks
A network is a collection of computers and devices connected together via communications devices and transmission media
Advantages of a network include:
Facilitating communications
Sharing hardware
Sharing data and information
Sharing software
Transferring funds

3. Bandwidth Measurement of the capacity of the channel Categories
Voiceband also known as low bandwidth
Medium band
Broadband
Used for high capacity transmission
Used by DSL, cable, and satellite
Several technical matters affect data communications
One is bandwidth – bits-per-second (bps) transmission capability of a channel
Three types:
Voiceband – also known as low bandwidth; standard phone line; too slow for many types of transmissions – especially high-quality video; typical speeds are 56 to 96 kbps
Medium band – with special leased lines to connect minicomputers and mainframes as well as to transmit data over long distances (for larger computer systems); not typically used by individuals
Broadband – used for high-capacity transmissions (DSL, cable, satellite connections); specialized high-speed devices; effectively transmits high-quality video and other communication needs; typically 1.5 mbps; higher speeds possible

4. Protocols Set of communication rules
Standard for Internet: TCP/IP (Transmission control protocol/Internet protocol)
Identification
Reformatting
Rules for exchanging data between computers
Essential features of protocol
Identification - Identifying sending and receiving devices (IP address); (key term) Internet unique number address; domain name server (DNS) (key term) converts text-based addresses to IP addresses
Reformatting – allows message to be broken into so easier to transmit over Internet through various interconnected networks; allows message to be reassembled at destination

5. Network Classifications
Local area networks (LAN)
Home networks
WLAN (Wireless LAN)
Metropolitan area networks (MAN)
Wide area networks (WAN)

6. Network Classifications
A local area network (LAN) is a network that connects computers and devices in a limited geographical area
A wireless LAN (WLAN) is a LAN that uses no physical wires

7. Network Classifications
A metropolitan area network (MAN) connects LANs in a metropolitan area
A wide area network (WAN) is a network that covers a large geographical area

8. Network Architecture
The design of computers, devices, and media on a network is sometimes called the network architecture
Client/server
Peer-to-peer
Terminal

9. Peer-to-peer (P2P) Model
Client/Server Model
Client
Server
Peer
Peer
Peers communicate as equals on a one-to-one basis.
Server must be prepared to serve multiple clients at any time.

10. The Client/Server Model
When processes need to communicate:
Examples:
file server
mail server
web server =>

11. The Client/Server Model (continued)
Client & server have strictly defined roles:
client sends request – then waits for answer
server accepts request – processes & returns answer
Protocols, defining how to:
encode messages
address messages
handle sending and receiving
Protocols: Example
http, ftp

12. The Peer-to-peer Model
P2P describes an Internet network on which users access each other’s hard disks and exchange files directly over the Internet

13. Network Topology
A network topology refers to the layout of the computers and devices in a communications network
Star network
Bus network
Ring network

14. Network Topology
Network topology is the layout pattern of interconnections of the various elements (links, nodes, etc.) of a computer.
Types of network topology
Star
Bus
Ring
Hierarchical
Networks are connections of two or more computers that work together to exchange information and share resources
The network architecture describes how the network is arranged and how the resources are coordinated and shared
Network architecture also describes how a computer network is configured and what strategies are used
 Topology – network arrangement or configuration

15. Star Network Smaller computers linked to a central unit
Central unit is called the network hub
Control is maintained by polling
Host computer – large centralized computer, usually a mainframe
Star network (Key Term) – nodes are connected to a single computer called a network hub
All communications pass through the hub/host computer; each connecting device is asked (“polled”) whether it has a message to send and then each device is in turn allowed to send its message
Can be used as a time-sharing system (key term)

16. Bus Network Each device handles its own communication control
There is no host computer
Has a common connecting cable called a backbone
Bus network (key term)– each device handles its own communications control
No host computer
Common connecting cable called a bus or backbone
Not as efficient as star, but it is low cost and widely used

17. Ring Network Each device is connected to two other devices
No central file server or computer
Useful in a decentralized environment
Ring network (key term)
Each device connected to two others forming a ring
No central files server or computer
Messages passed around ring until reach correct destination
Often used to link mainframes—especially over wide geographical areas
Useful in decentralized organization
Makes possible distributed data processing system (key term)
Computers can perform processing tasks on own
Can also share programs, data, and other resources

18. Hierarchical Network Several computers linked to a central host
Computers are hosts to other computers
Useful in centralized organizations
Hierarchical Network (key term)
Sometime called hybrid network
Consists of several computers linked to central host computer
All computers can server as hosts to other computers (unlike star network)
Host at top could be mainframe; computers below could be minis; then “down” to micros
Useful in centralized organization
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19. Principal Network Configurations
No instructor notes

20. Network Communications Standards
Ethernet
Token ring
TCP/IP
Wi-Fi
Bluetooth
UWB
IrDA
RFID
WiMAX
WAP

21. Network Communications Standards
Ethernet is a network standard that specifies no computer controls when data can be transmitted
The token ring standard specifies that computers and devices on the network share or pass a special signal (token)
TCP/IP is a network standard that defines how messages are routed from one end of a network to another

22. Network Communications Standards

23. Network Communications Standards
Wi-Fi identifies any network based on the standard that facilitates wireless communication
Sometimes referred to as wireless Ethernet

24. Network Communications Standards
Bluetooth defines how two Bluetooth devices use short-range radio waves to transmit data
UWB (ultra-wideband) specifies how two UWB devices use short-range radio waves to communicate at high speeds
IrDA transmits data wirelessly via infrared (IR) light waves
RFID uses radio signals to communicate with a tag placed in or attached to an object, animal, or person

25. Network Communications Standards

26. Network Communications Standards
WiMAX (802.16)
Developed by IEEE
Towers can cover a 30-mile radius
Two types are fixed wireless and mobile wireless
Provides wireless broadband Internet access
Wireless Application Protocol (WAP)
Specifies how some mobile devices can display the content of Internet services
Web
Chat rooms
Uses a client/server network

27. Communications Software
Communications software consists of programs that:
Help users establish a connection to another computer or network
Manage the transmission of data, instructions, and information
Provide an interface for users to communicate with one another

28. Communications Over the Telephone Network
The public switched telephone network (PSTN) is the worldwide telephone system

29. Communications Over the Telephone Network
Dial-up lines
Dedicated line
ISDN line
DSL
FTTP
T-carrier line
ATM

30. Communications Over the Telephone Network

31. Communications Over the Telephone Network
ADSL connections transmit data downstream at a much faster rate than upstream

32. Home Networks
Home networks provide computers with the following capabilities:
Connect to the Internet at the same time
Share a single high-speed Internet connection
Access files and programs on other computers
Share peripherals
Play multiplayer games
Connect game consoles to the Internet
Subscribe to and use VoIP

33. Home Networks

34. Organizational Internets
Intranets
Private network within an organization
Provides information to employees
Extranets
Private network that connects organizations
Used to allow suppliers and others access
Firewalls
Security system
Protects against external threats
Intranet – Intranets use browsers, Web sites, and Web pages like the public Internet; typically include , mailing lists, newsgroups, and FTP services
Extranet – Purpose is to increase efficiency and reduce costs
Firewalls – Organizational firewalls include a proxy server (key term) that is a gatekeeper; all communications between the outside world and an organization must pass through the proxy server where the source and content of each communication is evaluated; end users have many of the same concerns regarding security as organizations and can use firewalls as well

35. Careers In IT Network Administrator
Manage a company’s LAN and WAN networks
Maintain hardware and software
Diagnose and repair problems
Candidates usually have a bachelor’s degree in computer science and practical experience
Annual salary is typically between $43,000 and $68,000