1. Chapter 8
Computer Networks

2. Networking and Communications Applications
Wireless phones
Cellular phones
Satellite phones
Paging and messaging
Global positioning systems (GPSs)
Satellite radio

3. Networking and Communications Applications, Cont’d.
Online conferencing (online meetings)
Videoconferencing
Web conferencing
Collaborative computing
Telecommuting
Telemedicine

4. What Is a Network and How Does it Transmit Data?
Computer network—a collection of computers and other hardware connected together to share data, hardware, software, programs, and facilitate electronic communication.

5. Data Transmission Characteristics
Analog (continuous wave) vs. digital (discreet 0s and 1s).
Bandwidth and speed (higher bandwidth allows more data to travel at the same time).
Serial vs. parallel transmission.

6. Data Transmission Characteristics, Cont’d.
Transmission directions
Simplex transmission (one way only).
Half-duplex transmission (one way at a time).
Full-duplex transmission (both ways at the same time).

7. Data Transmission Characteristics, Cont’d.
Transmission timing
Synchronous transmission
Asynchronous transmission
Isochronous transmission

8. Wired vs. Wireless Connections
With a wired network connection, the PC is physically cabled to the network.
Common in schools, business, and government facilities.
Wireless network connections allow great freedom regarding where users can use their PCs.
Increasingly common in homes, businesses, and wireless public hot spots (e.g. Starbucks).

9. Wired Network Transmission Media
Twisted-pair cable
Pairs of wires twisted together.
Used for telephone and network connections.
Coaxial cable
Thick center wire.
Used for cable TV and network connections.
Fiber-optic cable
Glass or fiber strands through which light can pass.
Used for high-speed communications.

11. Wireless Network Transmission Media
Broadcast radio transmissions (FM and AM radio broadcasts, short-range networking and wireless devices).
Microwave and satellite transmissions.
Microwave stations
Communications satellites
Cellular radio transmissions.

14. Network Topologies
Star
Bus
Ring
Combination

15. Network Architectures
Client-server networks
Client—makes requests of servers.
Server—fulfills client requests (for files, programs, Web pages, etc.).
Peer-to-peer networks (all computers at the same level)
Often takes place via the Internet.

17. LANs, WANs, and Other Types of Networks
Personal area networks (PANs)
Local area networks (LANs)
Metropolitan area networks (MANs)
Wide area networks (WANs)
Internet

18. LANs, WANs, and Other Types of Networks, Cont’d.
Intranets and extranets
Virtual private networks (VPNs)
Storage area networks (SANs)

19. Networking Hardware
Network adapters, also called network interface cards (NICs).
Needed to connect PC to network.
Come in a variety of formats (internal or external, wireless or wired, PC card, USB, etc.).

21. Networking Hardware, Cont’d.
Modems (used to connect PC to the Internet)
Conventional dial-up
ISDN
DSL
Cable
Satellite

22. Networking Hardware, Cont’d.
Hubs, switches, and routers
Wireless access points
Gateways and bridges
Repeaters
Multiplexers and concentrators

24. Communications Protocols
Communications protocol—an agreed-upon standard for transmitting data between two devices on a network.
Common wired protocols are Ethernet, Token Ring, and TCP/IP.
Common wireless protocols are (Wi-Fi), Bluetooth, and WAP.

25. Ethernet Typically used with wired LANs.
Utilizes a set of procedures (CSMA/CD) to send data and make sure it arrives.
Traditional (10Base-T) Ethernet networks run at 10 Mbps; newer 100 Mbps and 1 Gbps versions are now available.

27. Token Ring
Usually used with a ring network topology and utilizes a token to send and retrieve data.

28. TCP/IP
The protocol used with the Internet also increasingly being used with LANs.
Sends data in packets.

29. (Wi-Fi) and Bluetooth
(Wi-Fi for wireless fidelity)—a family of wireless networking standards.
802.11b is the original standard (11 Mbps).
802.11g is faster (54 Mbps) and expected to eventually replace b.
Newer versions are in development.
Bluetooth is a standard for low-cost, short-range, wireless connections between Bluetooth-enabled devices.

30. Other Networking Protocols
Wireless Application Protocol (WAP)—for Web content delivered to smart phones and other mobile devices.
IrDA—used for short range infrared data transfers.
Phoneline (Home PNA)
Powerline
Ultra Wideband (UWB)—for home multimedia delivery.

31. Network Security Issues
Unauthorized access and unauthorized use.
Hacking
War driving
Protecting against unauthorized access and use.
Possessed knowledge systems (e.g. passwords).
Possessed object systems (e.g. cards or badges).
Biometric systems (e.g fingerprint scanners or face readers).
Firewalls and other protective software.

33. Network Security Issues, Cont’d.
Computer sabotage
Computer viruses and other types of malware (e.g. computer worms and Trojan horses).
Denial of service (DoS) attacks.
Malicious spamming.
Data or program alteration.

35. Network Security Issues, Cont’d.
Protecting against computer sabotage.
Use up-to-date antivirus and firewall software.
Limit sharing disks and other removable storage media.
Only download programs from reputable Web sites.
Only open attachments that aren’t executable and are from people you know.
Regularly download and install the latest security patches available for your program and browser.

36. Summary Networking and communications applications
What is a network and how does it transmit data?
Types of networks
Networking hardware
Communications protocols
Network security issues