1. 1 Copyright © 2003 Prentice Hall, IncSlides created by Bob Koziel

2. Copyright © 2003 Prentice Hall, Inc 2 Tips for using the slide show Use MS Power Point XP to view the presentation. Earlier versions will not show the animations correctly. Slides with : Click the slide to view all of its sections and animations. Some slides need to be clicked several times. will appear once the last object on the slide has appeared. Click to go to the next slide. represents an Internet link that will take you to the Web site when you click on it. Internet connection required. Clicking on the or icon will take you to the previous or the next slide. Slides with videos or sounds: Click on the picture to view videos or listen to sounds. NEXT SLIDE I NEXT SLIDE Copyright © 2003 Prentice Hall, Inc

3. 3 Chapter 7 Networks: Communicating and Sharing Resources COMPUTERS IN YOUR FUTURE 2004 COMPUTERS IN YOUR FUTURE 2004 by Bryan Pfaffenberger and Bill Daley Chapter 7 Networks: Communicating and Sharing Resources What You Will Learn NEXT SLIDE Major types of computer networks How computer connections increase the value of an organizations information technology investment The importance of protocols in a computer network Contrast between circuit switching and packet switching, as well as their strengths and weaknesses Differences between peer-to-peer and client/server LANs The most popular LAN protocol and its benefits Business applications of WANs

4. Copyright © 2003 Prentice Hall, Inc 4 NEXT SLIDE Introducing Computer Networks A computer network consists of two or more computers linked together to exchange data and share resources.

5. Copyright © 2003 Prentice Hall, Inc 5 NEXT SLIDE Local area network (LAN) Links computers within a building or group of buildings Uses direct cables, radio, or infrared signals Wide area network Links computers separated by a few miles or thousands of miles Uses long-distance transmission media Metropolitan area network (MAN) Links computers within a major metropolitan area Uses fiber-optic cables Types of Computer Networks

6. Copyright © 2003 Prentice Hall, Inc 6 NEXT SLIDE Reduced hardware costs Users share equipment Connected people People can work together without being at the same location Groupware enables sharing of schedules and communications Networking Synergies in a Nutshell Shared applications Users share software File server enables all users to work with the same application program Building information resources Users create common pools of data that can be accessed by employees

7. Copyright © 2003 Prentice Hall, Inc 7 NEXT SLIDE Network Fundamentals Physical media used in networks:  Cables– Telephone lines, coaxial cable, microwave, satellites, wireless, and fiber optic cables connect computers.  Routers– Devices that examine the data transmitted and send it to its destination.  Switches– High speed electronic switches maintain connections between computers. Protocols– Standards that specify how network components communicate with each other.

8. Copyright © 2003 Prentice Hall, Inc 8 NEXT SLIDE Circuit switching Network creates an end- to-end circuit between the sending and receiving computers Same as voice networks Suited to voice and real- time videoconferencing Switching and Routing Techniques Packet switching Outgoing message is divided into fixed-size data units called packets Packets are numbered and addressed to receiving computer Routers examine the packets and send them to their destination

9. Copyright © 2003 Prentice Hall, Inc 9 AdvantagesDisadvantages Circuit switching Voice and real-time transmission No delivery delays Costly Need to have direct electrical connection between computers to communicate Packet switching Efficient, less expensive, reliable Will function if part of the network is down Delays in receiving packets Not ideal for real-time voice communication NEXT SLIDE Advantages and Disadvantages of Circuit and Packet Switching

10. Copyright © 2003 Prentice Hall, Inc 10 NEXT SLIDE Protocols Protocols are fixed, formalized exchanges that specify how two dissimilar network components can establish communication. Proprietary protocols– Are standards developed and protected by hardware manufacturers. All hardware is bought from same manufacturer for the network to function. Open protocols– Are nonproprietary protocols. They are established by independent organizations. Any hardware supporting the protocols will operate on the network. Protocol suite–The total package of protocols that specify how a network functions.

11. Copyright © 2003 Prentice Hall, Inc 11 NEXT SLIDE Network Architecture Network architecture is the overall design of a network. The network design is divided into layers, each of which has a function separate from that of the other layers. Protocol stack– The vertical (top to bottom) arrangement of the layers. Each layer is governed by its own set of protocols.

12. Copyright © 2003 Prentice Hall, Inc 12 NEXT SLIDE Local Area Networks (LANs) LANs connect computers and peripherals within a building or group of buildings. Users can access software, data, and peripherals. LANs require special hardware and software. Computers connected to a LAN are called workstations or nodes. Different types of LANs:  Peer-to-peer  Client-server

13. Copyright © 2003 Prentice Hall, Inc 13 NEXT SLIDE LAN Hardware and Software Hardware Network interface card (NIC)– Inserted into a computer’s expansion slot Software Operating system that supports networking (Unix, Linux, Windows, Mac OS) Additional system software

14. Copyright © 2003 Prentice Hall, Inc 14 NEXT SLIDE Peer-to-Peer Networks All computers on the network are treated as equal. There are no file servers. Users decide which files and peripherals to share. They aren’t suited for networks with many computers. They are easy to set up. Example: Home networks

15. Copyright © 2003 Prentice Hall, Inc 15 NEXT SLIDE Client-Server Networks Typical corporate networks are client-server. They use various topologies or physical layouts. The network requires file servers, networked computers (clients), and a network operating system (NOS). Clients send requests to servers for programs and data, and to access peripherals.

16. Copyright © 2003 Prentice Hall, Inc 16 Network Media NEXT SLIDE LANs use a variety of media to carry network signals. Twisted pair–Two insulated wires twisted around each other. The same type of wire as that used for telephones. Coaxial cable– Consists of an insulated center wire surrounded by a layer of braided wire. The same type of wire as that used for cable TV. Fiber-optic cable– A type of fiber glass cable that transmits data in the form of light impulses. It can carry more data for longer distances than other wire. Infrared– A wireless system that includes a transmitter and receiver for sending and receiving signals. Radio– A wireless system that uses radio signals to send and receive data.

17. Copyright © 2003 Prentice Hall, Inc 17 LAN Topologies The physical layout of a LAN is called its topology. Topologies resolve the problem of contention, which occurs when multiple users try to access the LAN at the same time. Collisions or corrupt data occur when different computers use the network at the same time. Bus topology Called daisy chain Every workstation connected to a single bus cable Resolves collisions through contention management Difficult to add workstations Star topology Contains a hub or central wiring concentrator Easy to add workstations Resolves collisions through contention management Ring topology All workstations attached in a circular arrangement A special unit of data called a token travels around the ring Workstations can only transmit data when they possess a token NEXT SLIDE

18. Copyright © 2003 Prentice Hall, Inc 18 NEXT SLIDE LAN Technologies LAN protocols are standards that govern the layers of the protocol stack. Lower-layer protocols deal with contention between computers.  Lower-layer protocols: Ethernet LocalTalk Token ring Higher-layer protocols handle the network functions.  Higher-layer protocols: AppleTalk IPX/SPX NetBeui TCP/IP

19. Copyright © 2003 Prentice Hall, Inc 19 NEXT SLIDE Wide Area Networks (WANs) WANs are similar to long-distance telephone systems. They have a local access number called a point of presence (POP). They contain long-distance trunk lines called backbones.

20. Copyright © 2003 Prentice Hall, Inc 20 NEXT SLIDE Point of Presence (POP) A point of presence is a WAN network connection point that enables customers to access the WAN by making a local telephone call. Media used to create a connection from an organization to a POP include:  56 Kbps leased line  ISDN  ADSL  T1 line  Permanent virtual circuit (PVC)

21. Copyright © 2003 Prentice Hall, Inc 21 NEXT SLIDE Backbones Backbones are high-capacity transmission lines that carry WAN traffic. They are regional, continental, or transcontinental.

22. Copyright © 2003 Prentice Hall, Inc 22 Private Data Network Used by corporations, banks and governments Not open to the public Most secure type of WAN Virtual private network– Lines are leased to a single company NEXT SLIDE WAN Organization Internet Backbone providers charge fees to Internet Service Providers (ISPs). ISPs sell subscriptions to users. Not secure Not ideal for businesses Public Data Network (PDN) A for-profit data communications network Fees paid on a per-byte- transferred basis Good security High bandwidth

23. Copyright © 2003 Prentice Hall, Inc 23 NEXT SLIDE WAN Protocols X.25– Oldest packet switching protocol. It is used by automated teller machines and credit card authorization devices. Switched Multimegabit Data Service (SMDS)– Designed for digital phone lines. Faster data transfer rates than X.25. Asynchronous Transfer Mode (ATM)– Newer type of protocol. It is designed for digital lines.

24. Copyright © 2003 Prentice Hall, Inc 24 Electronic Data Interchange (EDI) Standards that specify how companies set up business-to-business transactions Speeds ordering, invoicing, and payments NEXT SLIDE WAN Applications LAN-to-LAN WANs used to connect LANs at two or more geographic locations Used to connect branches of a company into one network system Transaction Acquisition Information about transaction instantly relayed to corporate headquarters Uses point-of-sale (POS) terminal as cash register

25. Copyright © 2003 Prentice Hall, Inc 25 NEXT SLIDE Chapter 7 Summary 1.Computer networks link two or more computers to exchange data and share resources. 2.Three types of computer networks: A.Local area network (LAN) B.Metropolitan area network (MAN) C.Wide area network (WAN) 3.Computer networks: A.Reduce hardware costs B.Enable users to share applications C.Provide a means to pool an organization’s data D.Foster teamwork 4.Computer networks require physical media such as telephone wire, coaxial cable, infrared, and radio signals to connect the computers. 1.Computer networks link two or more computers to exchange data and share resources. 2.Three types of computer networks: A.Local area network (LAN) B.Metropolitan area network (MAN) C.Wide area network (WAN) 3.Computer networks: A.Reduce hardware costs B.Enable users to share applications C.Provide a means to pool an organization’s data D.Foster teamwork 4.Computer networks require physical media such as telephone wire, coaxial cable, infrared, and radio signals to connect the computers.

26. Copyright © 2003 Prentice Hall, Inc 26 NEXT SLIDE Chapter 7 Summary cont. 5.Network protocols enable the network to function smoothly. 6.Data is sent through the network by switching and routing techniques. 7.LAN topologies include: A.Bus topology B.Star topology C.Ring topology 8.Wide area networks are used to link computers throughout the world. 5.Network protocols enable the network to function smoothly. 6.Data is sent through the network by switching and routing techniques. 7.LAN topologies include: A.Bus topology B.Star topology C.Ring topology 8.Wide area networks are used to link computers throughout the world.

27. Copyright © 2003 Prentice Hall, Inc 27 THE END