1. Chapter 1: Computer Networks IB 300: Advanced Computer Sciences. Professor: Nabil Elmjati

2. Introduction Computer network  Computers connected together  Purpose: Exchanging resources and information  Just about any kind of information can be sent Examples: Television and radio signals, voice, graphics, handwriting, photographs, movies 3

3. Basic Networking Concepts Computer network  Set of independent computer systems connected by telecommunication links  Purpose: Sharing information and resources Nodes, hosts, or end systems  Individual computers on a network 4

4. Basic Networking Concepts Node: A Node is a connection point. In a physical Network, it is an electronic device that is attached to a network and is capable of sending, receiving and forwarding information over a communication channel (Network) Host: Any Computer connected to a network is considered a host.

5. Communication Links Switched, dial-up telephone line  A circuit is temporarily established between the caller and callee  Analog medium  Requires modem at both ends to transmit information produced by a computer Computer produces digital information 5

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7. Communication Links (continued) Dial-up phone links  Transmission rate: 56,000 bps (56 Kbps) Broadband  Transmission rate: Exceeding 256,000 bps (256 Kbps) 8

8. Communication Links (continued) Options for broadband communications  Home use Digital subscriber line (DSL) Cable modem Fiber Optics  Commercial and office environment Ethernet Fast Ethernet Gigabit Ethernet 9

9. Transmission Time of an Image at Different Transmission Speeds 10

10. Communication Links (continued) Wireless data communication  Uses radio, microwave, and infrared signals  Enables “mobile computing”  Types of wireless data communication Wireless local access network Wireless wide-area access network 11

11. Local Area Networks Local area network (LAN)  Connects hardware devices that are in close proximity  The owner of the devices is also the owner of the means of communications  Common wired LAN topologies Bus Ring Star 12

12. Figure 1.4 Some Common LAN Topologies 13

13. Local Area Networks (continued) Ethernet  Most widely used LAN technology  Uses the bus topology  Two ways to construct an Ethernet LAN Shared cable Hubs: The most widely used technology 14

14. An Ethernet LAN Implemented Using Shared Cables 15

15. Figure 7.6 An Ethernet LAN Implemented Using a Hub 16

16. Wide Area Networks Wide area networks (WANs)  Connect devices that are across town, across the country, or across the ocean  Users must purchase telecommunications services from an external provider  Dedicated point-to-point lines  Most use a store-and-forward, packet-switched technology to deliver messages 17

17. Typical Structure of a Wide Area Network 18

18. What is an IP Address:  An Internet Protocol address ( IP address ) is a numerical label assigned to each device (e.g., computer, printer) that is part of a Computer Network.  Example of IP address: 192.168.1.1  There are two types of IP addresses: Static and Dynamic.

19. Static vs Dynamic  Static IP: A fixed IP that is permanently assigned to a host.  Dynamic IP: A temporary IP that expires when the host goes offline, and changes the next time the host connects to the network.

20. How to know your IP address? Local IP Address: By running the CMD command in windows and typing: “ipconfig” in the terminal, then hitting enter. Public IP (given by the ISP): You can either visit a site such as http://whatismyipaddress.com/http://whatismyipaddress.com/ Or access your router to find out the actual IP address.