Week 12 (2012) Dr. Ghada Drahem

INTENDED LEARNING OUTCOMES This lecture covers: Networking concepts and terminology Common networking and communications applications Technical issues related to networks, including the major types of networks, how data is transmitted over a network, and types of transmission media involved Explanation of the various ways networked devices communicate with one another Various types of hardware used in conjunction with a computer network

3 WHAT IS A NETWORK? Network: A connected system of objects or people Computer network: A collection of computers and other hardware devices connected together so that users can share hardware, software, and data, as well as electronically communicate with each other Internet: Largest computer network in the world Types of networks Business networks Phone networks Home and multimedia networks

4 NETWORKING AND COMMUNICATIONS APPLICATIONS Mobile phones (wireless phones) Cellular (cell) phones Must be within range of cell tower to function Satellite phones Used where cell service isn’t available Dual-mode phones Allows users to make telephone calls on more than one network Cellular / Wi-Fi dual mode phone are most popular

5 NETWORKING AND COMMUNICATIONS APPLICATIONS Paging Sending short numeric or text messages to a person’s pager Most often used for onsite paging applications Messaging Two-way paging Most often takes place today via a mobile phone

6 NETWORKING AND COMMUNICATIONS APPLICATIONS Global positioning system (GPS): Uses satellites and a receiver to determine the exact geographic location of the receiver Commonly found in cars today Available as handheld units Used by the military, hikers, travelers, and others who need to know their precise location

7 NETWORKING AND COMMUNICATIONS APPLICATIONS Videoconferencing: Use of communications technology for real-time, face-to-face meetings between individuals located in different places

8 TYPES OF NETWORKS Topology: How the devices in the network (called nodes) are arranged Star networks: All devices connect to a central device or hub) Bus networks: All devices connect to a central cable Ring networks: Devices connect to one another in a ring Mesh networks: Multiple connections between devices Some networks use a combination of topologies

9 NETWORK TOPOLOGIES

10 TYPES OF NETWORKS Client-server networks Client: PC or other device on the network that requests and utilizes network resources Server: Computer dedicated to processing client requests

11 TYPES OF NETWORKS Peer-to-peer networks: All computers at the same level Internet peer-to-peer (P2P) computing: Performed via the Internet

12 TYPES OF NETWORKS Local area network (LAN): Small geographical area (office, campus, etc.) Wide area network (WAN): Large geographical area (Internet) Metropolitan area network (MAN): Serves a metropolitan area Personal area network (PAN): Connects personal devices for one individual, such as his or her portable PC, mobile phone, and portable printer

13 TYPES OF NETWORKS Wireless sensor networks (WSNs): Contain sensors (devices that respond to a stimulus and generate an electrical signal that can be measured or interpreted) Intranet: Private network set up by an organization for use by its employees Extranet: Intranet that is at least partially accessible to authorized outsiders Virtual private network (VPN): Secure path over the Internet that provide authorized users a secure means of accessing a private network via the Internet

14 DATA TRANSMISSION CHARACTERISTICS Analog vs. digital (waves vs. discrete) Bandwidth: The amount of data that can be sent at during a given period of time Measured in bits per second (bps) Serial vs. parallel transmission Serial = 1 bit Parallel = at least 1 byte at a time

15 DATA TRANSMISSION CHARACTERISTICS Transmission timing Synchronous transmission (at regular, specified intervals) Asynchronous transmission (sent when ready) Isochronous transmission (sent at the same time as other, related, data)

16 DATA TRANSMISSION CHARACTERISTICS Transmission directions Simplex transmission (one way only) Half-duplex transmission (one way at a time) Full-duplex transmission (both ways at the same time)

17 DATA TRANSMISSION CHARACTERISTICS Type of connections Circuit-switched: Dedicated path over a network is established and all data follows that path Packet-switched: Messages are separated into small units called packets and travel along the network separately Used to send data over the Internet Broadcast: Data is sent out to all other nodes on the network Primarily used with LANs

18 TYPE OF CONNECTIONS

19 DATA TRANSMISSION CHARACTERISTICS Wired connections: The PC is physically cabled to the network Common in schools, business, and government facilities Wireless connections: Typically use radio waves to send data through the air Rapidly becoming more popular in homes and businesses Wireless hotspots are commonly available in public locations

20 WIRED NETWORK TRANSMISSION MEDIA

21 WIRELESS NETWORK TRANSMISSION MEDIA

22 CELLULAR RADIO TRANSMISSIONS

23 MICROWAVE AND SATELLITE TRANSMISSIONS

24 NETWORKING STANDARDS AND COMMUNICATIONS PROTOCOLS Standards: A set of criteria or requirements considered to be the approved model for something Networking standards: Address how networked computers communicate and connect Communications protocol: An agreed-upon standard for transmitting data between two devices on a network In networking, standards and protocols specify how: Devices physically connect to a network Data is packaged for transmission Receiving devices acknowledge signals Errors are handled

25 ETHERNET communications protocol Ethernet: Most widely used communications protocol for wired LANs Typically used a bus or star topology and twisted-pair, coaxial, or fiber-optic cables Power over Ethernet: Allows electrical power to be sent along with data on an Ethernet network Most often used by businesses

26 TCP/IP AND WIRELESS APPLICATION PROTOCOL (WAP) TCP/IP (Transmission Control Protocol/Internet Protocol): Used for transferring data over the Internet Wireless Application Protocol (WAP): A standard for delivering Internet content to mobile devices